BIOL 2050U Lecture Notes - Thymus, Ctla-4, Glycoprotein
Document Summary
Cd8+ cells respond to mhc class i indicates viral infection activation causes diffentiation into cytotoxic t cells. Cd4+ cells respond to mhc class ii indicates microbial infection activation causes differentiation into th1 or th2 cells. T cell costimulation signal 1 = antigen-mhc signal 2 = antigen independent costimulatory signal (b7) **ensures that only apc"s can cause t-cell differentiation** Dc"s most important activator of t-cells; presents viral antigens. B cells present bacterial and viral antigens. Initial encounter with apc"s signal 1 occurs in lymph nodes, peyer"s patches, spleen: t-cells diapedese through the endothelial walls (icam mediated, upon apc encounter, binding is first antigen independent. Cd2 (t cell) and lfa-3 (apc: antigen-dependent binding involves cd4/cd8 and tcr to mhc on apc mediated by itam, found within the invariant chain of tcr (cytoplasmic cd3 complex) Sh2 binding domain is exposed that binds zap-70 (protein kinase) (lck phos. Lat tyrosine kinase cascades activated: cascade 1: phospholipase c (plc) leaves pip2 to ip3 and dag.
