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.
it is related to immunology .. Major histo compatibility complex - a highly polymorphic region on chromosome 6 with genes particularly involved in immune functions..
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.
Major Histocompatibility Complex (MHC) molecules present antigen fragments to antigen-sensitive cells like T cells. There are three main classes of MHC molecules - Class I presents endogenous antigens to cytotoxic T cells, Class II presents exogenous antigens to helper T cells, and Class III encodes complement proteins and cytokines. MHC molecules play a key role in the immune system by regulating antigen presentation and immune responses.
An antigen is any substance that reacts with lymphocytes, while immunogens generate immune responses. Haptens are small molecules that require coupling to carriers to induce responses. Antibody-antigen binding depends on weak interactions between sites on antibodies and epitopes on antigens. Antibodies are produced with a wide variety of binding sites to recognize different antigenic determinants. Factors like foreignness, size, structure, and route of administration influence a substance's immunogenicity.
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 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 discusses major histocompatibility complexes (MHCs), which are glycoproteins found on cell surfaces that present antigen fragments to T cells. It describes MHC Class I and Class II molecules, which present antigens from intracellular and extracellular pathogens, respectively. MHC genes were first identified as important in tissue graft rejection and show high polymorphism between individuals.
This document contains lecture notes on major histocompatibility complex (MHC) and related topics from a biotechnology course. It discusses antigen-presenting cells, the structure and function of MHC class I and II molecules, similarities and differences between the two classes, MHC-associated genes, and important immune signaling molecules like cytokines, interleukins, interferons, and chemokines. Diagrams are included to illustrate MHC pathway and types of interferons. The notes provide an overview of key concepts in MHC and immunology for students in the biotechnology course.
it is related to immunology .. Major histo compatibility complex - a highly polymorphic region on chromosome 6 with genes particularly involved in immune functions..
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.
Major Histocompatibility Complex (MHC) molecules present antigen fragments to antigen-sensitive cells like T cells. There are three main classes of MHC molecules - Class I presents endogenous antigens to cytotoxic T cells, Class II presents exogenous antigens to helper T cells, and Class III encodes complement proteins and cytokines. MHC molecules play a key role in the immune system by regulating antigen presentation and immune responses.
An antigen is any substance that reacts with lymphocytes, while immunogens generate immune responses. Haptens are small molecules that require coupling to carriers to induce responses. Antibody-antigen binding depends on weak interactions between sites on antibodies and epitopes on antigens. Antibodies are produced with a wide variety of binding sites to recognize different antigenic determinants. Factors like foreignness, size, structure, and route of administration influence a substance's immunogenicity.
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 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 discusses major histocompatibility complexes (MHCs), which are glycoproteins found on cell surfaces that present antigen fragments to T cells. It describes MHC Class I and Class II molecules, which present antigens from intracellular and extracellular pathogens, respectively. MHC genes were first identified as important in tissue graft rejection and show high polymorphism between individuals.
This document contains lecture notes on major histocompatibility complex (MHC) and related topics from a biotechnology course. It discusses antigen-presenting cells, the structure and function of MHC class I and II molecules, similarities and differences between the two classes, MHC-associated genes, and important immune signaling molecules like cytokines, interleukins, interferons, and chemokines. Diagrams are included to illustrate MHC pathway and types of interferons. The notes provide an overview of key concepts in MHC and immunology for students in the biotechnology course.
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.
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.
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.
Major Histocompatibility complex & Antigen Presentation and ProcessingSreeraj Thamban
The document discusses the major histocompatibility complex (MHC) and antigen processing and presentation. It describes MHC molecules as polymorphic glycoproteins that play a role in discriminating self from non-self and participate in both humoral and cell-mediated immunity. MHC class I molecules present endogenous antigens on most nucleated cells and interact with CD8+ T cells. MHC class II molecules present exogenous antigens on antigen-presenting cells and interact with CD4+ T cells. Antigens are processed into peptides of appropriate size and bound motifs to be presented in the binding groove of MHC molecules.
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,
This document summarizes antigen processing and presentation. It discusses that antigen presenting cells such as macrophages, dendritic cells, and B cells express class II MHC molecules and provide co-stimulatory signals to activate T helper cells. These cells internalize antigens through phagocytosis or endocytosis, degrade them into peptides, and present the peptides bound to class II MHC on their surface. The document also describes the major histocompatibility complex and the roles of class I and class II MHC molecules in antigen presentation to T cells. It outlines the exogenous and endogenous antigen processing pathways, how exogenous antigens are presented by class II MHC and endogenous antigens by class I MHC.
