Cell Mediated Immunity (Waziry) Flashcards
what type of immunity is required to defeat intracellular pathogens which are hidden inside cells?
Cell mediated immunity
The core of CMI are:
helper T cells (CD4+) and cytotoxic T cells (CD8+)
what activates Th1 cells?
IL-12 and IFN-g
what activates Th2 cells?
IL-4
what activates Th17 cells?
IL-6, IL-23, TGF-B
What 2 signals are needed in T cell priming?
1) antigen presentation on MHC that binds to TCR
2) co-stimulation via CD28 (on T cells) binds to B7 on APC –> immune synapse–> leads to activation of T cell
What do Th1 cells express and what do they produce?
express T-bet and STAT4; produce IFN-g and IL-2
the most potent macrophage-activating cytokine known is..?
IFN–g
what does IL-2 do?
stimulates proliferation and differentiation of NK cells & activated T cells
DCs can present ags in both MHC I and MHC II: DCs phagocytose infected host cells and pathogenic Ags are moved into the cytosol for MHC I. what is this known as?
cross presentation or cross-priming
What do Th2 cells express?
Express GATA3 and STAT6
What do Th2 cells produce? what do they target?
IL-4,5,6; target eosinophils (IL-5)
(T/F) Th2 cells can inhibit Th1 cells
TRUE
Th2 cells also function to stimulate isotype switching to IgE to B cells via:
IL-4 and IL-13
Th17 cells express what and produce what?
ROR(gamma)t; produces Il-17 and Il-22 in order to promote inflammation
Main fxn of Th17 cells?
recruitment of neutrophils & monocytes to site of infection
T follicular helper cells express what?
express Bcl-6
What do T follicular helper cells produce?
Produce IL-21 and ICOS–> assists in activation of B cells
Treg cells express what and what is their purpose?
express Foxp3; helps suppress immune response by producing TGF-B, IL-10, and IL-35
what markers are present on regulatory T cells?
CTLA-4 and LAG-3
cytotoxic T cells express what? what do they produce?
express RUNX3; produce perforin, granzymes, FasL, etc
what do cytotoxic T cells secrete in order to increase expression of MHC genes?
IFN-g and macrophages
what do cytotoxic T cells secrete in order to activate macrophages & enhance their phagocytic ability?
TNF-B
describe CTL fas-fasL killing?
- Fas is a surface protein present on some cells; FasL is a surface protein on CTLs and Th1 cells (not on naive T cells)
- Presentation of foreigner makes Tc become activated→ Tc cell interacts w/ FAS on infected cell→ signal from Tc makes the infected cell commit suicide via activation of caspases
- If the infected cell needs more help dying, T cell can release granzymes and perforin (direct & focused so no damage to other cells)
clonal deletion?
apoptosis of clonal T cells as an immune response comes to a close
Tc cells can express Fas and have it bind to its own FasL. what is this known as?
Activation Induced Cell Death (AICD)
how do we clean up dead evidence?
macrophages! they look for externalized P-tidylserine (flipped bodies)
