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21 Cards in this Set
- Front
- Back
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T-Cell Receptor
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-have alpha and beta chains which are the same side and bonded by disulfide bonds
-only ONE antigen binding site -have variable and constant region also |
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T-h Cell
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-helper T cells
-CD4 surface molecules -bind to MHC2 on APC cells with exogenous antigens from phagolysosome -secrete cytokines -4& H look the same |
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T-c Cell
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-CD8 surface molecules
-bind to MHC 1 on cells with endogenous antigens from the cytoplasm -secrete perforins |
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"first signal" in Th cells
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-TCR binding to MHC2 and antigen
-CD4 recognizes the MHC2 |
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"first signal" in T c cells
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-TCR binding to MHC1 and antigen
-CD8 binding to MHC1 |
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"second signal" in Th Cells
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-CD28 binds to the costimulatory molecules B7 or CD80
-the costimulatory molecule was produced by the APC binding of PAMP to TLR |
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"second signal" in Tc cells
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-CD28 binding to B7 of APC or binding of the cytokine IL-2 from the activated nearby Th cells
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Co-stimulatory peptide B7 (CD80)
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produced by the APC when PRR i.e TLR recognizes a PAMP
-second signal for T cells |
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Interleukin 2
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Cytokine released by nearby Th cells after being activated which can act as the second signal for Tc cell activation
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Naive T cell
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T cell that has not yet encountered an antigen
-needs 2 signals to be activated -if only 1 signal is recieved->becomes anergic |
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Effector T cell
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T cell that receives 2 signals and is activated
-releases perforins and granzymes to induce apoptosis if Tc cell -release cytokines if Th cell |
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Interleukin 10
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-opposite effect of IL-2
-reduce the expression of stimulatory cytokines from Th cells -important in the gut, lack of it contributes to Crohn's disease -produced by T reg cells |
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Autostimulatory Cytokines
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Cause the Th cell to proliferate- clonal selection
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T-regulatory cells
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-produce IL-10
-reduce the interaction of dendritic cells with Tc cells -has surface molecule CTLA-4 (CD152) which digests B7/CD80 on phagocytes so the T cells will not have a second stimulation and T cells become anergic |
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T-memory cells
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-long lived
-reactived just like memory B cells to produce a better response against second exposure, no need for B7/CD28 signal |
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Clonal Deletion
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-if T cells recognize self cells they are clonally deleted
-occurs in the Thymus in the throat -95% of T cells are selected against |
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Positive Selection
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-T cells are too weakly attached to MHC 1 in the thymus
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Negative Selection
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-T cells bind too tightly to the thymus because of self antigen and are never released into the circulation
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Natural Killer Cells
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-do not need to be stimulated to kill, therefore natural
-bind to vaccenic acid (unique fatty acid in glycolipids) -bind to stress sensor from any cell -release cytotoxins to kills attached cell |
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ADCC
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When natural killer cells bind to Fc part of antibody whose Fab parts are bound to a bacterium
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Cancel kill signal
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-MHC1 causes kill signal to be cancelled
-Cancer and virus infected cells often down regulate MHC1 or up regulate stress signals to cancel kill signal |