The document summarizes key concepts about the major histocompatibility complex (MHC):
1) The MHC was discovered through studies of transplant rejection in mice, which showed that rejection was dependent on the genetics of the donor and recipient strains.
2) MHC molecules present peptide antigens to T cells and play a key role in immune responses, including transplant rejection.
3) MHC molecules are highly polymorphic, with many variants within populations, in order to allow populations to recognize a wide variety of pathogens.
Antigen processing and presentation involves two pathways: 1) Exogenous antigens are internalized, processed in the endosome, and presented on MHC class II to CD4+ T cells. 2) Endogenous antigens are processed by the proteasome in the cytosol, transported to the ER by TAP, loaded onto MHC class I, and presented to CD8+ T cells. For an immune response, antigen must be degraded into peptides and bound to MHC molecules on antigen presenting cells to activate T cells through TCR recognition and co-stimulation.
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 discusses the major histocompatibility complex (MHC), which consists of glycoproteins found on cell surfaces that present antigens to T cells. MHC molecules are divided into class I and class II. Class I molecules are found on all nucleated cells and present antigens to CD8+ T cells, while class II molecules are found on antigen-presenting cells and present antigens to CD4+ T cells. The MHC was first identified as important for tissue graft compatibility.
Advanced Immunology: Antigen Processing and PresentationHercolanium GDeath
1. Antigens are internalized by antigen presenting cells through endocytosis and degraded within lysosomes into peptide fragments.
2. Peptide fragments from extracellular antigens bind to MHC class II molecules within antigen processing vesicles. The vesicles containing MHC class II-peptide complexes fuse with the cell membrane and present the complexes to CD4+ T cells.
3. Peptide fragments from intracellular antigens are degraded by the proteasome and transported into the endoplasmic reticulum by TAP proteins. The peptides bind to MHC class I molecules and the complexes are presented on the cell surface to CD8+ T cells.
The major histocompatibility complex (MHC) genes code for human leukocyte antigens (HLA) that regulate the immune system and present antigens. MHC is divided into three classes, with class I and II expressing different HLA molecules. HLA is highly polymorphic, contributing to genetic diversity and differences in susceptibility to infectious diseases among populations. Certain HLA variants are associated with increased or decreased risk of developing tuberculosis. Understanding how HLA influences immune responses to infections could help develop future vaccines that target HLA-associated peptides.
Impact of MHC class I diversity on immune control of Immuno-deficiency virus ...Ramesh Pothuraju
This document summarizes a presentation on the impact of MHC class I diversity on immune control of HIV replication. It discusses how MHC class I molecules present antigens to T cells, and their role in distinguishing self from non-self. It then focuses on the central role of MHC class I molecules, particularly HLA-B alleles, in controlling HIV viral loads through CD8+ T cell responses targeting conserved HIV proteins like Gag. Polyfunctional and HLA-B restricted CD8+ T cell responses targeting Gag seem to be most effective at control of HIV replication.
The major histocompatibility complex (MHC) is a set of genes that code for cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates. Peptides from intracellular pathogens are carried to the cell surface by MHC class I and MHC class II and presented to CD4 T cells. Antigen presenting cells like dendritic cells, macrophages, and B cells present MHC class II antigens to CD4 T cells, while all nucleated cells present MHC class I antigens.
The document summarizes antigen processing and presentation by cells. It describes how T lymphocytes recognize short peptide antigens displayed by MHC molecules on antigen-presenting cells. Dendritic cells are specialized to capture antigens through receptors and transport them to lymph nodes for presentation to T cells. Proteins are broken down by proteasomes and cathepsins into peptides that bind MHC class I and class II, respectively, for recognition by CD8+ and CD4+ T cells.
T cells are activated through the recognition of antigen peptides presented on MHC complexes on antigen presenting cells (APCs). This leads to T cell proliferation and differentiation into effector T cells. Cytotoxic T cells recognize endogenous antigens on MHC I to kill infected cells, while helper T cells recognize exogenous peptides on MHC II and secrete cytokines to stimulate macrophage activation or B cell antibody production. Full T cell activation requires both antigen recognition by the TCR and co-stimulatory signaling between molecules such as B7 and CD28.
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.
