SIMILARITIES BETWEEN CLASS I AND CLASS II
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Both MHC class I and class II are synthesized in the rough endoplasmic reticulum, found on the surface of antigen presenting cells, and their expression is co-dominant. MHC class I presents endogenous antigens to CD8 T cells and binds peptides of 8-10 amino acids, while MHC class II presents exogenous antigens to CD4 T cells and binds peptides of 13-18 amino acids. After binding, MHC class I triggers lysis of infected cells by cytokines, while MHC class II triggers antibody formation by B cells.
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- Mature B cells exit the bone marrow with the ability to bind antigen, and mechanisms exist to ensure tolerance by deleting or anergizing self-reactive B cells.
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2) Helper T cells recognize antigens presented by antigen-presenting cells and activate other immune cells like B cells and cytotoxic T cells. Cytotoxic T cells directly kill infected cells.
3) B cells produce antibodies that target extracellular pathogens. Upon activation by helper T cells, B cells differentiate into plasma cells that secrete large amounts of antibodies, establishing antibody-mediated immunity.
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Activation of T and B Cells
1. The document presents information about T cells and B cells, including their development, activation, and functions.
2. T cells develop in the thymus gland and have roles in direct killing of infected cells and regulating the immune response. B cells mature in the bone marrow and produce antibodies to help fight pathogens.
3. Activation of both T and B cells involves interaction with antigen-presenting cells and costimulatory signals, leading to cell proliferation and differentiation into effector and memory cells.
Hypersensitivity
This document discusses the four main types of hypersensitivity reactions:
Type I is an immediate reaction mediated by IgE antibodies. It causes conditions like allergic asthma.
Type II involves antibodies binding to antigens on a person's own cells, activating complement and causing cell lysis. It includes conditions like autoimmune hemolytic anemia.
Type III occurs when immune complexes are deposited in tissues, activating complement and causing inflammation and tissue damage. Examples are serum sickness and lupus nephritis.
Type IV is a delayed reaction mediated by T cells and monocytes/macrophages. It causes conditions like contact dermatitis and tuberculosis.
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Antibodies, also known as immunoglobulins, are Y-shaped glycoproteins produced by plasma cells that recognize and bind to specific antigens. They have a variable region that binds to antigens and a constant region that interacts with other immune system components. The five main classes of antibodies are IgG, IgM, IgA, IgD, and IgE, which differ in structure and function. Antibodies play a key role in humoral immunity by neutralizing pathogens, agglutinating foreign cells, and activating the complement system and effector cells of the immune system.
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B-cell activation can occur through two routes - dependent or independent of T helper cells. T-helper cells interact with antigen-bound B-cells via CD40/CD40L and B7-CD28 costimulation, releasing cytokines that cause the B-cell to proliferate and differentiate into a plasma cell. The interaction of cytokines and proliferation factors released by T-helper cells provides signals needed for B-cell proliferation and class switching.
T-cell activation requires interaction between the TCR and antigen-bound MHC on an antigen presenting cell, as well as CD28-B7 costimulation, which causes cytokine release and leads to T-cell proliferation, clonal expansion, and differentiation into memory and
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2. Antigens are processed through different pathways depending on if they are intracellular or extracellular. Intracellular antigens are degraded by the proteasome and transported into the ER by TAP to bind class I MHC. Extracellular antigens are endocytosed and degraded in lysosomes to bind class II MHC.
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B-cell and humoral immunity
B-cells develop and mature in the bone marrow from stem cells through distinct stages marked by specific cell surface markers and patterns of immunoglobulin gene expression. Mature B-cells leave the bone marrow and travel to peripheral lymphoid tissues where they are activated upon encountering antigen to produce plasma cells that secrete antibodies and memory B-cells. B-cell activation involves proliferation, somatic hypermutation, selection, and potential class switching in germinal centers to produce high affinity antibodies and long-lasting immunological memory. This allows for a rapid secondary immune response upon re-exposure to the same antigen.
Haptens
Haptens are small molecules that are antigenic but not immunogenic on their own. They are unable to induce an immune response because they cannot activate helper T cells due to their inability to bind MHC proteins or activate B cells directly as they are univalent. However, when haptens are covalently bound to a carrier protein, they form immunogenic conjugates that can induce an immune response by activating helper T cells and B cells. Pioneering work by Karl Landsteiner demonstrated that antibodies produced against hapten-carrier conjugates were specific for the hapten and carrier epitopes. Common examples of haptens include drug molecules, peptides, and steroids. Hapten-protein conjugates can cause drug
Major Histocompatibility Complex (MHC)
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.
