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21 Cards in this Set

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What part of the thymus does positive selection occur? negative selection
- cortex
- paracortico-medullary junction
What are the 3 kinds of intracellular microbes combated by cell-mediated immunity?
1) microbes within cytoplasm
2) microbes that survive within phagolysosomes
3) microbes within nonphagocytic cells
What are the phases of T cell responses to Ag?
- recognition
- activation
- clonal expansion
- differentiation
- effector function
What are the coreceptor, co-stimulators, and adhesion molecules important in T cell activation? what do they do?
- co-receptors: CD4/8 (signal transduction)
- CD3 (TCR complex for signal transduction)
- co-stimulation (CD28 for signal transduction)
- Adhesion (LFA-1)
What are superantigens?
- special class of Ags that activate multiple T cell clones by stapling together MHC II to TCR beta chains
- Cause Activation of many T cells to produce excessive Ag release that causes disease (activates without Ag)
- binds to the VBeta region
Activated APCs express what co-stimulators to cause activation of the T cell?
- B7 to bind to the CD28 on T cell
- Cytokines (IL-12) to activate T cell
What is the immune synapse?
- Receptors and ligands cluster around Ag recognition sites
Where are ITAMs located and what are they for?
- near the base of the epsilon chain
- phosphorylated which creates a signaling cascade to change a T cell to an effector T cell
What is the order of the molecules that cause the differentiation and proliferation of the T cell?
- transcription factors: c-Fos
- Membrane Effectors: CD40 ligand and Fas ligand
- Cytokines: IL-2/4, IFN-y
What does Il-2 do and what releases it?
proliferation/differentiation of effector/regulatory T cells
- CD4/8
What is the action and source of IL-4
- B cell switching to IgE
- CD4 or mast cells
What is the action and source of IL-5
- Activation of eosinophils
- CD4 or mast cells
What is the action/source of IFN-y?
- macrophage activation
- CD4/CD8 and NK cells
What is the action/source of TGF-beta?
- T cell inhibition and differentiation of T regulatory cells
- CD4 regulatory T cells
What do CD8 T cells require for activation if they recognize an Ag on an APC?
- help of a CD4 T cell
OR
- Costimulators on DC
What cytokine induces clonal expansion?
- IL-2
How does IL-2 induce clonal expansion?
- changes the IL-2 receptor from low to high affinity
What scenarios induce TH1 formation? by what cytokine?
- Innate, high phagocytic immunity (viral or high Ag concentration)
- IFN-y or IL-12 activates T-bet to produce TH1
What scenarios induce TH2 formation? by what cytokine?
- Helminth infection, allergen, low Ag concentration
- IL4 activates GATA-3, induces TH2 production
What are the functions of TH1?
- IFN-y causes macrophage activation; increased MHC-1 expression on APC;CD8 T cell activation; B cell complement binding/opsonization
What are the functions of TH2?
- IL-4 induces B cell neutralization by IgG and Mast cell degranulation by IgE
- IL-4/13 induces macrophage repair
- IL-4 activates eosinophils