The Major Histocompatibility Complex (MHC) was discovered in the 1940s through transplantation experiments in mice. MHC molecules are highly polymorphic cell surface proteins that present antigens to T cells and determine whether grafts are accepted or rejected. MHC was further characterized through serologic studies in humans showing that transplantation rejection correlated with antibodies targeting HLA antigens on donor cells.
The document discusses the major histocompatibility complex (MHC), including its discovery through transplantation experiments in mice, serologic studies in humans, and the structure and function of MHC molecules. MHC molecules present antigen fragments to T cells and play a key role in the immune system by distinguishing self from non-self. There are two major classes of MHC molecules: Class I presents intracellular peptides to cytotoxic T cells, while Class II presents extracellular peptides to helper T cells.
Transplantation involves transferring cells or tissues between individuals and can be lifesaving but also carries immunological risks. Major histocompatibility complex (MHC) proteins encoded by HLA genes are the main targets recognized by the recipient's immune system, leading to graft rejection. Careful HLA typing and screening for antibodies is crucial before transplantation to minimize immunological incompatibility between donor and recipient. Immunosuppressive drugs are used to reduce the immune response and prevent rejection after transplantation.
The document discusses HLA typing and its implications. It begins with a brief history of the discovery of the major histocompatibility complex (MHC) in mice and humans. It then describes the structure and functions of the MHC, including the class I, class II, and class III regions. The document discusses methods of HLA typing, including serological testing using microcytotoxicity and molecular methods. It notes some implications of HLA typing, such as its role in organ transplant matching and susceptibility to autoimmune disease.
The document provides an overview of major histocompatibility complex (MHC) and human leukocyte antigen (HLA) typing. It discusses that MHC molecules present antigen fragments to T cells and are classified into classes I, II, and III. MHC proteins in humans are called HLA genes and are located on chromosome 6. The document describes HLA classification, functions in infectious disease, graft rejection, and autoimmunity, as well as genetics and methods of HLA typing including serotyping, phenotyping, and allele names.
The document summarizes the key organs of the immune system. It describes the thymus and bone marrow as the primary lymphoid organs where lymphocyte maturation occurs. The lymph nodes, spleen, gut-associated lymphoid tissue, and skin-associated lymphoid tissues are described as the secondary lymphoid organs that trap antigens and allow immune cell interaction. The document also provides examples of how disruption or aging of the primary lymphoid organs like the thymus can impair immune function.
it is related to immunology .. Major histo compatibility complex - a highly polymorphic region on chromosome 6 with genes particularly involved in immune functions..
HLA forms part of the Major Histocompatibility Complex located on chromosome 6. It comprises two classes - Class I antigens (HLA-A, B, C) expressed on all nucleated cells and present antigens to cytotoxic T cells, while Class II antigens (HLA-DR, DQ, DP) are expressed on antigen presenting cells and present antigens to helper T cells. Molecular typing techniques like PCR and sequence-based typing provide high resolution results for HLA typing without requiring viable cells.
The document discusses the major histocompatibility complex (MHC), including its discovery through transplantation experiments in mice, serologic studies in humans, and the structure and function of MHC molecules. MHC molecules present antigen fragments to T cells and play a key role in the immune system by distinguishing self from non-self. There are two major classes of MHC molecules: Class I presents intracellular peptides to cytotoxic T cells, while Class II presents extracellular peptides to helper T cells.
Transplantation involves transferring cells or tissues between individuals and can be lifesaving but also carries immunological risks. Major histocompatibility complex (MHC) proteins encoded by HLA genes are the main targets recognized by the recipient's immune system, leading to graft rejection. Careful HLA typing and screening for antibodies is crucial before transplantation to minimize immunological incompatibility between donor and recipient. Immunosuppressive drugs are used to reduce the immune response and prevent rejection after transplantation.
The document discusses HLA typing and its implications. It begins with a brief history of the discovery of the major histocompatibility complex (MHC) in mice and humans. It then describes the structure and functions of the MHC, including the class I, class II, and class III regions. The document discusses methods of HLA typing, including serological testing using microcytotoxicity and molecular methods. It notes some implications of HLA typing, such as its role in organ transplant matching and susceptibility to autoimmune disease.
The document provides an overview of major histocompatibility complex (MHC) and human leukocyte antigen (HLA) typing. It discusses that MHC molecules present antigen fragments to T cells and are classified into classes I, II, and III. MHC proteins in humans are called HLA genes and are located on chromosome 6. The document describes HLA classification, functions in infectious disease, graft rejection, and autoimmunity, as well as genetics and methods of HLA typing including serotyping, phenotyping, and allele names.
The document summarizes the key organs of the immune system. It describes the thymus and bone marrow as the primary lymphoid organs where lymphocyte maturation occurs. The lymph nodes, spleen, gut-associated lymphoid tissue, and skin-associated lymphoid tissues are described as the secondary lymphoid organs that trap antigens and allow immune cell interaction. The document also provides examples of how disruption or aging of the primary lymphoid organs like the thymus can impair immune function.
it is related to immunology .. Major histo compatibility complex - a highly polymorphic region on chromosome 6 with genes particularly involved in immune functions..
HLA forms part of the Major Histocompatibility Complex located on chromosome 6. It comprises two classes - Class I antigens (HLA-A, B, C) expressed on all nucleated cells and present antigens to cytotoxic T cells, while Class II antigens (HLA-DR, DQ, DP) are expressed on antigen presenting cells and present antigens to helper T cells. Molecular typing techniques like PCR and sequence-based typing provide high resolution results for HLA typing without requiring viable cells.
The document summarizes key concepts of immunity, including:
1. Innate immunity provides immediate defenses through physical barriers and cells like phagocytes, while adaptive immunity provides specific responses through antibodies and T cells.
2. The immune system is composed of circulating leukocytes and lymphoid organs that bring together antigens and immune cells.
3. Adaptive immunity involves antigen presentation, lymphocyte activation, proliferation into effector and memory cells, and specialized functions of B cells, cytotoxic T cells, and helper T cells.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Immunoglobulins, also known as antibodies, are glycoproteins produced by plasma cells that recognize and bind to specific antigens. There are five main classes of immunoglobulins - IgG, IgA, IgM, IgD, and IgE - which differ in their structure and function. IgG is the most abundant antibody found in serum and body tissues, while IgA is predominantly found in secretions such as breast milk, tears, and saliva where it provides immune protection of mucosal surfaces. IgM is the first antibody to respond to new antigens and plays a key role in activating the complement system.
Immunity against Helminths:role of InterleukinsIshfaq Maqbool
The document summarizes key aspects of the immune response against helminth parasites. It notes that helminths typically induce a type 2 immune response characterized by cytokines like IL-4, IL-5, and IL-13. This non-inflammatory response involves alternatively activated macrophages, eosinophils, and other effector cells that work to expel and kill parasites while repairing tissue damage. The response differs from bacterial and viral immunity, with Th1 responses only occurring during early larval migration stages.
The innate immune response is the first line of defense against infection and predates the adaptive immune response. It uses germline-encoded pattern recognition receptors (PRRs) to recognize pathogen-associated molecular patterns (PAMPs) and initiate a proinflammatory response. The major PRR families are Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), NOD-like receptors (NLRs), and C-type lectin receptors (CLRs). TLRs recognize bacteria and viruses at the cell surface and within endosomes, and signal through either the MyD88 or TRIF adaptor pathways to induce inflammatory cytokines and type I interferons. NLRs and RLRs function
The immune system recognizes foreign organisms through pattern recognition receptors (PRRs) that detect pathogen-associated molecular patterns (PAMPs) shared by pathogens. The innate immune system responds first through phagocytic cells like granulocytes and antigen-presenting cells that engulf and kill pathogens. It also activates the adaptive immune system. Adaptive immunity recognizes pathogens through highly specific B and T cell receptors generated through genetic recombination, ensuring recognition of virtually any pathogen. Activated T cells then stimulate B cells and other T cells to eliminate the pathogen through targeted antibody production and cell-mediated responses.
