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20 Cards in this Set
- Front
- Back
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Ag Processing Pathways -- MHC II Synthesis
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1. MHC II protein synth in ER; invariant chain attaches to class II protein
2. Phagocytosis of foreign (exogenous) protein 3. Synthesis of viral proteins (petidases) cut proteins into peptides |
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MHC I vs MHC II
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MHC I:
- found on all nucleated cells - elicit only CMI - INTRACELLULAR pathogens: viruses, bacteria, cancer cells MHC II: - found only on APC - elicit CMI and HMI - EXTRACELLULAR pathogens - HMI: TH2 - B cells and ABs - CMI: TH1 and Tc/macrophages |
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2 signals for activation of Tc
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1. IL-2
2. TH2 cytokine to cause B cell prolif and differentiate |
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Adaptive Immune Response
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CMI and HMI
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What glycoprotein is expressed in TH1 and TH2?
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CD4
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What glycoprotein is expressed in Tc?
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CD8
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What glycoprotein is expressed in memory cells?
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CD4 and CD8
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What glycoprotein is expressed in regulatory (suppressor) cells?
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CD4
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What glycoprotein is expressed in NK cells?
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None
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What to cytotoxic Tc release?
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Cytotoxins and granules such as perforin - cause cell to lyse
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What do regulatory cells do?
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Suppress immune response, maintain tolerance to self Ags
Prevents auto-immune disease |
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What do NK cells?
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much like Tc, de-granulate and rel. cytotoxins
look for presence of MHC I and ABs bc have Fc receptor on cell surface |
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What to CD4 TH cells do?
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TH1: Helper cells, release cytokines that induce inflammation and activate macrophages containing intracellular bacteria and Tc
TH2: Release cytokines that help B cells make AB |
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How does body stop Tc from attacking itself?
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Positive and negative selection
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Positive Selection
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Tc are selected for ability to bind to MHC proteins
Those unable to bind to MHC eventually die Must bind to survive |
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Negative Selection
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Tc that interact with self Ags are deleted in thymus (90%)
Must only recognise foreign |
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Autoimmune Diseases
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overactive immune response of the body against substances and tissues normally present in the body = body attacks its own cells
Tc that recognises self Ags escapes deletion |
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Exs Autoimmune Diseases
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Type I Diabetes: can't recognise glucose in blood --> No insulin secretion
Lupus: chronic inflammatory disease Multiple sclerosis: myelin sheath destroyed Rheumatoid arthritis: conducts APs, no nodes of Ranvier, systematic inflammation, targets joints |
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How do TCRs on Tc and TH cells know to bind on MHCI and MHCII Ag complexes?
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different cellular differention CD mcls displayed on Tc and TH cell surfaces
Tc have CD8 that bind MHC I (intra) TH have CD4 that bind MHC II (extra) |
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What is the role of CD4 TH1 cell?
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help stabilize interaction between APC and Tc long enough for Tc to activate
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