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Immunology

03.05.2017, Ruhr-Universität Bochum

Marcus Peters, marcus.peters@rub.de

Antigenpresentation

Important Abbreviations: MHC --- Major Histocompatibility Complex HLA --- Human Leucocyte Antigen

MHC I = HLA-A, HLA-B, HLA-V MHC II = Alpha-chain Beta-chain HLA-DMA HLA-DMB HLA-DOA HLA-DOB HLA-DPA1 HLA-DPB1 HLA-DQA1, HLA-DQA2 HLA-DQB1, HLA-DQB2 HLA-DRA HLA-DRB1, HLA-DRB3, HLA-DRB4, HLA-DRB5

Cells consist of different compartiments

MHC I molecules are expressed by every nucleated cell MHC II molecules are expressed by antigen presenting cells only

Overview of antigen presenting cells and their functions

Characterization of the antigen presenting molecules MHC

On MHC I molecules are displayed that are derived from

the cytosol

CD8 exprimierende zytotoxische T-Zelle

Loading of MHC I with peptides

Transportation of the MHC I peptide complex to the cell surface

ERAP=endoplasmic reticulum aminopeptidase UGT=UDP-glucuronosyltransferase TAP= Transporter associated with antigen processing

Molecular structure of MHC I

Conserved amino acids coordinate the binding of peptides to MHC I

Coordination of the MHC1 binding peptide

MHCI/Peptid Komplex in Interaktion mit dem T-Zell-Rezeptor

Antigen präsentierende Zelle

Zytotoxische T-Zelle

On MHC II molecules are displayed that are derived from

the extracellular medium

CD4 exprimierende T-Helfer-Zelle

Loading of MHC II with peptides

Molecular structure of MHC II

Binding of peptides to MHC II

T-Helfer-Zelle

Antigen präsentierende Zelle

MHCII/Peptid Komplex in Interaktion mit dem T-Zell-Rezeptor

Both the MHC and the appropriate antigenic peptide must be Recognized by the T cell

Genomic organization of the MHC on chromosome no. 6

Polygenie

Polymorphism and Polygenism increase the variability of MHC molecules

Codominat expression of MHC alleles!

Allelic variabilty is concentrated on the peptide binding region of MHC

One specific MHC molecule is able to bind several different peptides

Enumeration of the known diversity of MHC alleles in human

Strategies used by pathogens to evade the immune response by affecting antigen presentation

Different situations may lead to the rejection of a non-compatible transplant