#2 - Life of a T Cell: Mobilizing the Troops Flashcards
what self-peptide target of a T cell is the cause of MS?
myelin basic protein (MBP)
what does the ‘i’ in iNK stand for?
invariant
what CD4 count is associated with HIV (for the 12-18 age group)
<400
approximately what percentage of the total lymphocytes are T cells, in the spleen
20%
what are the three signals for T Cell activation?
Signal 1 is through the TCR
Signal 2 is via costimulation (from APC) via CD28 or ICOS
Signal 3 is a cytokine
where does T cell activation occur?
in a secondary lymphoid organ
name four of the adhesion molecules that bring APC’s and T cells together
VCAM, LFA-1, VLA-4, CD2, ICAM-1
B cell question: what happens in the germinal centers?
b cell activation, somatic hyperstimulation and class switch recombination
about how many HLA molecules are likely to express foreign peptides?
3-5 (out of 50,000-100,000)
how do these few HLA’s produce a response big enough to activate the T cell?
First, the TCRs rearrange the membrane of both the T cell and the APC to bring all the activated TCR’s together; this produces a site called the immunological synapse
Second, the TCRs internalize, replace themselves and recycle to continuously use the HLA
what is the first step of the TCR activation pathway?
tyrosine kinase activation that phosphorylates ITAM (ITAM - immunoreceptor tyrosine activation motif)
what’s the second step of the TCR activation pathway?
phosphorylation of ZAP-70/Syk (this is via Src PTK, but that’s not on the test)
what’s the third step of the TCR activation pathway?
activation of calcineurin, which increases intracellular Ca levels
what’s the fourth and final step of the TCR activation pathway?
activation of NFAT, NFkB and MAPK transcription factors (increase mRNA stability)
what is the mechanism of action for the transplant enabling drug, cyclosporin?
inhibition of calcineurin, which inhibits the T cell activation pathway
