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Chapter 14- Cell-mediated responses. Where we’re going with this chapter: Understanding “effector” cells- and how they are different from naïve cells. The CTL killing process- apoptosis. NK cells ADCC How we test these things. Die, you horrible traitor!. AAAAGH!.
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Chapter 14- Cell-mediated responses • Where we’re going with this chapter: • Understanding “effector” cells- and how they are different from naïve cells. • The CTL killing process- apoptosis. • NK cells • ADCC • How we test these things
Die, you horrible traitor! AAAAGH!
Think of “effector” cells as the ones doing the job- the “non-activated” effector cells would be memory cells, waiting to be activated; or a cell that has stopped responding, but has been restimulated. This form activates lyk and fyn better!
The CTL response- an older version, but useful Note that it’s not necessarily the same Ag stimulating the Th1 as stimulating the Tc cell- the Tc cell just needs the IL2- but see next slide! The activation step makes it responsive to IL2
“Licensing” of an APC • Dendritic cells appear to serve as “gatekeepers”- making sure that we’re not activating CTL’s improperly- perhaps against self-ag’s. The APC is “licensed” to present to a CTL-P, after being bound and stimulated by a Th1 cell.
This might be a virally-infected dendritic cell that’s also engulfed the same virus- so it’s doing both class I and class II ag presentation. Or, it get’s licensed by having its TLR’s activated.
Key point- they’re NOT in the lymph nodes- out finding/killing infected cells!
The gory details on killing (if it makes you feel better, killer T cells don’t actually kill cells; they persuade them to commit suicide)
Two pathways- granzymes and FAS Granzymes and FAS both work- alternate routes to the same effect
Once we generate the CTL’s we then use them in a killing assay
Cute, but sad, mice w/o an adaptive immune system, surviving on their NK’s!
How we think NK’s kill First, they kill like CTL’s kill- granzymes, Fas ligand, etc. The Q is – how do they pick their victims (er, targets)?
ADCC • Antibody-dependent cell-mediated cytotoxicity • Lots of different cells can do it- • A non-specific cell kills specifically due since the ab is specific. • Hydrolytic and granzymes released- probably locally.
Killing/activation assays We’ve actually done these before, but that’s OK! If Kuby does it twice, WE can do it twice!
This would be an MHC difference response, vs. one to a specific antigen that was used to show MHC restriction.
Specific, MHC restricted response Allogeneic response
Things to know from Ch 14 • What’s an effector cell? • Activation/proliferation of Tc cells, differentiation into CTLs. • Killing- FAS, FAS ligand, perforins, granzymes, caspases, mitochondria • NK’s- when do they respond, how do they kill • ADCC- cells involved, Fc receptor • Assays for proliferation and killing.