The major histocompatibility complex (MHC) refers to a group of genes that code for cell surface molecules that present peptide fragments to T cells and help the immune system distinguish self from non-self. MHC molecules play a key role in transplant rejection and disease susceptibility. There are two major classes of MHC molecules - Class I molecules present intracellular peptides to CD8 T cells while Class II molecules present extracellular peptides to CD4 T cells. Cytokines are chemical messengers that mediate communication between immune cells and are involved in processes like inflammation, hematopoiesis, and antiviral responses. Dysregulation of cytokines can lead to conditions like septic shock and cytokine storm.
This document summarizes a biology lecture on antigen processing and presentation. It discusses two key points:
1) T cells can only recognize antigens when presented by self-MHC molecules on antigen presenting cells. Experiments in the 1970s and 1980s demonstrated that T cells only respond to antigens presented by APCs that share the same MHC alleles.
2) There are two pathways for antigen processing and presentation. The endogenous pathway involves degradation of intracellular proteins by the proteasome and presentation of peptides on MHC class I molecules. The exogenous pathway involves uptake and degradation of extracellular proteins in endosomes and presentation of peptides on MHC class II molecules.
The major histocompatibility complex (MHC) plays a key role in the immune system by presenting antigens and distinguishing self from non-self. It is located on chromosome 6 in humans and contains genes like HLA that determine disease susceptibility. MHC molecules come in two classes: class I present intracellular peptides and class II present extracellular peptides. Variants in MHC genes can increase risk for certain diseases, like a variant in HLA-DQ increasing susceptibility to type 1 diabetes. Loss of MHC diversity in some populations like cheetahs can also lead to increased disease emergence due to a less broad range of antigens recognized.
The document summarizes key aspects of innate immunity and the complement system. It describes how the complement system recognizes microbes via three pathways: the classical, lectin, and alternative pathways. It also outlines the three main functions of complement in host defense: opsonization, chemotaxis, and formation of the membrane attack complex. The summary concludes by mentioning how deficiencies in complement proteins can increase susceptibility to certain infections.
The document discusses various aspects of immunology and immunodiagnostics. It contains 20 multiple choice questions that test understanding of topics like innate and adaptive immunity, the cells and molecules involved in each, tolerance, and the differences between humoral and cell-mediated immunity. Key cells mentioned include B cells, T cells, macrophages, neutrophils, and natural killer cells. Cytokines like interferons and interleukins are discussed in the context of their roles in immune responses.
This document provides information on MHC class I and class II molecules, including their structure, function, and role in antigen presentation. It discusses that MHC class I molecules are expressed on all nucleated cells and present intracellular antigens to CD8+ T cells. MHC class II molecules are expressed primarily on antigen presenting cells and present extracellular antigens to CD4+ T cells. The peptide binding grooves of MHC class I and II molecules differ in their structure and the size of peptides they can bind.
The document summarizes the structure and immune functions of normal skin. It describes the three layers of skin - epidermis, dermis and subcutis. It details the cells involved in innate and adaptive immunity in skin, including keratinocytes, Langerhans cells, dermal dendritic cells, T cells and cytokines. It explains how the skin provides a physical barrier and contains cells and molecules that protect against pathogens as part of the innate immune system.
This document provides an overview of the innate immune system, including its components and functions. It discusses:
1) The major components of innate immunity include anatomical barriers, cellular responses like phagocytosis, and soluble proteins. Innate immunity provides the initial response to pathogens and stimulates adaptive immunity.
2) Innate immune cells recognize pathogens through pattern recognition receptors (PRRs) that bind pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Major PRR families include Toll-like receptors, NOD-like receptors, RIG-I-like receptors, and C-type lectin receptors.
3) Defects in PRR signaling pathways can increase
The document summarizes key aspects of innate immunity in 3 paragraphs or less:
Innate immunity provides the first line of defense against pathogens and includes physical barriers and fixed mechanisms that are always ready. It responds immediately through mechanisms like antimicrobial peptides, complement proteins that tag pathogens, and pattern recognition receptors on macrophages that help clear infections. Phagocytes like macrophages and neutrophils work to eliminate invading pathogens through receptors, phagocytosis, and secretion of inflammatory cytokines and chemokines to recruit more immune cells. Together the fixed and cellular defenses of innate immunity function to quickly control infections before the adaptive immune response is deployed.
The document summarizes key aspects of the immune system. It discusses the central and peripheral organs of the immune system including the thymus, bone marrow, spleen, lymph nodes, and tonsils. It describes the development and maturation of white blood cells and B and T lymphocytes. It also summarizes the differences between humoral and cell-mediated immunity and the roles of B cells, T cells, antibodies, and cytokines in the immune response.
The document discusses the Major Histocompatibility Complex (MHC) and its role in organ transplantation and immune response. It covers MHC genetics and polymorphism, allorecognition of T cells, mechanisms of graft rejection, immunosuppressive agents used to prevent rejection, and the use of tissue typing to match donors and recipients to improve graft survival.
The seminar presented discussed the major histocompatibility complex (MHC). MHC molecules are surface proteins located on nucleated cells that play an important role in identifying antigens and presenting them to T cells to trigger an immune response. The seminar covered the definition of MHC, its history of discovery, the different classes of MHC molecules including their structure and function, examples in humans (HLA) and mice (H-2 complex), and concluded with a summary of how MHC molecules recognize both endogenous and exogenous antigens to initiate an immune response. The seminar was presented by Miss. Sandhya Sahu and guided by her professor Mr. Shishir Vind Sharma at Rungta College of Science & Technology,
Biology 151 is a 3-unit course on immunology taught in the second semester of 2010-2011. Student grades are based 70% on two lecture exams and quizzes and journal reports. Students can be exempted from the final exam if they have a pre-final average of 75% or higher and passing grades in both the lecture and laboratory components. Students who miss an exam for a valid reason will take the final exam, which will substitute for the missed exam score. The course covers topics such as the immune system cells and organs, antigens, antibodies, immunoglobulin genes, antigen processing and presentation, T-cells and B-cells, cytokines, the complement system, cell-mediated effector response, and immunity
This document discusses key concepts in ecology and ecosystems. It begins by explaining that Earth is the only planet that supports life due to factors like its atmosphere, water, and perfect size. It then defines ecology as the study of interactions between organisms and between organisms and their environment. The document goes on to explain important ecological concepts like biotic and abiotic ecosystem components, producers and consumers, and feedback mechanisms. It also discusses how various abiotic factors like light, temperature, and soil properties influence biological systems.
This document provides an overview of topics that will be covered in Examination 2 for NS 2 COVERAGE. The topics include circulation and respiration, digestion, reproduction and aging, genetics and inheritance, and evolution and advances in biological sciences.
Under circulation and respiration, key concepts about open and closed circulatory systems, varying heart chambers, the functions of the heart, path of blood flow, pacemaker cells, the heartbeat, fetal circulation, blood vessels, control of blood pressure and flow, strokes vs heart attacks, blood composition, blood production and recycling, and blood doping are outlined.
Genetics and inheritance topics include blood typing and the Rh factor. Evolution and advances in biology section covers modified class schedule information and a
The document summarizes key concepts of immunity, including:
1. Innate immunity provides immediate defenses through physical barriers and cells like phagocytes, while adaptive immunity provides specific responses through antibodies and T cells.
2. The immune system is composed of circulating leukocytes and lymphoid organs that bring together antigens and immune cells.
3. Adaptive immunity involves antigen presentation, lymphocyte activation, proliferation into effector and memory cells, and specialized functions of B cells, cytotoxic T cells, and helper T cells.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Immunoglobulins, also known as antibodies, are glycoproteins produced by plasma cells that recognize and bind to specific antigens. There are five main classes of immunoglobulins - IgG, IgA, IgM, IgD, and IgE - which differ in their structure and function. IgG is the most abundant antibody found in serum and body tissues, while IgA is predominantly found in secretions such as breast milk, tears, and saliva where it provides immune protection of mucosal surfaces. IgM is the first antibody to respond to new antigens and plays a key role in activating the complement system.
Immunity against Helminths:role of InterleukinsIshfaq Maqbool
The document summarizes key aspects of the immune response against helminth parasites. It notes that helminths typically induce a type 2 immune response characterized by cytokines like IL-4, IL-5, and IL-13. This non-inflammatory response involves alternatively activated macrophages, eosinophils, and other effector cells that work to expel and kill parasites while repairing tissue damage. The response differs from bacterial and viral immunity, with Th1 responses only occurring during early larval migration stages.