02.18.09: Review: Type 1 Diabetes and Overview of Immune ResponseOpen.Michigan
Slideshow is from the University of Michigan Medical
School's M1 Immunology sequence
View additional course materials on Open.Michigan:
openmi.ch/med-M1Immunology
Diagnostic electrophysiology (ep) catheters global trends, estimates and fo...Research Hub
The document summarizes a report on the global diagnostic electrophysiology catheters market. Some key points:
- The global market is projected to reach $3.5 billion by 2016, with North America and Europe currently accounting for over 60% of the market. Asia-Pacific is the fastest growing region.
- Conventional EP diagnostic catheters have over 40% of the global market share currently.
- The report analyzes the market size, trends, growth rates, investment opportunities, and major players in the diagnostic electrophysiology catheters industry from 2012-2018. It provides a detailed segmentation of the market by region and product type.
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.
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.
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.
Major Histocompatibility complex & Antigen Presentation and ProcessingSreeraj Thamban
The document discusses the major histocompatibility complex (MHC) and antigen processing and presentation. It describes MHC molecules as polymorphic glycoproteins that play a role in discriminating self from non-self and participate in both humoral and cell-mediated immunity. MHC class I molecules present endogenous antigens on most nucleated cells and interact with CD8+ T cells. MHC class II molecules present exogenous antigens on antigen-presenting cells and interact with CD4+ T cells. Antigens are processed into peptides of appropriate size and bound motifs to be presented in the binding groove of MHC molecules.
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,
This document summarizes antigen processing and presentation. It discusses that antigen presenting cells such as macrophages, dendritic cells, and B cells express class II MHC molecules and provide co-stimulatory signals to activate T helper cells. These cells internalize antigens through phagocytosis or endocytosis, degrade them into peptides, and present the peptides bound to class II MHC on their surface. The document also describes the major histocompatibility complex and the roles of class I and class II MHC molecules in antigen presentation to T cells. It outlines the exogenous and endogenous antigen processing pathways, how exogenous antigens are presented by class II MHC and endogenous antigens by class I MHC.
The document summarizes key concepts about the major histocompatibility complex (MHC):
1) The MHC was discovered through studies of transplant rejection in mice, which showed that rejection was dependent on the genetics of the donor and recipient strains.
2) MHC molecules present peptide antigens to T cells and play a key role in immune responses, including transplant rejection.
3) MHC molecules are highly polymorphic, with many variants within populations, in order to allow populations to recognize a wide variety of pathogens.
Antigen processing and presentation involves two pathways: 1) Exogenous antigens are internalized, processed in the endosome, and presented on MHC class II to CD4+ T cells. 2) Endogenous antigens are processed by the proteasome in the cytosol, transported to the ER by TAP, loaded onto MHC class I, and presented to CD8+ T cells. For an immune response, antigen must be degraded into peptides and bound to MHC molecules on antigen presenting cells to activate T cells through TCR recognition and co-stimulation.
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 discusses the major histocompatibility complex (MHC), which consists of glycoproteins found on cell surfaces that present antigens to T cells. MHC molecules are divided into class I and class II. Class I molecules are found on all nucleated cells and present antigens to CD8+ T cells, while class II molecules are found on antigen-presenting cells and present antigens to CD4+ T cells. The MHC was first identified as important for tissue graft compatibility.
Advanced Immunology: Antigen Processing and PresentationHercolanium GDeath
1. Antigens are internalized by antigen presenting cells through endocytosis and degraded within lysosomes into peptide fragments.
2. Peptide fragments from extracellular antigens bind to MHC class II molecules within antigen processing vesicles. The vesicles containing MHC class II-peptide complexes fuse with the cell membrane and present the complexes to CD4+ T cells.
3. Peptide fragments from intracellular antigens are degraded by the proteasome and transported into the endoplasmic reticulum by TAP proteins. The peptides bind to MHC class I molecules and the complexes are presented on the cell surface to CD8+ T cells.
The major histocompatibility complex (MHC) genes code for human leukocyte antigens (HLA) that regulate the immune system and present antigens. MHC is divided into three classes, with class I and II expressing different HLA molecules. HLA is highly polymorphic, contributing to genetic diversity and differences in susceptibility to infectious diseases among populations. Certain HLA variants are associated with increased or decreased risk of developing tuberculosis. Understanding how HLA influences immune responses to infections could help develop future vaccines that target HLA-associated peptides.
Impact of MHC class I diversity on immune control of Immuno-deficiency virus ...Ramesh Pothuraju
This document summarizes a presentation on the impact of MHC class I diversity on immune control of HIV replication. It discusses how MHC class I molecules present antigens to T cells, and their role in distinguishing self from non-self. It then focuses on the central role of MHC class I molecules, particularly HLA-B alleles, in controlling HIV viral loads through CD8+ T cell responses targeting conserved HIV proteins like Gag. Polyfunctional and HLA-B restricted CD8+ T cell responses targeting Gag seem to be most effective at control of HIV replication.
