Term
| What does a DTH skin test measure? |
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Definition
-Delayed type hypersensitivity test
-Measures TH1 cell activity |
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Term
| How does a CTL recognize a cell for destruction? How about a NK cell? Which types of viruses are each method better at catching? What type of virus (give name) can avoid both, how, and what eventually catches it? |
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Definition
-CTL respond to non-self antigens on MHC I; this is better for catching the fast replicating type viruses
-NK cells respond to a lack of MHC I molecules on the surface; this is best for catching the slower viruses that down regulate MHC expression
-Viruses that use decoy MHC proteins, such as cytomegalovirus (CMV), are tricky because they aren't recognized at all by CTLs, but are recognized by NK cells (who don't care that they are a bit different)
-Eventually antibodies are made against the decoy MHCs (ADCC initiated) |
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Term
| What two things stimulate CTL? What third thing stimulates them indirectly? |
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Definition
-Non-self MHC 1
-IL-2; causes them to proliferate more
-INF-γ is the third thing; works by increasing MHC 1 expression |
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Term
| What methods do CTLs use to kill (3)? |
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Definition
-Perforins and granzymes; makes pore & serine proteases go in and activate caspases
-Cytokines (IFN-γ, & TNFs); induce apoptosis
-FasL; binds to Fas and caspaces are activated |
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Term
| What molecules are involved in CTL binding? |
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Definition
| -TCR, CD8, & LFA-1 (to I-CAM) |
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Term
| What is another name for the MHC proteins in humans? |
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Definition
-HLA molecules (human leukocyte antigen)
-This term is used especially in reference to rejection of transplanted organs (caused by HLA polymorphism) |
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Term
| What cells are the only innate lymphocytes? |
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Definition
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Term
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Definition
-Same as CTLs, but without the FasL; perforin/granzyme combo & cytokines (TNF-β, INF-γ)
-They recognize missing MHC I proteins
-Can also do the whole ADCC thing |
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Term
| What two receptors do NK cells have? |
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Definition
-They have activation receptors that bind to lectin
-They also have inhibitory receptors that bind MHC I (the more important mech of the two) |
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Term
| What are the markers for NK cells again? |
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Definition
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Term
| What stimulates NK cells? (3) |
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Definition
-IFN-α, IFN-β, and IL-12
-Remember, IL-12 also calls for TH1 cells (produced by macrophages) |
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Term
| Name the four mechanisms of cell-mediated cytotoxicity? |
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Definition
-Macrophages
-CTL
-NK cells
-ADCC |
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Term
| What is ADCC and how does it work? What specific molecule is recognized and what is one exception to this? |
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Definition
-Antibody-dependant cell-mediated cytotoxicity
-Pretty much all the cytotoxic cells (NK, mac, mono, neu, & eosinophils) have Fc receptors and can kill opsonized cells
-IgG is the only ADCC stimulating Ig (the opsonizing Ab), the exception is that IgE can also be recognized in the case of parasitic worm infection |
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Term
| What are the main stimulating molecules for macrophages, CTLs, and NK cells? What are their markers? What do they use to kill? |
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Definition
-Mac; IFN-γ
-CTL; IL-2
-NK; IFN-α, β, and IL-12
-Mac; CD14
-CTL; CD3, CD8
-NK; CD16, CD56
-Mac; TNF-α, phagocytosis, granule release
-CTL; Perforin & granzyme, cytokines(TNF-β, INF-γ), FasL
-NK; Perforin & granzyme, cytokines(TNF-β, INF-γ) |
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Term
| Why would we use cell-mediated rather than humoral? |
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Definition
| -For intracellular pathogens |
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