The innate immune response is the first line of defense against infection and predates the adaptive immune response. It uses germline-encoded pattern recognition receptors (PRRs) to recognize pathogen-associated molecular patterns (PAMPs) and initiate a proinflammatory response. The major PRR families are Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), NOD-like receptors (NLRs), and C-type lectin receptors (CLRs). TLRs recognize bacteria and viruses at the cell surface and within endosomes, and signal through either the MyD88 or TRIF adaptor pathways to induce inflammatory cytokines and type I interferons. NLRs and RLRs function
The immune system recognizes foreign organisms through pattern recognition receptors (PRRs) that detect pathogen-associated molecular patterns (PAMPs) shared by pathogens. The innate immune system responds first through phagocytic cells like granulocytes and antigen-presenting cells that engulf and kill pathogens. It also activates the adaptive immune system. Adaptive immunity recognizes pathogens through highly specific B and T cell receptors generated through genetic recombination, ensuring recognition of virtually any pathogen. Activated T cells then stimulate B cells and other T cells to eliminate the pathogen through targeted antibody production and cell-mediated responses.
The major histocompatibility complex (MHC) refers to a group of genes that code for cell surface molecules that present peptide fragments to T cells and help the immune system distinguish self from non-self. MHC molecules play a key role in transplant rejection and disease susceptibility. There are two major classes of MHC molecules - Class I molecules present intracellular peptides to CD8 T cells while Class II molecules present extracellular peptides to CD4 T cells. Cytokines are chemical messengers that mediate communication between immune cells and are involved in processes like inflammation, hematopoiesis, and antiviral responses. Dysregulation of cytokines can lead to conditions like septic shock and cytokine storm.
This document summarizes a biology lecture on antigen processing and presentation. It discusses two key points:
1) T cells can only recognize antigens when presented by self-MHC molecules on antigen presenting cells. Experiments in the 1970s and 1980s demonstrated that T cells only respond to antigens presented by APCs that share the same MHC alleles.
2) There are two pathways for antigen processing and presentation. The endogenous pathway involves degradation of intracellular proteins by the proteasome and presentation of peptides on MHC class I molecules. The exogenous pathway involves uptake and degradation of extracellular proteins in endosomes and presentation of peptides on MHC class II molecules.
The major histocompatibility complex (MHC) plays a key role in the immune system by presenting antigens and distinguishing self from non-self. It is located on chromosome 6 in humans and contains genes like HLA that determine disease susceptibility. MHC molecules come in two classes: class I present intracellular peptides and class II present extracellular peptides. Variants in MHC genes can increase risk for certain diseases, like a variant in HLA-DQ increasing susceptibility to type 1 diabetes. Loss of MHC diversity in some populations like cheetahs can also lead to increased disease emergence due to a less broad range of antigens recognized.
The document summarizes key aspects of innate immunity and the complement system. It describes how the complement system recognizes microbes via three pathways: the classical, lectin, and alternative pathways. It also outlines the three main functions of complement in host defense: opsonization, chemotaxis, and formation of the membrane attack complex. The summary concludes by mentioning how deficiencies in complement proteins can increase susceptibility to certain infections.
The document discusses various aspects of immunology and immunodiagnostics. It contains 20 multiple choice questions that test understanding of topics like innate and adaptive immunity, the cells and molecules involved in each, tolerance, and the differences between humoral and cell-mediated immunity. Key cells mentioned include B cells, T cells, macrophages, neutrophils, and natural killer cells. Cytokines like interferons and interleukins are discussed in the context of their roles in immune responses.
This document provides information on MHC class I and class II molecules, including their structure, function, and role in antigen presentation. It discusses that MHC class I molecules are expressed on all nucleated cells and present intracellular antigens to CD8+ T cells. MHC class II molecules are expressed primarily on antigen presenting cells and present extracellular antigens to CD4+ T cells. The peptide binding grooves of MHC class I and II molecules differ in their structure and the size of peptides they can bind.
The document summarizes the structure and immune functions of normal skin. It describes the three layers of skin - epidermis, dermis and subcutis. It details the cells involved in innate and adaptive immunity in skin, including keratinocytes, Langerhans cells, dermal dendritic cells, T cells and cytokines. It explains how the skin provides a physical barrier and contains cells and molecules that protect against pathogens as part of the innate immune system.
This document provides an overview of the innate immune system, including its components and functions. It discusses:
1) The major components of innate immunity include anatomical barriers, cellular responses like phagocytosis, and soluble proteins. Innate immunity provides the initial response to pathogens and stimulates adaptive immunity.
2) Innate immune cells recognize pathogens through pattern recognition receptors (PRRs) that bind pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Major PRR families include Toll-like receptors, NOD-like receptors, RIG-I-like receptors, and C-type lectin receptors.
3) Defects in PRR signaling pathways can increase
The document summarizes key aspects of innate immunity in 3 paragraphs or less:
Innate immunity provides the first line of defense against pathogens and includes physical barriers and fixed mechanisms that are always ready. It responds immediately through mechanisms like antimicrobial peptides, complement proteins that tag pathogens, and pattern recognition receptors on macrophages that help clear infections. Phagocytes like macrophages and neutrophils work to eliminate invading pathogens through receptors, phagocytosis, and secretion of inflammatory cytokines and chemokines to recruit more immune cells. Together the fixed and cellular defenses of innate immunity function to quickly control infections before the adaptive immune response is deployed.
The document summarizes key aspects of the immune system. It discusses the central and peripheral organs of the immune system including the thymus, bone marrow, spleen, lymph nodes, and tonsils. It describes the development and maturation of white blood cells and B and T lymphocytes. It also summarizes the differences between humoral and cell-mediated immunity and the roles of B cells, T cells, antibodies, and cytokines in the immune response.
The document discusses the Major Histocompatibility Complex (MHC) and its role in organ transplantation and immune response. It covers MHC genetics and polymorphism, allorecognition of T cells, mechanisms of graft rejection, immunosuppressive agents used to prevent rejection, and the use of tissue typing to match donors and recipients to improve graft survival.
The seminar presented discussed the major histocompatibility complex (MHC). MHC molecules are surface proteins located on nucleated cells that play an important role in identifying antigens and presenting them to T cells to trigger an immune response. The seminar covered the definition of MHC, its history of discovery, the different classes of MHC molecules including their structure and function, examples in humans (HLA) and mice (H-2 complex), and concluded with a summary of how MHC molecules recognize both endogenous and exogenous antigens to initiate an immune response. The seminar was presented by Miss. Sandhya Sahu and guided by her professor Mr. Shishir Vind Sharma at Rungta College of Science & Technology,
Biology 151 is a 3-unit course on immunology taught in the second semester of 2010-2011. Student grades are based 70% on two lecture exams and quizzes and journal reports. Students can be exempted from the final exam if they have a pre-final average of 75% or higher and passing grades in both the lecture and laboratory components. Students who miss an exam for a valid reason will take the final exam, which will substitute for the missed exam score. The course covers topics such as the immune system cells and organs, antigens, antibodies, immunoglobulin genes, antigen processing and presentation, T-cells and B-cells, cytokines, the complement system, cell-mediated effector response, and immunity
This document discusses key concepts in ecology and ecosystems. It begins by explaining that Earth is the only planet that supports life due to factors like its atmosphere, water, and perfect size. It then defines ecology as the study of interactions between organisms and between organisms and their environment. The document goes on to explain important ecological concepts like biotic and abiotic ecosystem components, producers and consumers, and feedback mechanisms. It also discusses how various abiotic factors like light, temperature, and soil properties influence biological systems.
This document provides an overview of topics that will be covered in Examination 2 for NS 2 COVERAGE. The topics include circulation and respiration, digestion, reproduction and aging, genetics and inheritance, and evolution and advances in biological sciences.
Under circulation and respiration, key concepts about open and closed circulatory systems, varying heart chambers, the functions of the heart, path of blood flow, pacemaker cells, the heartbeat, fetal circulation, blood vessels, control of blood pressure and flow, strokes vs heart attacks, blood composition, blood production and recycling, and blood doping are outlined.
