Flashcards in Immunology Lecture 9. Deck (18):
non-responsiveness to antigen
antigen-presenting cells (APCs)
specialized cells that present antigens. main APCs for naive T cells are dendritic cells, macrophages, and B cells
serine proteases present in cytotoxic T cells that are involved in inducing apoptosis in the target cells
produced by activated naive T cells (autocrine response)- essential for further proliferation and differentiation
hematopoietic growth factor secreted by stromal cells in the bone marrow and thymus - important for development, survival, and homeostasis
protein that polymerizes to form membrane pores that are important in the killing mechanism of cell-mediated cytotoxicity
What is the order of events in T cell immunity?
recognition of antigen, activation of T cell, clonal expansion, differentiation, effector response (functions), decline, memory cells
How long do T cells stay in circulation?
until they recognize antigen on their receptor
What does it take to activate a T cell?
antigen recognition and costimulatory signal (B7/CD28)
What receptor is unregulated during an infection?
B7 on antigen presenting cells
TH1: cytokines that induce and function
IL-12 and IFN-y - function = activate macrophage
TH2: cytokines that induce and function
IL4 - activate cellular and antibody effect to parasites
costimulatory for activation of B cells OR activation of activated macrophages (with IFN-y)
What determines if a CD4 cell differentiates into a TH1 or TH2?
cytokine exposure after activation
fast killing (can be resynthesized and induce apoptosis)
How do T cells get turned off?
1. CTLA-4 (inhibitory receptor for B7 - higher affinity than CD28) 2. elimination of antigen/stimuli 3. T regulatory cells 4. killing of T cells with only memory cells remaining