Vorlesung Antigenpräsentation 27-04-16 Sandra Nitsche ...€¦ ·
Transcript of Vorlesung Antigenpräsentation 27-04-16 Sandra Nitsche ...€¦ ·
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Cells are based of different compartments
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Antigen presentation for what reason?
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Activation of T-Cells
Proliferation is intracellular located and are not accessible for antibodies
Virus and somebacteria andparasites
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Which cells are necessary for antigen presentation?
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Key player of the adaptive immunity
T-Cells(out of the thymus)
T-cells are necessary for the control of intracellularpathogens and are responsible for the activation of B-Cellsagainst most antigens (exception: Superantigens)
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Which cells are necessary for antigen presentation?
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Cell based reaction between T-Lymphocyts and antigen presenting cells (cells which recognize the antigen, which is presented on the T-cells)
In both cases recognize T-cells the target cells based on peptide fragments of different proteins (f.e. virus- or bacterial components).
T-helper-cells (CD4+-T-cells)Cytotoxic cells (CD8+-T-cells)
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HLA or MHC
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„Haupthistokompatibilitätskomplex (HLA)“or
Majorhistocompatibility complex (MHC)
Are membrane bound glycoproteins, which present peptides as antigen to the T-cell.
MHC-Gens are important for the compatibility of tissue transplants, because many tight-knit polymorph Gens are responsible for the Histocompatibility.
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MHCI and MHCII
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T-cells recognize peptide fragments, which are from an extrinsic antigen, only if they are bound to an MHC-molecule.
Es gibt zwei Klassen von MHC-Molekülen:
MHC I-moleculeMHC II-molecule
Important differenses: -> Home of the peptide, which „capture“ the MHC-molecules and transport them to the cell membrane.
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MHC I molecule expressed by nucleolare cellsMHC II molecule only expressend from antigen-presenting cells
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Overview on antigen-presenting cells and their function
Pathogens and their products are located in the cytoplasm or in cell vesicles.
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Characterisation of antigen-presenting molecules MHC
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1.Step: Antigen uptake- and processing
MHC I molecules are out of the cytosol
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2. Step: Stimulation of T-cells with antigen-presenting cells
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Molecular structure of MHC I
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Conserved amino acids coordinate the binding of peptides to MHCI
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MHC I-T-cell complex
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MHC II molecules, which are presented on the surface of APC are from extracellular antigen
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Molecular structure of MHC II
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Binding of peptides to MHC II
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MHC II-T-Zellkomplex
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MHC and the peptid have to be bound specific from the T-cells for activation
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auf Chromosom 6
auf Chromosom 17
Genome organization of MHC by human and mice
Polygenie
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Polymorphism and polygene improved the MHC-Variability
Codominate Expressionvon MHC Allelen!
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Variability of allele is concentrated on the peptide binding region of MHC
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One specific MHC molecule is able to bind many different peptides
Ala A
Cys C
Asp D
Glu E
Phe F
Gly G
His HIle ILys KLeu LMet MAsn N
Pro P
Gln Q
Arg R
Ser SThr TVal VTrp WTyr Y
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Variability of MHC Allele in Humans
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Rejection of organs: different situations are possible!
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Strategies of pathogens to invade the immune system by blocking the antigen presentation
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Presentation of MHC I with peptides
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Transport of MHC I peptide complex to the cell surface
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cellular synthesis of MHC II molecules
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Presentation of MHC II with peptides
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Cross-Presentation
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Summary