Genetics and inheritance topics include blood typing and the Rh factor. Evolution and advances in biology section covers modified class schedule information and a
This document outlines the syllabus for a Biology 151 immunology course. It includes the course description, objectives, calendar of activities, requirements and policies. The course covers the structure and function of the immune system, antigens and antibodies, innate and adaptive immunity, immunodeficiencies, and vaccines. It is comprised of lectures, laboratory sessions, exams and a group presentation on vaccine challenges. The grading is based on exam scores, quizzes, reports and performance.
The document discusses different types of vaccines, including active and passive immunization. It covers topics like whole-organism vaccines, purified macromolecules, recombinant-vector vaccines, DNA vaccines, and multivalent subunit vaccines. The document also addresses global vaccination challenges and provides information on recommended childhood immunization in the US.
This document provides an overview and introduction to immunobiology. It discusses that the immune system is composed of both the innate (non-specific) system and the adaptive (specific) system. The innate system provides a first line of defense through barrier tissues and cells that rapidly respond to invaders. The adaptive system provides a second line of defense through production of antibodies and cell-mediated responses that may take days to respond to a new infection. Both systems have cellular and humoral components that work together to protect the body, with signals between the two systems.
This document summarizes key aspects of adaptive immunity. It discusses how B and T lymphocytes recognize antigens through membrane-bound antibodies or T cell receptors, respectively. It describes the roles of antigen-presenting cells in capturing antigens and displaying them via MHC molecules to activate T lymphocytes. Major histocompatibility complex proteins display peptide fragments on antigen-presenting cells to trigger adaptive immune responses through T cell recognition.
This document provides an overview of controlling microbial growth through various physical and chemical methods. It defines key terms like sterilization, disinfection, sanitization, and antisepsis. Physical methods discussed include heat, radiation, filtration, and desiccation. Chemical methods include sterilants, disinfectants, sanitizers, antiseptics, and preservatives. The document also discusses factors that influence the effectiveness of antimicrobial agents and how their modes of action include damaging membranes, proteins, and nucleic acids. Assessment methods for disinfectants and chemotherapeutic agents like the phenol coefficient test, agar diffusion method, and minimum inhibitory concentration are also summarized.
This document provides an overview of Gregor Mendel's experiments with pea plants and the principles of heredity and genetics that he discovered. It discusses Mendel's work crossing pea plants with different traits, such as flower color, and recording the results in subsequent generations. His experiments showed that traits are inherited in discrete units (now known as genes) and follow predictable patterns, such as the 3:1 ratio he observed for dominant and recessive traits in the F2 generation of a monohybrid cross. The document also covers Mendel's principle of independent assortment observed in dihybrid crosses.
Cell-mediated immunity involves T lymphocytes that combat intracellular microbes. There are two phases: activation of naive T cells by antigen-presenting cells in lymphoid tissues, followed by migration of effector T cells to sites of infection. Effector T cells differentiate into subsets like TH1 and TH2 cells that secrete cytokines activating other immune cells. CD8+ T cells become cytotoxic T lymphocytes that directly kill infected cells. Memory T cells remain after infection clearance to provide rapid protection upon reexposure.
The document summarizes a lecture on viral structure and classification. It outlines the structure of viruses including the core, which contains the viral DNA or RNA genome, capsids made of protein subunits, and some viruses also have an outer envelope. It also discusses different viral morphologies like helical and icosahedral shapes. The lecture covers the relationship between viral structure and function.
The document discusses chemotherapeutic agents and antibiotics. It states that antibiotics are medicines used to treat bacterial infections, but not viral infections as antibiotics do not cure all infections. It notes that misuse of antibiotics can lead to no healing effect if used on viral infections, and can cause antibiotic resistance requiring stronger antibiotics. The document discusses various mechanisms of antibiotic resistance in bacteria and ways individuals may contribute to growing resistance through misuse of antibiotics.
This document summarizes cell-mediated effector response biology. It discusses how cell-mediated immunity detects and eliminates intracellular pathogens and tumor cells through cells like CD8+ cytotoxic T lymphocytes and cytokine-secreting CD4+ T cells. It describes the mechanisms by which cytotoxic T cells and natural killer cells kill infected or abnormal cells through directed release of cytotoxic proteins or interaction of membrane-bound ligands and receptors on target cells.
The document summarizes a biology lecture on hypersensitivities and immunity to infectious diseases. It discusses the four types of hypersensitivities - type I or immediate hypersensitivity, type II or cytotoxic hypersensitivity, type III or immune complex-mediated hypersensitivity, and type IV or delayed hypersensitivity. It also covers immunity against various infectious agents such as viruses, bacteria, fungi, parasites and emerging/re-emerging infections. The lecture focuses on innate and adaptive immune responses mounted by the host against infectious diseases.
The document discusses nutrient cycling and biogeochemical cycles. It explains that nutrients are transported through organisms, atmosphere, water, and land in a series of cycles. The main cycles discussed are the water, oxygen, carbon, nitrogen, phosphorus, and sulfur cycles. It describes the reservoirs, chemical forms, and processes involved in each cycle. It also addresses how human activities like pollution, use of fertilizers, and deforestation can disrupt nutrient cycling and cause issues like eutrophication, ozone depletion, and acid rain. Potential solutions to remediate disrupted cycles, like bioremediation using bacteria, fungi, plants and algae, are also mentioned.
This document provides an overview of biodiversity in the Philippines. It begins by defining key terms like endemism. It then discusses the high plant diversity in the Philippines, noting there are an estimated 12,000 plant species, with many ferns, orchids, and mosses being endemic. The document highlights some examples of endemic species within these groups. It also addresses the country's status as one of 17 megadiverse countries and notes the large numbers of endemic animal species like birds, mammals, and reptiles found in the Philippines. Threats to the country's biodiversity like habitat loss are also examined.
This document discusses immunity to various infectious diseases. It covers innate and adaptive immunity, immunity to viruses, bacteria, fungi, protozoa and helminths. For bacteria, both extracellular and intracellular types are discussed. The roles of antibodies and cell-mediated responses are described for different pathogens depending on where they reside in the host. Mechanisms by which pathogens evade immunity are also summarized.
This document outlines a biology lecture on the diversity of microorganisms. It discusses the classification of microbes into three domains: Archaea, Bacteria, and Eukarya. Within these domains, different types of prokaryotes and eukaryotes are described, including bacteria, archaea, fungi, algae, protozoa, helminths, and viruses. Various identification techniques for microbes are also mentioned.
Lecture on DNA to Proteins (The Central Dogma of Molecular Biology)Marilen Parungao
- Transcription must occur before translation. Transcription involves copying DNA into mRNA, which is then used as a template for translation.
- The LAC operon is activated under conditions where glucose is low/lactose is high. It is inactivated when glucose is high/lactose is low.
- The DNA sequence provided would be transcribed into an RNA sequence where all Ts would be replaced with Us: 3'-UAC GGC AUU GCA CAU UUU AGG GGC AAU AUU-5'
This document discusses autoimmunity and autoimmune diseases. It begins by defining autoimmunity as a breakdown of self-tolerance mechanisms that leads to an adaptive immune response against self-antigens. This can result in chronic inflammation and autoimmune disease. Several proposed mechanisms for how autoimmunity occurs are described, including defects in central and peripheral tolerance. Factors like genetics, hormones, infections, and environmental exposures are thought to contribute to loss of self-tolerance. The document then classifies and describes some examples of organ-specific and systemic autoimmune diseases in more detail.
General principles of immunology and MHC - converted.pdfsubhankar9366
1. The document discusses principles of immunology including recognition, effector response, memory response, antigens, immunogens, epitopes, and types of immunity.
2. It describes the major classes of antigens that can induce an immune response and examples of cross-reactivity between antigens.
3. The roles and expression of MHC class I and II molecules are summarized, including their involvement in antigen processing and presentation to T cells.