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T-lymphocytes and generation
The document discusses T lymphocytes and their generation, maturation, activation, and differentiation. It provides details on:
1) T-lymphocytes mature in the thymus gland and express T-cell receptors that recognize antigens bound to MHC molecules. They differentiate into helper T-cells, cytotoxic T-cells, memory T-cells, and regulatory T-cells.
2) T-cell receptors are composed of alpha and beta chains that undergo gene rearrangement during development.
3) T-cells mature through double negative, double positive, and single positive stages in the thymus, undergoing positive and negative selection to remove self-reactive cells.
T CELL RECEPTOR.pptx
The T cell receptor (TCR) is a protein complex found on the surface of T cells that is responsible for recognizing fragments of antigen bound to MHC molecules. It consists of an alpha and beta chain, with 95% of T cells containing these chains and 5% containing gamma and delta chains instead. Each chain contains a variable region that binds the peptide-MHC complex and a constant region near the cell membrane. The variable regions contain three hypervariable complementarity-determining regions important for antigen recognition. The TCR is associated with CD3 proteins that transmit activation signals into the T cell upon peptide binding. TCR diversity arises from genetic recombination of DNA segments during T cell development.
B Cell Development
The document discusses B cell development in the bone marrow. Key points:
- B cell development starts in the fetal liver and continues in the bone marrow post-birth, where it undergoes various stages defined by immunoglobulin gene rearrangements.
- Ligation of the pre-B cell receptor by an unknown ligand is essential, as it ensures each cell expresses only one antibody specificity via allelic exclusion and drives proliferation of pre-B cells.
- Mature B cells exit the bone marrow with the ability to bind antigen, and mechanisms exist to ensure tolerance by deleting or anergizing self-reactive B cells.
Tcr class
T-cell receptors are heterodimers consisting of alpha and beta chains with variable and constant regions. The variable region binds to antigens presented by the major histocompatibility complex and contains complementary determining regions that provide specificity. While the TCR is responsible for antigen recognition, it does not signal within the cell itself. Signal transduction is carried out by the CD3 complex, which contains gamma, delta, epsilon, and zeta chains and lacks kinase activity.
Adaptive immunity
The document summarizes key aspects of the adaptive immune system, including the roles of T lymphocytes and B lymphocytes. It discusses:
1) The two main types of lymphocytes are T lymphocytes and B lymphocytes. T lymphocytes mediate cell-mediated immunity while B lymphocytes mediate antibody-mediated or humoral immunity.
2) Helper T cells recognize antigens presented by antigen-presenting cells and activate other immune cells like B cells and cytotoxic T cells. Cytotoxic T cells directly kill infected cells.
3) B cells produce antibodies that target extracellular pathogens. Upon activation by helper T cells, B cells differentiate into plasma cells that secrete large amounts of antibodies, establishing antibody-mediated immunity.
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The document discusses the major histocompatibility complex (MHC) and its role in immune recognition. It notes that Gorer and Snell in the 1930s discovered that mouse skin grafts were rejected between mice of different blood groups, showing tissue recognition is based on genetics. They coined the term MHC to describe the genes controlling this tissue recognition. MHC molecules present peptides and are highly polymorphic within and between species, allowing an organism to distinguish self from non-self. The MHC in humans is called the HLA complex.
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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.
M H C
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.
Mhc
The MHC encodes antigen presenting molecules that display peptide fragments to T cells to initiate immune responses. It contains three regions - Class I MHC presents intracellular peptides to CD8+ T cells, Class II MHC presents extracellular peptides to CD4+ T cells, and Class III MHC encodes complement proteins. MHC molecules are highly polymorphic and individuals inherit multiple alleles from each parent. This polymorphism allows presentation of a wide range of peptides and enhances immune responses against pathogens. MHC matching is important for transplantation, as mismatch can lead to graft rejection through T cell recognition of foreign MHC.
Carbon cycle
Carbon is an essential element that cycles between the atmosphere, ocean, organisms, and geologic reservoirs as part of the carbon cycle. Photosynthesis incorporates carbon from the air and water into organic compounds, while respiration and decomposition release it back. Fossil fuels like coal and oil were formed from ancient plant and algae remains over millions of years. Burning fossil fuels returns carbon to the air, and limestone erosion also adds carbon back to the cycle through weathering. The carbon cycle continuously moves carbon between the biosphere and geosphere.
Structure of Ecosystems
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MHC.pptx
The Major Histocompatibility Complex (MHC) is a set of genes located on chromosome 6 that encode MHC molecules displayed on cell surfaces. MHC molecules control the immune response through recognition of self and non-self antigens. There are two main classes of MHC molecules - Class I molecules present intracellular peptides to CD8+ T cells, while Class II molecules present extracellular peptides internalized by antigen presenting cells to CD4+ T cells. MHC molecules play a crucial role in the immune system through antigen presentation and recognition.
