9. Major Histocompatibility Complex (MHC) PDF

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Summary

IMMUNOLOGY SEROLOGY MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) large, consisting of several thousand kilobase pair of DNA on a single chromosome forms a group of genes that controls not only wide range of thissues but also the cellular interaction of immune cells, ...

Description

IMMUNOLOGY & SEROLOGY

MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) - large, multi-gene consisting of several thousand kilobase pair of DNA on a single chromosome - forms a group of closely-linked genes that controls not only wide range of thissues but also the cellular interaction of immune cells, the production of certain serum proteins & the production of some cytokines & enzymes - in human, it is referred as “Human Leukocyte Antigen” located on Chromosome #6 NATURE OF HLA:  Glycoprotein component of cell membranes  Present in all nucleated cells  Products of the genes of MHC ORGANIZATION OF HLA BASED ON THEIR CHEMICAL COMPOSITION

TRAITS UNDER CONTROL

CLASS I: A, B, C, E, F, G, H, X

- Transplantation antigens - Serologically detected membrane antigens - Cellular target antigens for cell-mediated Lympholysis

CLASS II: Dp, DW, DR, DM, DN, DO * TRANSPORTER ASSOCIATED WITH ANTIGEN (TAP) - transports Ag from Cytosol to Endoplasmic Reticulum * LARGE MULTI-FUNCTIONAL PROTEASE (LMP) - stimulated production of Protease

- Region I Leukocyte Antigen - T-cell & B-cell production - Immune response - Mixed Leukocyte reaction - Graft vs. Host reaction - Tumor virus susceptibility - Peptide transport - Generation of peptides from cytosolic proteins

CLASS III: Complement components, Cytochrome p450, 21-Hydroxylases, & TNF

- Serum protein molecule - Complement levels - Cytokines& Enzymes

PROPERTIES OF MHC MOLECULES CLASS I Genetic tool

HLA- A, B, C

Chain structure

α chain + β2 microglobulin

CLASS II HLA SB (DP), DC (DQ), DR α chain + β chain APC (macrophage, dendritic cells, Langerhan cells, T-cells & B-cells, Endothelial, Epithelial, & Stromal cells) T-helper cells (CD4+ T-cells)

Cell distribution

All nucleated cells Except: Neural cells, Sperm cells, & liver cells

Present antigen

T-cytotoxic cells (CD8+ T-cells)

Source of peptide fragments

Proteins made in the Cytosol

Endocytosed plasma membrane & Extracellular proteins

Polymorphic domains

α1 + α2

α1 + β2

* The highly polymorphic genes within the MHC gene segment of DNA code for a wide range of cell surface structure that T-cells must recognize in association with foreign antigen for a successful response

MHC RESTRICTION / MHC RESTRICTED RECOGNITION: JOYCE ANN S. MAGSAKAY

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BS MEDICAL LABORATORY SCIENCE

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OLFU VALENZUELA

IMMUNOLOGY & SEROLOGY

MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) - the process whereby the mHC control interaction between cells - it involves the recognition of foreign antigen in association with Class I or Class II molecules REACTIONS SONCIDERED AS MHC RESTRICTION: 1. Antigen Presentation 2. T-cell & B-cell cooperation 3. Cytotoxic T-cell interaction with target cells APPLICATION OF HLA TYPING/MATCHING: 1. Organ transplantation 2. Paternity testing 3. Studies of Racial Ancestry & Migration 4. for Diagnostic & Genetic counseling 5. Forensic medicine & Anthropology 6. Basic research in Immunology METHODS FOR DETECTING HLA ANTIGENS: (HISTOCOMPATIBILITY TESTING) TISSUE TYPING 1. Serological Approach (Lymphocyte Microtoxicity Method: for determination of Class I antigens) 2. Cellular Approach (Mixed Lymphocyte Reaction: for determination of Class II antigens) 3. Molecular Aprroach (Polymerase Chain Reaction (PCR) & Restriction Fragment Length Polymorphism (RFLP)

JOYCE ANN S. MAGSAKAY

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BS MEDICAL LABORATORY SCIENCE

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OLFU VALENZUELA...