Transplantation involves transferring cells, tissues, or organs from a donor to a recipient. Major challenges include graft rejection by the recipient's immune system and limited availability of donor organs. The document discusses the history of transplantation, types of transplants including autografts and allografts, transplantation antigens such as MHC and ABO antigens, graft rejection mechanisms including direct and indirect allorecognition, stages of rejection, and approaches to prevent rejection such as immunosuppressive drugs.
1. The document discusses the major histocompatibility complex (MHC), a gene complex encoding cell surface molecules that present antigens and are responsible for graft rejection.
2. MHC molecules exist in two main classes, MHC class I and II. Class I presents antigens to CD8+ T cells and is found on all nucleated cells. Class II presents antigens to CD4+ T cells and is found on antigen presenting cells.
3. MHC molecules are highly polymorphic, with many alleles present within populations, ensuring a diverse ability to present a wide range of antigens and defend against pathogens.
This document discusses MHC haplotypes, immune responsiveness, and disease susceptibility. It begins by outlining topics including inheritance of MHC haplotypes in mice (H-2) and humans (HLA), the relationship between MHC and immune responsiveness, and the association between MHC and disease susceptibility. It then provides details on MHC polymorphism and haplotype inheritance, the role of MHC in determining immune responses, and examples of diseases linked to specific MHC alleles.
introduction, history, classification of grafts, transplantation antigens, role of MHC in transplantation, immunology of allogenic transplantation, types of graft rejection, immunology of xenogeneic transplatation, organ trannsplantation.
MHC genes evolve through duplication, followed by diversification, co‐evolution, and sequence exchange. The focus, for HLA in transplantation, has been the specific classical class I and class II human leukocyte antigen (HLA) molecules and alleles. Importantly, anti‐HLA antibodies developed after the organ transplants play a role in acute and chronic allograft rejection, highlighting the need to detect these antibodies in a clinically relevant manner. Although the immune response to HLA antigens plays a pivotal role in allograft rejection, evidence shows that non‐HLA antigens also contribute to the pathogenesis of acute and chronic rejection, which limits long‐term graft survival of the solid organ transplants.
Major histocompatibility complex and antigen presentation & processingAISHUJ3
The major histocompatibility complex (MHC) was discovered through studies of transplant rejection in inbred mouse strains. The MHC encodes three classes of molecules - class I molecules present peptides to CD8+ T cells, class II molecules present peptides to CD4+ T cells, and class III molecules play roles in immune responses. MHC molecules have a peptide-binding cleft that binds peptides derived from antigens. The polymorphisms in MHC genes allow presentation of a wide variety of peptides and help populations respond to diverse pathogens.
The major histocompatibility complex (MHC) is a cluster of genes found in all mammals that encodes proteins important for the immune system to distinguish self from non-self. MHC molecules are expressed on the cell surface and present peptide antigens to T cells. There are three main classes of MHC genes - class I presents endogenous peptides to cytotoxic T cells, class II presents exogenous peptides to helper T cells, and class III encodes non-antigen presenting proteins involved in immunity. MHC molecules have binding sites that allow them to bind a variety of peptide antigens through anchor residues, helping the immune system recognize a diverse array of pathogens. Polymorphism of MHC alleles within populations helps provide protection against rapidly mutating pathogens.
major histocompatibility cells and its role in immunity. one of the main mechanisms of innate and acquired immunity in human body defense mechanism. it includes both the major and minor forms and different types of cells that are involved in. difference between innate and acquired immunity and its role in autoimmune disorders. the concept of advanced immunology. modern concepts in immunology.
minor histocompatibility molecules. definition and functions of major histocompatibilty molecules. role in autoimmune disorders. immunology and micro-invironment. role of genetics in immunity. minor cells are lymphocytes and plasma cells. acute cells are neutrophils or PMNLS. ROLE OF INFLAMMATIO IN IMMUNITY. role of cell membrane receptors in immunity and immune-mediated diseases.
The major histocompatibility complex (MHC) is a cluster of genes located on chromosome 6 in humans that encodes proteins involved in the immune system's recognition of self and non-self. The MHC includes class I, II, and III genes. Class I genes produce molecules that present intracellular peptides to cytotoxic T cells, while class II genes produce molecules that present extracellular peptides to helper T cells. Antigens are processed through either the cytosolic or endocytic pathway and bound to MHC molecules to be presented at the cell surface for recognition by T cells.
The document discusses the major histocompatibility complex (MHC), which are surface proteins that play an important role in identifying antigens and presenting them to T cells. It covers the different classes of MHC molecules, their structures, functions in immunity, and examples in humans (HLA) and mice (H-2 complex). MHC molecules present peptide fragments on their surface and interact specifically with T cells through anchor residues on the peptides. They are essential for self/non-self discrimination, defense against infection, and transplantation compatibility.
IMMUNITY OF BODY IN VERY IMPORTANT IN THE DEFENSE OF THE BODY. THERE ARE TWO TYPES OF IMMUNITY ADAPTIVE IMMUNITY AND INNATE IMMUNITY. THE CURRENT UPLOAD DEALS WITH BRANCHES OF ADAPTIVE IMMUNITY.
Antigen processing and presentation involves antigen-presenting cells ingesting and partially digesting proteins into peptide fragments, then displaying those fragments on MHC class I or II molecules. There are two pathways: endogenous antigens from within cells bind to MHC I and are recognized by cytotoxic T cells, while exogenous antigens endocytosed by APCs bind to MHC II and are recognized by helper T cells. Professional APCs like dendritic cells, macrophages, and B cells specialize in efficient antigen presentation and activation of T cell responses.
The document provides an overview of the principles of the immune system. It discusses the components of the innate and acquired immune systems. The innate system provides nonspecific first line defenses while the acquired system develops specific responses through adaptive immunity. Key cells involved include B and T lymphocytes that develop in primary lymphoid organs like the bone marrow and thymus and respond to antigens in secondary lymphoid organs. The major histocompatibility complex plays an important role in antigen presentation and self/non-self discrimination. Humoral immunity involves antibody-mediated responses while cellular immunity involves T cell-mediated responses.
Human Leukocyte Antigen (HLA) typing involves determining the presence of HLA antigens on white blood cells. HLA antigens are encoded by genes in the major histocompatibility complex located on chromosome 6. HLA typing was originally done using serology to detect antibodies binding to HLA antigens, but now molecular techniques are more commonly used. HLA antigens are highly polymorphic and inherited as haplotypes from each parent, contributing to diversity in transplantation compatibility.
The major histocompatibility complex (MHC) is a set of surface proteins that present antigens to T cells. MHC molecules are classified into two groups: Class I MHC molecules are expressed on all nucleated cells and present intracellular antigens to CD8+ T cells. Class II MHC molecules are mainly expressed on antigen-presenting cells and present extracellular antigens to CD4+ T cells. MHC molecules play an important role in organ transplantation by determining tissue compatibility and in the immune response by ensuring the correct response is mounted against different pathogens.
Major Histocompatibility Complex (MHC) molecules display antigen peptides on the surface of cells to be recognized by T cells. There are two main types of MHC molecules: class I molecules present intracellular peptides to CD8+ T cells on most nucleated cells, while class II molecules present extracellular peptides to CD4+ T cells on antigen-presenting cells like dendritic cells and macrophages. MHC molecules bind peptides promiscuously but polymorphisms among individuals influence peptide binding. Dendritic cells are especially effective at antigen capture and presentation to initiate primary T cell responses.
Immune tolerance refers to a state where an immune response is expected but does not occur. It is induced by prior exposure to an antigen during development of the immune system. Central tolerance occurs in the thymus and bone marrow where T and B cells that strongly react to self-antigens undergo deletion or anergy. This process ensures the immune system does not attack the body's own tissues.
MAJOR HISTOCOMPATIBILITY COMPLEX AND HEAT SHOCK PROTEINSiva Ramakrishnan
The document discusses major histocompatibility complex (MHC) and heat shock proteins (HSP) in chickens. MHC genes encode proteins that present antigens and are involved in immune response and recognition. HSPs help proteins fold correctly and prevent aggregation. Both MHC and HSP play important roles in immune function, disease resistance, and stress response in chickens. Manipulation of these genes may help improve production traits and resistance to disease.