MAJOR HISTOCOMPATIBILITY COMPLEX by Pranzly.ppt
The document discusses the major histocompatibility complex (MHC), which encodes MHC molecules that act as antigen presenting structures. MHC molecules are classified into three classes - MHC class I molecules present endogenous antigens to CD8+ T cells, MHC class II molecules present exogenous antigens to CD4+ T cells and are expressed on antigen presenting cells, and MHC class III molecules encode complement proteins. The document describes the structure, mechanism of antigen presentation, and functions of MHC class I and class II molecules.
L6.0 Immune recognition molecule (MHC,T cell receptor, T cell epitopes, T cel...
The document discusses immune recognition molecules, focusing on major histocompatibility complex (MHC), T-cell receptors, T-cell epitopes, T-cell markers, B-cell epitopes, and Toll-like receptors. It describes how MHC molecules present antigen peptides to T cells to initiate immune responses. MHC class I molecules present intracellular peptides to CD8+ T cells, while class II molecules present extracellular peptides to CD4+ T cells. MHC molecules bind peptides through their peptide-binding cleft in a polymorphic and promiscuous manner. Very few peptide-MHC complexes are needed to activate antigen-specific T cells.
Major Histocompatibility Complex
Some potential causes of the immune system attacking the self in autoimmune diseases include:
- Genetic predisposition - Genes coding for the variety of MHC molecules can influence susceptibility. A T cell's ability to respond is determined by MHC genotype. Differences in MHC alleles' ability to present autoantigens can play a role.
- Environmental triggers - Factors like infections, drugs, trauma, etc. may trigger autoimmunity in genetically susceptible individuals by molecular mimicry or other mechanisms.
- Loss of tolerance - Failure to eliminate self-reactive lymphocytes during development or maintain peripheral tolerance can allow self-reactivity.
- Hormonal factors - Many autoimmune diseases are more common in women and fluctuate with horm
MHC
This document provides a summary of a credit seminar on the major histocompatibility complex (MHC). The seminar covered the introduction, definition, history, classes of MHC, differences between MHC class I and II, and MHC in animals. MHC plays an important role in distinguishing self from non-self and antigen presentation. There are three classes of MHC - class I presents antigens to cytotoxic T cells, class II presents antigens to helper T cells, and class III encodes immune system proteins. MHC genes are highly polymorphic and influence disease resistance in various animal species.
Antigen processing and presentation. Antigen – Antibody Interaction.
This document discusses antigen processing and presentation and antigen-antibody interactions. It describes:
1) How antigens are processed intracellularly and presented on MHC class I and II molecules to activate CD8+ and CD4+ T cells, respectively.
2) The pathways of antigen processing for MHC class I, which presents endogenous antigens, and MHC class II, which presents exogenous antigens.
3) How antigen-antibody interactions are driven by non-covalent bonds and depend on factors like affinity, avidity, and valency. Antigen-antibody reactions can result in agglutination or precipitation.
Mhc.anu
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.
Major Histocompatibility Complex (MHC)
Major Histocompatibility Complex
Presented By-
Dr. Shubhi Mishra
Department of Life Science
Sardar Patel University Balaghat
MAJOR HISTOCOMPATIBILITY COMPLEX
MAJOR HISTOCOMPATIBILITY COMPLEXDr. Harisingh Gour Vishwavidyalaya (A Central Universuty), Sagar, MP
MHC A very important topic to the point of view for immunology here you will be able to learn about the detailed information of itMajor Histocompatibility Complex
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.
Antigen processing & presentation
1. Antigen processing and presentation involves degradation of antigens into peptides, association of peptides with MHC molecules, and display of peptide-MHC complexes on the cell surface for recognition by T cells.
2. There are two main pathways of antigen processing - exogenous antigens that enter the cell are processed through the endocytic pathway while endogenous antigens are processed through the cytosolic pathway.
3. In the cytosolic pathway, antigens are degraded by the proteasome and transported by TAP into the ER where they can bind to MHC class I molecules. In the endocytic pathway, exogenous antigens internalized into vesicles are degraded into peptides that bind MHC class II molecules.
A Short Note on MHC Molecules
The document provides information about MHC molecules. It discusses that MHC molecules are classified into two types - Class I and Class II. Class I molecules are expressed on all nucleated cells and present intracellularly derived peptides to CD8+ T cells. Class II molecules are only expressed on antigen presenting cells and present extracellularly derived peptides to CD4+ T cells. It describes the structure of Class I and Class II molecules and the pathways of antigen processing and loading of peptides onto MHC molecules. It also discusses T cell recognition of peptide-MHC complexes and the process of cross-presentation.
