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20 Cards in this Set
- Front
- Back
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Give the general structure of a TCR
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The TCR resembles the Fab portion of an Ig...It has an alpha and beta chain, each with a variable and constant region and a short cytoplasmic tail.
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What helices make up the MHC class I binding groove. The MHC class II Binding groove?
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MHC type one has alpha 1 and alpha 2 helices and a beta sheet as the floor. Type II has Alpha 1 and Beta 1 helices, and a beta sheet floor.
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What variable region genes make up the following chains of the TCR? Alpha, beta, gamma, and delta.
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Alpha and Gamma = VJ, Beta and Delta = VDJ
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What protein is required for VDJ rearrangement of T cells and B cells. What condition ensues if you do not have this protein?
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RAG 1 and RAG 2. SCID
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What proteins transmit the receptor signal of the TCR?
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gamma, delta, epsilon (CD3) and the zeta chains.
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If a cell is CD3+, what kind of cell do you have. How could you further distinguish these cells?
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CD3+ means you have a T cell. You could then screen for CD4 and CD8 to see if you have a Th or a Tc
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What are the two classes of TCR?
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AlphaBeta and GammaDelta
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After alpha chain rearrangement on chromosome 14 for TCR, what important event ensues?
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Deletion of the gamma chain locus on Chromosome 7
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What happens when a CD4+ Tcell comes in contact with an Ag presenting B cell?
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It secretes cytokines that cause the B cell to differentiate into an antibody secreting plasma cell.
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What happens when a CD4+ T cell comes in contact with a macrophage?
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It secretes cytokines that increase the microbicidal power of the macrophage and its secretion of inflammatory cytokines.
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What happens to a virus infected cell when it comes in contact with a CD8+ t cell?
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It kills it!
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Give the structure of MHC I and MHC II molecules.
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MHC I has 1 MHC encoded polypeptide (alpha 1, 2, and 3 subunits) and a B2 microglobulin. MHC II has 2 MHC encoded polypeptides (alpha 1 and 2 subunit, and beta 1 and 2 subunit).
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What cells is Class I MHC found on? Class II?
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MHC Class I is found on all nucleated cell. MHC Class two is much more restricted to just some Immune cells.
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What type of Ag does class II MHC bind? Class I?
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MHC Class II binds Exogenous Ag. MHC I binds intracellular Ag.
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Where in the cell does Class I MHC bind intracellular Ag? What molecules stabilize it to this structure?
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It waits for the Ag on the ER and is stabilized by beta 2 microglobulin and calnexin.
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What is ERAP and what does it do?
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Endoplasmic Reticulum Aminopeptidase trims intracellular Ags to 8-10 AAs longs so they fit in the groove of MHC I molecules in the ER
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Explain how exogenous Ags are presented by MHC II molecules.
Include: Site of MHC II Synthesis, clip, HLA-DM, invariant chain. |
MHC II's binding site is blocked by invariant chain in the ER. The molecule is then surrounded in a vessicle and leaves the ER. Invariant chain is cleaved leaving a clip bound fragment that prevents peptides from binding the MHC II ag site. When this vessicle binds with an endocytosed vessicle containing Ag, Clip is removed from the Ag binding site via HLA-DM, allowing ag to bind.
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What HLA loci code for MHC I? MHC II?
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HLA A, B, C code for MHC I, HLA DP, DQ, DR cod for MHC II
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Where are polymorphisms in HLA found in the peptide binding groove of MHC I molecules? MHC II?
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on the whole groove of type I, only on the beta chain of type II.
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Why must you match HLA types for organ transplants?
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B/c the MHC molecules may have polymorphisms in the binding groove which the host immune system may recognize as foreign!
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