Traditional versus Modern Biotechnology (Exam 2 coverage)Marilen Parungao
Traditional (classical) biotechnology includes fermentation, breeding, and the production of antibiotics and vaccines. Fermentation involves using microbes like yeast and bacteria to produce foods and beverages through anaerobic respiration, including beer, wine, cheese, bread and yogurt. Breeding techniques like inbreeding and crossbreeding were used to selectively develop plant and animal varieties with desirable traits. Early methods discovered antibiotics produced by microorganisms and used vaccines containing weakened or killed pathogens to trigger immune responses without causing illness.
This document discusses biodiversity, including its definition, levels, importance, threats, and status in the Philippines. It defines biodiversity as the variety of life on Earth, including diversity at the genetic, species, and ecosystem levels. The lecture notes cover the three main levels of biodiversity and provides examples. It emphasizes that biodiversity is important to preserve for economic, aesthetic, and scientific reasons. Major threats to biodiversity include habitat loss, overexploitation, climate change, pollution, and invasive species. The document concludes that the Philippines is one of the most biodiverse countries in the world, with over half of its plant and animal species being endemic.
Traditional (classical) biotechnology refers to techniques that have been used for thousands of years, such as fermentation processes. Key applications of fermentation included producing foods like beer, wine, cheese, bread and yogurt. These processes harness microbes like yeast and bacteria to convert sugars into products like ethanol, lactic acid, carbon dioxide and other compounds, allowing foods to be preserved and enhancing flavors. Traditional biotechnology built upon ancient techniques and helped enable major advances in food production and medicine.
Transcription must occur before translation because a ribosome needs an mRNA blueprint to construct a protein. The operator is activated when lactose binds to the lac repressor and inactivated when the lac repressor binds to the operator. The last line shows a sequence of mRNA codons.
This document discusses nucleic acids and proteins, including their structures and functions. It provides information on DNA and RNA, such as their components, properties, and roles in coding for proteins. Key experiments that helped identify DNA as the genetic material are summarized, including Griffith's transformation experiment, Avery-MacLeod-McCarty experiment, and Hershey-Chase experiment. Questions are also included about nucleic acid and protein structures and these classic experiments.
The document contains a calendar of activities for Marilen M. Parungao-Balolong covering topics such as calendar of activities, energy concepts and energy flow, ecology, ecosystem concepts, and energy flow, with each topic containing multiple entries attributed to Marilen M. Parungao-Balolong.
The document contains the calendar of activities and lecture notes from a biology class taught by Marilen M. Parungao-Balolong. The lecture covers the fundamentals of chemistry of life, including atoms, chemical bonds, important biological molecules like carbohydrates, lipids, proteins and nucleic acids. It also discusses the domains of life including viruses, prokaryotes and eukaryotes. The functional anatomy of different cell types like plant, animal, bacterial and yeast cells are presented. The lecture concludes with topics on metabolism, catabolism, anabolism, cellular respiration and fermentation.
The document discusses different perceptions of and approaches to nature and the environment. It outlines major perceptions like everything being connected or nature having a delicate balance. It then discusses environmental ethics and different world views like biocentrism, ecocentrism, and anthropocentrism. Biocentrism and ecocentrism view humans as part of the environment, while anthropocentrism views nature as existing for human use. The document argues that anthropocentric views can lead to problems like overpopulation. It suggests adopting more ecocentric values to better care for the environment. Finally, it defines environmental justice as the fair treatment of all people regarding environmental laws and policies.
This document provides an introduction and overview of biotechnology, including definitions of key terms and an historical timeline of important developments in the field. It begins with definitions of biotechnology and genetic engineering. It then outlines the timeline of biotechnology from early domestication and farming in Mesopotamia through modern developments like recombinant vaccines, cloning, and the human genome project. The document concludes with a note about an upcoming meeting to level off on the material.
This document outlines the activities and requirements for a course on biotechnology. It includes lectures, presentations, exams, lab activities and field trips. There will be three exams covering introduction to techniques, applications of biotechnology, and international laws and guidelines. Students will work in groups to present on developing a GMO and create an exhibit for BioWeek. The course will also include virtual laboratory activities covering DNA extraction, PCR, gel electrophoresis, and microarrays. The last meeting will discuss isolating genes from plants and animals as well as human cloning and stem cell research.
The document outlines the content of a lecture on modern biotechnology. It discusses DNA as the genetic material and how genes are passed from parents to offspring in prokaryotic and eukaryotic systems. It also describes how modern biotechnology uses techniques like gene cloning and genetic engineering to develop genetically modified organisms (GMOs) by inserting foreign genes. Specific examples covered include the development of Golden Rice to address vitamin A deficiency and the use of GMOs in health, industry, food, and the environment.
The document discusses the history and development of vaccines from Edward Jenner's pioneering smallpox vaccine in the 18th century to modern vaccines. It covers key topics such as passive and active immunity, commonly used vaccine types including live attenuated, killed/inactivated, subunit/component, toxoid, and DNA vaccines. Safety considerations, efficacy, target groups, and monitoring of vaccine effects are also addressed.
Microbial growth refers to an increase in the number of microbial cells rather than an increase in cell size. Microbes require certain physical, chemical and nutritional conditions to grow, including a source of carbon, nitrogen, phosphorus and other trace elements. Temperature, pH, oxygen levels and osmotic pressure also influence microbial growth. Pure cultures can be obtained through streak plating and maintained through subculturing or freezing methods like glycerol stocks.
This document contains calendars of activities for Biology 196 for two sections, TBYZ and FBYZ, listing dates from August to October, with speakers, facilitators, and reactors assigned for each date. Students are scheduled to fulfill each role on different dates. The same activity of submitting a review paper to the teacher and reactor is listed for August 14 for both sections.
The document discusses whether microbe extinction should be cared about. It notes that while over 99% of species that have ever lived are extinct, microbes are ubiquitous and diverse. However, their roles in biogeochemical cycles and symbiotic relationships mean local extinctions could have large impacts. Evidence suggests microbes can face extinction through habitat loss, pollution, and climate change. Their potential losses through these human-caused threats to ecosystems should be a concern.
The document discusses the definition and requirements for microbial growth. Microbial growth is defined as an increase in the number of cells rather than cell size. The key requirements for microbial growth include physical factors like temperature, pH, and osmotic pressure as well as chemical nutrients like carbon, nitrogen, sulfur, phosphorus, trace elements, oxygen, and organic growth factors. Different microbes have different temperature, pH, and osmotic pressure preferences and obtain nutrients from various sources.
Humoral immunity is mediated by antibodies and functions to neutralize extracellular microbes and toxins. B-cells respond to and produce antibodies specific for many molecule types. When a B-cell encounters an antigen, it becomes activated and differentiates into a plasma cell that secretes antibodies of that specificity. T-cell help is required for effective antibody responses against protein antigens and drives affinity maturation and isotype switching.
This document contains calendars of activities for Biology 196 for two sections, TBYZ and FBYZ, listing dates from August to October, with speakers, facilitators, and reactors assigned for each date. Students are scheduled to fulfill each role on different dates. The same activity of submitting a review paper to the teacher and reactor is listed for August 14 for both sections.
This document summarizes innate immunity. It discusses how innate immunity provides a first line of defense through mechanisms that are always active and non-specific, such as physical barriers and cellular responses. Components of innate immunity include epithelial barriers, phagocytes, natural killer cells, the complement system, and inflammatory cytokines. These components work together to recognize microbes, initiate inflammation, opsonize pathogens, and eliminate infections before they can become established.
The document discusses microscopy techniques used to study microbial cell biology. It covers different types of microscopy like brightfield, darkfield, light microscopy, and electron microscopy. It also discusses sample preparation techniques for microscopy, including wet mounts, fixed smears, and different staining methods like Gram staining, acid-fast staining, and negative staining. The document provides examples of how these microscopy techniques can be used to visualize microbial cell structures and differentiate between bacterial cell types.