Antigen processing and presentation manu
This document discusses antigen processing and presentation pathways. It explains that antigens are processed into peptides which are then presented on the surface of antigen presenting cells bound to MHC molecules. There are two pathways: exogenous antigens taken up by cells are processed through the endocytic pathway and presented by MHC class II molecules. Endogenous antigens synthesized within cells use the cytosolic pathway and are presented by MHC class I molecules. Professional antigen presenting cells like dendritic cells, macrophages and B cells present antigens to activate T cells.
Rendon MHC presentation, A Brief Introduction.
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.
MHC and TCR
The document summarizes key aspects of major histocompatibility complex (MHC) molecules and T cell receptor (TCR) recognition. It discusses how MHC genes were found to be important in transplant rejection and immune responses. There are three classes of MHC molecules - Class I found on nucleated cells, Class II on antigen presenting cells, and Class III molecules like complement components. The TCR recognizes antigen peptides bound to MHC molecules. Both MHC and TCR are highly polymorphic and recognize antigens in a MHC-restricted manner.
Major histocompactibility complex
The major histocompatibility complex (MHC) is a collection of genes located on chromosome 6 in humans that encode MHC molecules. MHC molecules present peptide fragments on the cell surface to help the immune system identify infected or damaged cells. There are two main classes of MHC molecules: class I molecules present peptides from intracellular proteins on most nucleated cells to cytotoxic T cells, while class II molecules present peptides from extracellular proteins on antigen-presenting cells to helper T cells. MHC molecules play a key role in immune system functions like regulating T cell development and activating immune responses against pathogens.
IGNTU-eContent-392458762550-B.Sc-Biotechnology-4-Dr.PrashantKumarSingh-IMMUNO...
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.
principles-of-transplantation.ppt
The document discusses principles of transplantation, including goals of understanding HLA immunogenic response and T cell activation pathways. It describes types of grafts and immune responses to transplanted tissues. The roles of T cells, B cells, and antigen presenting cells in transplant rejection are explained. The document also summarizes MHC structure and function, antigen processing and presentation, and the three signal pathway of T cell activation and its significance in transplantation.
Pharm immuno7&8 cytokines r
1. The document discusses antigen presentation by MHC class I and II molecules and the roles of cytokines and cell-mediated immunity. MHC class I presents intracellular antigens to CD8+ T cells, while MHC class II presents extracellular antigens to CD4+ T cells.
2. Cytokines secreted by lymphocytes regulate immune cell activation, growth, and differentiation. They also mediate immune-related inflammation. T helper cells activate other immune cells and help induce antibody production.
3. Cytotoxic T cells kill infected cells presenting antigens from intracellular pathogens like viruses. Natural killer cells can also kill infected or abnormal cells through both MHC-dependent and independent mechanisms.
5. MHC.ppt
Major Histocompatibility Complex (MHC) molecules present peptide antigens to T cells and are highly polymorphic. MHC molecules are classified into three main classes - Class I molecules present intracellular peptides to CD8+ T cells, Class II present extracellular peptides to CD4+ T cells, and Class III genes encode complement proteins. MHC molecules have a peptide-binding groove that binds short peptides for presentation to T cells. MHC polymorphism generates a diverse repertoire of molecules that can present a wide variety of peptides and mount immune responses against pathogens.
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SIMILARITIES BETWEEN CLASS I AND CLASS II
- 1. Similarities between MHC class I and MHC class II Both are synthesized in rough endoplasmic reticulum Both are found on the surface of APC surface Both are encoded by genes in HLA locus In both class I and class II, expression of genes is co-dominant
- 2. Difference between MHC class I and MHC class II MHC class I MHC class II 1. Have 8-10 amino acids Have 13-18 amino acids 2. Peptide binding domain alpha1, alpha2 Peptide binding domain alpha1, beta1 3. Present antigen to CD 8 T- cells Present antigen to CD 4 T- cells 4. Found on all surfaces of nucleated cells Found on surface of APCs and activated T cells 5. Composed of one peptide encoded in HLA locus and beta 2 microglobullin Composed of two peptide encoded by HLA locus 6. Bind with endogenous antigen Bind with exogenous antigen 7. Has no invariant chain Has invariant chain
- 3. Cont… MHC class I MHC class II 8. After binding to CD 8 T cells, cytokines are produced that lead to the lysis of entire cell After binding to CD4 T cells it triggers B cell response which result in antibody formation
- 4. Special thanks • Prof. Mramba Nyindo-tutor at kcmu college • All BSc. Health laboratory science year two students(2016/17) at kcmu college. PREPARED BY PETER R. MASSAWE BSc HEALTH LABORATORY STUDENT at kcmu college year two 2016/17 massawepeter124@gmail.com