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9 Cards in this Set
- Front
- Back
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The MHC protein peptide complex on the surface of the antigen presenting cells bind to appropriate T cells. TRUE/FALSE
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TRUE.Receptors on the T cells must recognize a very wide variety of complexes.
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What are most of the T cell receptors composed of?
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Two polypeptide units designated alpha and beta. They form heterodimers that recognize the MHC proteins and the antigen fragments with which they are combined. These are referred to as alpha-beta T cells.
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About 10% of circulating T cells have 2 different polypeptides designated gamma(y) and delta(8) in their receptors and they are called y8 T cells. TRUE/FALSE
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TRUE.
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Where are many of these gamma-delta T cells found?
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They are prominent in the mucosa of the GI tract, and may form a link between the innate and acquired immune system by way of cytokines they secrete.
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Where is CD8 found?
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These occur on the surface of cytotoxic T cells that bind MHC-1 proteins, and CD4 occurs on the surface of helper T cells that bind MHC-11 proteins.
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What do the CD8 and CD4 proteins do?
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They facilitate the binding of the MHC proteins to the T cell receptors and they also foster lymphocyte development.
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What is the difference between the CD8 and CD4 molecules?
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The CD8 cytotoxic T cells kill their targets directly, whereas the activated CD4 helper T cells secrete cytokines that activate other lymphocytes.
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What is the immunologic synapse?
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The T cells receptors are surrounded by adhesion molecules and proteins that bind to complimentary proteins in the APC when the two cells transiently join to form the immunologic synapse, that permits T cell activation to occur.
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Is more than 1 signal necessary to cause activation of T cells?
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Yes. Two signals are necessary to produce activation. One is produced by the binding of the digested antigen to the T cell receptor. The other is produced by the joining of the surrounding proteins in the synapse. Both signals must be created for activation.
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