2. Discovery of the Major
Histocompatibility Complex
Transplantation experiments in Mice
Serologic Studies in Humans
Structure and Function of MHC
Molecules
Class I and Class II
Expression and Regulation of MHC
Molecules
Parungao-Balolong 2011
3. INTRO...
• MAJOR HISTOCOMPATIBILITY COMPLEX
(MHC)
• a region of highly polymorphic gene whose
products are expressed on the surfaces of a
variety of cells
• discovered in the 1940s via an artificial
transplantation experiments
• principal determinants of graft rejection
• THUS: individuals who express the same MHC
molecules accept tissue grafts from one another,
and, individuals who differ at their MHC loci
vigorously rejects such grafts
Parungao-Balolong 2011
4. INTRO...
MHC: ROLE IN IMMUNE RESPONSE???
1960s: Benacerraf et al
demonstrated that different inbred strains of guinea pigs and mice did
or did not produce antibodies in response to immunization with
simple polypeptide antigen
this immune responsiveness was an autosomal dominant trait mapped
to the MHC region
genes that controlled such immune response = Ir genes or immune
response genes
controlled the activation of helper T lymphocytes
necessary for antibody response to protein antigens
Parungao-Balolong 2011
5. INTRO...
• MHC: ROLE IN IMMUNE RESPONSE???
• 1970s : central role of MHC genes in immune
response to protein antigens was explained
• demonstrated that antigen specific T
lymphocytes do not recognize antigens in
free or soluble form but recognize portions
of protein antigens that are non-covalently
bound to MHC gene products
Parungao-Balolong 2011
6. INTRO...
MHC: TYPES OF GENE PRODUCTS
MHC Class I molecules
MHC Class II molecules
any given T cell recognizes foreign antigen bound to only
one specific class (I or II)
THUS : MHC molecules are integral components of the
ligands that T cell recognize
Parungao-Balolong 2011
7. IMPORTANCE
IMPORTANCE: specificity of T-lymphocytes for self MHC associated antigens?
1. MHC molecules are membrane - associated and not secreted : T-
lymphocytes can recognize foreign antigens only when bound to surfaces of
other cells
This limits T-cell activation such that T cells interact most effectively
with other cells that bear MHC-associated antigens and not with
soluble antigens (i.e antigen presentation)
The recognition of antigen on a cell surface also serves to localize the
effector functions of the activated T cell to the anatomic site of
antigen presentation
NOTE: In contrast, antibodies can function in the circulation by binding
to and neutralizing soluble antigens
Parungao-Balolong 2011
8. IMPORTANCE
IMPORTANCE: specificity of T-lymphocytes for self MHC
associated antigens?
2. the patterns of antigen association with class I or II
MHC molecules determine the kinds of T cells that are
stimulated by different forms of antigens
peptide fragments derived from extracellular proteins =
binds to class II
endogenously synthesized peptides = associates with
class I
Parungao-Balolong 2011
9. IMPORTANCE
IMPORTANCE: specificity of T-lymphocytes for self MHC
associated antigens?
3. the immune response to a foreign protein is determined by
the presence or absence of MHC molecules that can
bind and present fragments of that proteins to T cells
since MHC genes are polymorphic, many different alleles exist
within a population and these alleles differ in their ability to
bind and present different antigenic determinants of proteins
this is how MHC genes control immune responses to protein
antigens
Parungao-Balolong 2011
10. IMPORTANCE
IMPORTANCE: specificity of T-lymphocytes for self MHC associated
antigens?
4. Mature T cells in any individual recognize and respond to foreign
antigens but are responsive to self proteins
this antigen recognition is shaped by the selection of foreign antigen-
specific T cells from developing lymphocytes based on their
recognition of self MHC molecules with or without bound
peptide antigens
THUS, a second means by which MHC can influence immune responses
to particular antigens is through the role of MHC molecules in
shaping the repertoire of mature T cells
Parungao-Balolong 2011
11. DISCOVERY!
MURINE MHC
George Snell and colleagues
used classical genetic techniques to analyze
rejection of transplanted tumors and other
tissues (grafts)
examined the outcome of skin grafts between
individual animals using inbred strains of
laboratory mice
Parungao-Balolong 2011
12. DISCOVERY!
THE EXPERIMENT
principle: RECALL....
non-polymorphic: some genes are represented by only one normal nucleic
acid sequence
variant nucleic acid sequence is an uncommon mutation and may result in a
disease state
polymorphic: genes may vary at relatively high frequency among normal
individuals in the populations polymorphic
any individual animal can have the same allele at a genetic locus on both
chromosome of the pair (homozygous) or two different alleles one on each
chromosome (heterozygous)
Parungao-Balolong 2011
13. DISCOVERY!
THE EXPERIMENT
inbred mouse strains: produced by repetitive matings of siblings (> 20
generations)
every individual animal of a given inbred mouse strain will have identical nucleic
acid sequences at all locations on both members of each pair of chromosomes
completely homozygous at every genetic locus
genetically completely identical to every mouse of the same strain = syngeneic
THUS, when a tissue or organ, such as patch of skin, is grafted from one animal to
another, two possible outcomes may ensue:
grafted skin survives and functions as normal skin or;
immune system destroys the graft (graft rejection)
Parungao-Balolong 2011
14. DISCOVERY!
THE EXPERIMENT: genetic basis of graft rejection among inbred mice
1. grafts of skin from one animal to itself (isogeneic or isografts) or grafts
between animals of the same inbred strain (syngeneic grafts of syngrafts)
are usually NEVER rejected
2. grafts between animals of different inbred strains or between outbred
mice (allogeneic grafts or allografts) are almost ALWAYS rejected
Distinguishes the grafts as FOREIGN: the genes responsible for causing a
grafted tissue to be perceived as similar to one’s own tissue or as foreign
as called histocompatibility genes
differences between foreign and self were attributed to
genetic polymorphisms among diffrent histocompatibility
alleles
Parungao-Balolong 2011
15. DISCOVERY!
THE CONGENEIC MOUSE STRAINS EXPERIMENT
differed only by genes responsible for graft rejection (MHC)
NOTE: although several different genes could contribute to rejection, a single genetic region is
responsible for most rejection phenomena
this gene encodes a polymorphic blood group antigen called antigen II or
histocompatibility-2 (H-2)
JUSTIFICATION
initially, MHC congeneic strains were thought to differ at a single locus
occasional recombination events occurred within the MHC during interbreeding of different
strains, suggesting that the MHC actually contained several different genes, each involved in graft
rejection
H-2 region is now known to be homologous to genes that determine the fate of grafted
tissues in other species (Major Histocompatibility Complex)
Parungao-Balolong 2011
16. DISCOVERY!
GENETICS OF GRAFT REJECTION
indicated that the products of MHC genes are co-
dominantly expressed
alleles on both chromosomes of a pair are
expressed
as a consequence, each parent of a genetic cross
between two different strains can reject a graft
from the offspring by recognizing MHC
alleles inherited from the other parent
Parungao-Balolong 2011
17. DISCOVERY!
SEROLOGIC STUDIES IN HUMANS (Dausett et al)
development of allogeneic blood transfusion and allogeneic organ transplantation in clinical medicine
provided ways to detect and define genes that control rejection in humans
OBSERVATIONS: patients who rejected kidneys or had transfusion reactions to WBC often develops
circulating antibodies reactive with antigens on the WBC of the blood or organ donor
in the presence of complement, the recipient’s serum would lyse lymphocytes obtained from the donor
and also lyse lymphocytes obtained from some but not all third parties (individuals other than the blood
or organ donor or the recipient)
this sera which react against cells of allogeneic individuals are called alloantisera or
allosera
said to contain alloantibodies whose molecular targets are alloantigens (HLA)
HLA or human leukocyte antigens: products of polymorphic genes that distinguish foreign tissues
from self
HLAs = H-2 in mice = MHC
Parungao-Balolong 2011
18. Structure
and Function
Larger chain: alpha 1, 2 and 3 domain
alpha 3-domain is an immunoglobulin fold and is the
attachment point to the membrane
alpha 1 and 2 domain forms an 8-stranded β-sheet that
serves as a platform for peptide binding.
