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22 Cards in this Set
- Front
- Back
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What is the distinguishing features of gamma/delta T-cells? |
- relatively small percentage of Tcells - very few express CD4 or CD8 - Not MHC restricted - "primitive" cell type that is found in mucosal epithelium - thought to recognize non-protein antigenic determinants -don't mature in the thymus |
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What receptor on the T cell recognizes the MHC molecules? -what part transduces the signal? |
- TCR recognizes the peptide bound to MHC - The TCR/CD3 complex is responsible for transducing the signal into the cell |
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What type of MHC is recognized by CD4 |
MHC 2 |
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What type of MHC is recognized by CD8 |
MHC 1 |
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What are the RAG 1/2 enzymes responsible for? |
Somatic Hypermutation/recombination |
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What is the TdT enzyme responsible for? |
junctional diversity (this is true in T cells as well as B cells) -it adds N nucleotides at the junctions between gene rearranging segments of TCR |
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What does CD45 do? |
Accessory molecule; a transmembrane protein tyrosine phosphatase that is involved in T cell activation. |
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What does CD28 do? |
Binds to B7 to deliver a required co-stimulation |
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What does CTLA-4 do? |
present on some T cells and when it engages with the B7 molecule, it causes dampening of T cell activation by causing secretion of anti-inflammatory cytokines |
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What does CD5 do? |
Present on all T cells; binds to B cells and promotes activation |
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What does Fas Ligand do? |
binds to Fas expressed on a target cell and induces apoptosis of the target cell. |
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What does lymphocyte function antigen (LFA-1) do? |
interacts with intracellular adhesion molecules (ICAM-1/2/3) on target cells. |
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What does CD2 do? |
binds to LFA-3 on target cells and promotes cell-to-cell adhesion and T cell activation |
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What does VLA-4 and VLA-5 do?` |
Adhesion molecules. bind to fibronectin on the target cells and enhances the interaction between the T cell and target cell. |
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What type of cells are found in the thymic cortex? |
immature T cells and scattered macrophages |
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What type of cells are found in the thymic medulla? |
more mature thymocytes, dendritic cells, and macrophages |
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Where does positive selection for T cells occur? |
Thymic cortex |
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Where does negative selection for T cells occur? |
Thymic Medulla |
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What are tingible body macrophages? |
cortical macrophages that phagocytose apoptotic thymocytes |
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Where does the selection for single positive T cells happen? |
cortico-medullary junction |
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What is negative selection? |
T cells that bind too tightly to self peptide:MHC complexes are induced to undergo apoptosis |
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Which parts of the TCR correspond to the Ig molecule |
alpha chain of TCR = light chain Ig genes beta chain of TCR = heavy chain |