The major histocompatibility complex (MHC) is a set of genes that code for cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates. Peptides from intracellular pathogens are carried to the cell surface by MHC class I and MHC class II and presented to CD4 T cells. Antigen presenting cells like dendritic cells, macrophages, and B cells present MHC class II antigens to CD4 T cells, while all nucleated cells present MHC class I antigens.
The document summarizes antigen processing and presentation by cells. It describes how T lymphocytes recognize short peptide antigens displayed by MHC molecules on antigen-presenting cells. Dendritic cells are specialized to capture antigens through receptors and transport them to lymph nodes for presentation to T cells. Proteins are broken down by proteasomes and cathepsins into peptides that bind MHC class I and class II, respectively, for recognition by CD8+ and CD4+ T cells.
T cells are activated through the recognition of antigen peptides presented on MHC complexes on antigen presenting cells (APCs). This leads to T cell proliferation and differentiation into effector T cells. Cytotoxic T cells recognize endogenous antigens on MHC I to kill infected cells, while helper T cells recognize exogenous peptides on MHC II and secrete cytokines to stimulate macrophage activation or B cell antibody production. Full T cell activation requires both antigen recognition by the TCR and co-stimulatory signaling between molecules such as B7 and CD28.
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.
02.18.09: Review: Type 1 Diabetes and Overview of Immune ResponseOpen.Michigan
Slideshow is from the University of Michigan Medical
School's M1 Immunology sequence
View additional course materials on Open.Michigan:
openmi.ch/med-M1Immunology
Diagnostic electrophysiology (ep) catheters global trends, estimates and fo...Research Hub
The document summarizes a report on the global diagnostic electrophysiology catheters market. Some key points:
- The global market is projected to reach $3.5 billion by 2016, with North America and Europe currently accounting for over 60% of the market. Asia-Pacific is the fastest growing region.
- Conventional EP diagnostic catheters have over 40% of the global market share currently.
- The report analyzes the market size, trends, growth rates, investment opportunities, and major players in the diagnostic electrophysiology catheters industry from 2012-2018. It provides a detailed segmentation of the market by region and product type.
2012 deep research report on china influenza vaccine industrysmarter2011
This 144-page report from QY Research Group analyzes the China influenza vaccine industry. It profiles 16 domestic and international manufacturers. It provides data on industry capacity, production, costs, profits from 2009-2016. It also examines market trends, including growing demand in China driven by increasing vaccination rates and an aging population. The report concludes with a feasibility analysis for an 8 million dose per year influenza vaccine project in China.
Este documento describe la importancia de la programación en la carrera de ingeniería de mantenimiento mecánico. Explica que el mantenimiento mecánico involucra reparar maquinaria para extender su vida útil usando herramientas como la programación. La programación es una valiosa herramienta debido al avance tecnológico, permitiendo crear software y herramientas para el mantenimiento de equipos y diseñar programas para evaluar su funcionamiento y desgaste. Conocer lenguajes de programación facilita crear aplicaciones y
This document provides information about an oncology social worker and their role. It discusses what an oncology social worker sees, hears, and feels in working with cancer patients. It outlines the types of support oncology social workers provide, including emotional support, practical assistance, information, and advocacy. It also summarizes the standards and scope of practice for oncology social work according to the Association of Oncology Social Work. Finally, it discusses common issues cancer survivors face and encourages patients to take advantage of oncology social work services.
This document is Vascular Solutions' 10-Q filing for the quarter ended March 31, 2009. It includes:
1) Consolidated balance sheets showing total assets of $44.9 million as of March 31, 2009 including $8.1 million in cash and $30.9 million in current assets. Total liabilities were $6.7 million in current liabilities.
2) Consolidated statements of operations showing revenue increased to $15.8 million for the quarter including $15.4 million in product revenue. Cost of goods sold was $5.2 million and net loss was $939,000.
3) Notes to the unaudited consolidated financial statements providing additional details
El documento contiene una serie de frases y oraciones cortas sobre diversos temas, incluyendo fotografías, viajes, comida, bebidas alcohólicas, partes del cuerpo y personas. Finaliza abruptamente sin contexto que una las ideas.