Edges of the peptide binding site are defined by long a -
helices, one from a 1 and one from a 2
alpha 3 is paired with β2 microglobulin, which also has a
typical Ig fold
β2 microglobulin is essential for stability and peptide
binding
CD8 on TC cells binds to the alpha domain
Parungao-Balolong 2011
19. FUNCTION and PRODUCTION Parungao-Balolong 2011
PRODUCTION
The peptides are mainly generated in the cytosol by the
proteasome
proteasome degrades intracellular proteins into small
peptides that are then released into the cytosol
The peptides have to be translocated from the cytosol
into the (ER) to meet the MHC class I molecule, whose
peptide-binding site is in the lumen of the ER
FUNCTION
display fragments of proteins from within the cell to T cells
healthy cells will be ignored while cells containing foreign proteins will be attacked by the
immune system
Because MHC class I molecules present peptides derived from cytosolic proteins, the
pathway of MHC class I presentation is often called the cytosolic or endogenous pathway
20. The peptide translocation from the
cytosol into the lumen of the ER is
accomplished by the transporter TRANSLOCATION
associated with antigen processing (TAP)
= TAP 1 and 2
The two subunits form a peptide binding
site and two ATP binding sites that face
the lumen of the cytosol
TAP binds peptides on the cytoplasmic
site and translocates them under ATP
consumption into the lumen of the ER
The MHC class I molecule is then in turn
loaded with peptides in the lumen of the
ER
The peptide-loading process involves
several other molecules that form a large
multimeric complex consisting of TAP,
tapasin, calreticulin, calnexin, and ERP57
Parungao-Balolong 2011
21. Once the peptide is loaded onto
the MHC class I molecule, it TRANSLOCATION
leaves the ER through the
secretory pathway to reach the
cell surface
The transport of the MHC class I
molecules through the secretory
pathway involves several post-
translational modifications of the
MHC molecule
example: change to the N-glycan
regions of the protein, followed
by extensive changes to the N-
glycans in the Golgi apparatus
Parungao-Balolong 2011
22. GENES AND
ISOTYPES
Very Less
polymorphic polymorphic
HLA-A (HLA-A) HLA-E (HLA-E)
HLA-B (HLA-B) HLA-F (HLA-F)
HLA-C (HLA-C) HLA-G (HLA-
G)
HLA-K
HLA-L
Parungao-Balolong 2011
23. Structure
and Function
Almost identically sized a and b chains
Each chain is divided into two segments, e.g. alpha 1
and 2; beta 1 and 2
alpha 2 and beta 2 are immunoglobulin domains that
pair with each other
alpha 2 and beta 2 are the point of membrane
attachment
alpha 1 and beta 1 form the peptide binding domain,
conformation quite similar to Class I MHC, except,
the ends are open allowing the binding of longer
peptides
CD4 on TH cells binds to beta 2 domain
Parungao-Balolong 2011
24. FUNCTION
found only on a few specialized cell types, including
macrophages, dendritic cells and B cells, all
of which are professional antigen-
presenting cells (APCs)
The peptides presented by class II molecules are
derived from extracellular proteins (not cytosolic as
in class I)
MHC class II-dependent pathway of antigen
presentation is called the endocytic or
exogenous pathway
Loading of class II molecules: extracellular proteins
are endocytosed, digested in lysosomes, and bound
by the class II MHC molecule prior to the molecule's
migration to the plasma membrane
Parungao-Balolong 2011
25. SYNTHESIS
result of dimerization of α and β chains, with the assistance of an invariant chain =
a special polypeptide involved in the formation and deliverance of MHC class II
protein
The nascent MHC class II protein in the rough ER has its peptide-binding cleft
blocked by the invariant chain (Ii; a trimer) to prevent it from binding cellular
peptides or peptides from the endogenous pathway
The invariant chain also facilitates MHC class II's export from the ER in a vesicle
which fuses with a late endosome containing the endocytosed, degraded proteins
It is then broken down in stages, leaving only a small fragment called CLIP which
still blocks the peptide binding cleft
An MHC class II-like structure, HLA-DM, removes CLIP and replaces it with a
peptide from the endosome
The stable MHC class-II is then presented on the cell surface
Parungao-Balolong 2011
27. Characteristic MHC-I pathway MHC-II pathway
Polymorphic chain α and β2
Composition of the stable Polymorphic chains α and β, peptide
microglobulin, peptide bound to α
peptide-MHC complex binds to both
chain
Dendritic cells, mononuclear
Types of antigen presenting
cells (APC) All nucleated cells phagocytes, B lymphocytes, some
endothelial cells, epithelium of thymus
T lymphocytes able to Cytotoxic T lymphocytes Helper T lymphocytes
respond (CD8+) (CD4+)
cytosolic proteins (mostly synthetized Proteins present in endosomes or
Origin of antigenic
by the cell; may also enter from the lysosomes (mostly internalized from
proteins extracellular medium via phagosomes) extracellular medium)
Enzymes responsible for Proteases from endosomes and
peptide generation Cytosolic proteasome lysosomes (for instance, cathepsin)
Location of loading the Specialized vesicular
peptide on the MHC molecule Endoplasmic reticulum
compartment
Molecules implicated in
transporting the peptides and TAP (transporter associated with
loading them on the MHC antigen processing) DM, invariant chain
molecules
28. IMPORTANT ASPECTS
OF THE MHC
• High polymorphism in MHC for • NO recombination mechanisms
a species for creating diversity in MHC
• Alleles for MHC genes are co- • Peptide must bind with
dominant individual’s MHC to induce
immune response
• Each MHC gene product is
expressed on surface of • MHC molecules are membrane-
individual cell bound
• Each MHC has ONE peptide • Recognition by Ts requires cell-
binding site but each MHC can cell contact
bind many different peptide one
at a time (Peptide binding is
“degenerate”)
• Mature Ts must have TCR that
recognizes particular MHC
Parungao-Balolong 2011
29. T-CELL RECEPTOR (TCR)
• role in immune response
• Surface molecule on Ts
• Recognize Ag presented in MHC
context
• Similar to Immunoglobulin
• Two types of TCR
• α β: predominant in lymphoid
tissues
• γ δ: enriched at mucosal surfaces
Parungao-Balolong 2011
30. IMPORTANT ASPECTS
OF TCR
• Each T cell has TCR of only ONE specificity
• Allelic exclusion
• αβ TCR recognizes Ag only in the context of cell-cell
interaction and in correct MHC context
• γδ TCR recognizes Ag in MHC-independent manner
• Response to certain viral and bacterial Ag
Parungao-Balolong 2011
31. GENETIC
BASIS FOR
RECEPTOR
GENERATION
• Accomplished by recombination of V, D and J gene
segments
• TCR β chain genes have V, D, and J
• TCR α chain genes have V and J
Parungao-Balolong 2011
32. TCR AND CD3
• TCR is closely associated
with CD3 complex
• Group of 5 proteins
• Commonly called
“invariant” chains of TCR
• Role of CD3 complex
• CD3 necessary for cell
surface expression of TCR
• transduces signal after Ag
interaction with TCR Parungao-Balolong 2011
34. NICE TO KNOW
(from wikipedia
though...)
• MHC and Sexual Selection
• MHC plays a role in the selection of potential mates, via olfaction
• MHC genes make molecules that enable the immune system to
recognize invaders; in general, the more diverse the MHC genes of
the parents the stronger the immune system of the offspring
• It would be beneficial, therefore, to have evolved systems of
recognizing individuals with different MHC genes and preferentially
selecting them to breed with
Parungao-Balolong 2011
35. NICE TO KNOW
(from wikipedia
though...)
• MHC and Sexual Selection
• Yamazaki et al. (1976) showed this to be the case for male mice, which show a
preference for females of different MHC; similar results have been obtained with fish
• Claus Wedekind (1995) determined MHC-dissimilar mate selection tendencies in
humans
• group of female college students smelled t-shirts that had been worn by male
students for two nights, without deodorant, cologne, or scented soaps
• An overwhelming number of women preferred the odors of men with dissimilar
MHCs to their own
• preference was reversed if they were taking oral contraceptives
• Rates of early pregnancy loss are lower in couples with dissimilar MHC genes
Parungao-Balolong 2011
36. • Describe the immune ASSIGNMENT
response to:
: WORK IN
• A bacterial infection in your PAIRS
arm
• A bacterial infection from
your intestinal tract
• A viral infection
• A cancerous cell in your
body
• Which MHC type is most
likely to be involved?
Parungao-Balolong 2011