This curriculum vitae outlines the professional experience and qualifications of Dr. David R. Silvers, including his education, medical licensure and certifications, academic appointments, hospital affiliations, publications, and presentations. He received his M.D. from Tulane University School of Medicine in 1979 and has since maintained active staff positions at several hospitals. His areas of specialty include gastroenterology and he has served in leadership roles such as chief of staff and department chair.
The National Corporate Sponsorship Program was established to develop formal alliances that involve Corporate America more closely with BDPA programs, activities and goals. Corporate sponsors not only offer financial support but also participate in programs developed to enhance the technical and professional skills of the community. The investment in BDPA creates positive exposure to a technically diverse membership of African-American Information Technology professionals and students.
The program is designed to offer corporations an opportunity to partner with BDPA to meet corporate goals and objectives for recruiting, employee development, philanthropic endeavors and enhanced image in the African American Community. The program is open to all corporations with a sincere interest in pursuing the vision, mission, objectives and goals of BDPA.
The conceptual and fundamental scope of the program is to:
• Link BDPA strategic initiatives to the objectives of the corporation
• Document mutual understanding, measurements and goals
• Develop plans, assign resources and confirm milestones for viewing progress toward the goals
• Provide a forum to interact with other IT and HR industry leaders and professionals
• Increase exposure opportunities to technically competent and diverse IT professionals and students
• Enhance loyalty in the corporation amongst employees and customers
In order to pull together all the components of a successful program, BDPA partners with corporations, associations and other strategic alliance partners, but by far, corporate support is a major component of BDPA’s success. Sponsoring levels available are listed below and opportunities are detailed in our comprehensive corporate sponsorship portfolio. (2013 Corporate Opportunities Portfolio.pdf)
• Platinum Corporate Sponsor $100,000+
• Gold Corporate Sponsor $50,000+
• Silver Corporate Sponsor $25,000+
• Bronze Corporate Sponsor $10,000+
• Corporate Sponsor $ 5,000+
• Corporate Supporter Less than $5,000
Contact us by email (corpsales@bdpa.org) or phone (301.584-3135) for more details on our corporate sponsorship program.
We initiate coverage of Exista with a Buy rating and a target price of ISK 38.1 per share, implying upside potential of 25% from the current share price. We believe Exista has positioned itself well through its strategic holdings in Sampo and Kaupthing, which provide opportunities for expansion into the Nordic financial market. The operational arm gives Exista steady cash flow and reserves to support its investment activities. While market risk and concentration risk are concerns, we are optimistic about recovery in financial markets and opportunities for Exista.
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.
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.
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.
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 histocompatility complex (Antigen Presentation to T cells, Autoimmunity...Pradeep Singh Narwat
The document provides an overview of major histocompatibility complex (MHC) molecules, including their history, structure, organization and inheritance, and functions in antigen presentation and immune responses. MHC molecules are membrane-bound glycoproteins that are encoded by genes in the MHC locus and present antigen peptides to T cells to initiate adaptive immune responses against intracellular and extracellular pathogens.
The major histocompatibility complex (MHC) contains genes that encode antigen-presenting molecules. MHC molecules present antigens to T cells, triggering immune responses. MHC genes are highly polymorphic within populations and vary in number between species. This polymorphism is maintained by heterozygote advantage, allowing populations to respond to a diverse range of pathogens. Specific MHC alleles are associated with resistance or susceptibility to various infectious and autoimmune diseases in different mammal species. MHC molecules also influence individual odors, potentially affecting mate choice.
The major histocompatibility complex (MHC) is a cluster of genes found in mammals that plays a key role in the immune system by helping the body distinguish self from non-self. The MHC was discovered through studies of inbred mouse strains and includes polymorphic glycoproteins divided into three main classes. MHC Class I and II are best known for presenting antigen peptides and interacting with T-cell receptors. Genes in the MHC are highly polymorphic, linked, and inherited as haplotypes from each parent. This polymorphism allows recognition of a diverse range of antigens and is advantageous for the immune system.
Immunogens or antigens are foreign substances that elicit an immune response when introduced to the body. They are recognized by antibodies or T-lymphocytes. Immunogens can induce antibody formation themselves, while haptens require a carrier molecule to produce an immune response. Antigens are presented on antigen-presenting cells and recognized by B and T cells, initiating humoral or cell-mediated immunity. Exogenous antigens from bacteria, viruses, and other external sources are phagocytosed and processed, while endogenous antigens from infection or autoimmunity are presented via MHC I molecules.
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.
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.
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 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 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 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.
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.
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.
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.
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