T Cells Flashcards
T/F: An effector T cell is able to respond to specific antigen WITHOUT the need for costimulation?
True; effector T cells can respond to specific antigens without costimulation via B7(CD80)-CD28 interaction
What cytokines cause Th1 cells to proliferate? What cytokines do Th1 cells secrete?
IL-12, IFN-gamma, others that activate DC’s, macrophages, and NK’s
Secrete IL-2, IFN-gamma, and TNF-alpha
What transcription factor leads to Th1 cell development?
T-bet
What is the function of IFN-gamma?
Activates macrophages against intracellular microbes (classical activation), activates B cells to stimulate class switching and complement binding, and stimulates MHC II and B7 (CD80) expression
What is the function of Th1 cells?
Migrate to area of infection, sample antigen presented by macrophages, and fully activate macrophages to become better killers
What cytokine causes Th2 cells to proliferate? What cytokines do Th2 cells secrete?
IL-4
Secrete IL-4, IL-5, IL-13
What transcription factor leads to Th2 cell development?
GATA-3
What is the function of Th2 cells?
Stimulate IgE, mast cell, and eosinophil reactions against helminths; isotope class switching in B cells to IgE; support alternative macrophage development; some IgA class switching can also occur
What cytokine stimulates classically activated macrophages and what cytokines do they secrete? What is their function?
IFN-gamma
IL-1, IL-12, IL-23, and chemokines
Phagocytosis and inflammation
What cytokines stimulate alternatively activated macrophages and what cytokines do they secrete? What is their function?
IL-13 and IL-4
IL-10 and TGF-beta
Anti-inflammatory effects, wound repair, fibrosis
What cytokines cause Th17 cells to proliferate?
What cytokines do they secrete?
IL-1 and IL-6
Secrete IL-17 and IL-22
What transcription factor leads to the development of Th17 cells?
ROR-gamma-t
What is the function of Th17 cells?
Induction of inflammation and leukocyte recruitment in response to bacteria and fungi; they serve an important barrier function
First described in animal models of diseases such as multiple sclerosis, IBD, and RA
What receptor/ligand pair causes weak adhesion of naive T cells to HEV in lymph nodes?
L-selectin/L-selectin ligand
What receptor/ligand pair causes cells to stably arrest on HEV?
LFA-1/ICAM-1
What receptor/ligand pair causes the activation of integrins and chemotaxis through the HEV and to the lymph node?
CCR7/CCL19 or CCL21
What receptor/ligand pair causes weak adhesion of effector and memory T cells to cytokine-activated endothelium at peripheral sites of infection?
E and P selectin ligands/E and P selectins
What receptor/ligand pair causes effector and memory T cells to stably arrest on the endothelium?
LFA-1/ICAM-1 and VLA-4/VCAM-1
What receptor/ligand pair causes the activation of integrins and chemotaxis through the endothelium?
CXCR3/CXCL10
How do tissues retain effector cells that will actually respond to the infection and not effector cells that won’t respond?
New selectins and integrins are expressed when the effector cell is in the right place; if the effector cell is in the wrong place, it re-enters circulation
What effect do Th1 effector cells have on CD8+ T cells?
Enhance proliferation, differentiation, and cloning of activated CD8+ T cells by providing IL-2
What 2 mechanisms do CD8+ T cells use to kill infected host cells?
1) Cytotoxins delivered directly onto the surface of the infected cell; includes granzymes and perforin, which leads to apoptosis
2) FasL on CTL and Fas (CD95) binding on host cell, which induces apoptosis
What is the function of granzymes and perforin?
Granzymes: activate caspases
Perforin: necessary for delivery of granzymes
What is the function of IFN-alpha and beta and what cells produce them?
Inhibit replication of viruses and increases expression of MHC I on other infected cells; produced by NKs and DCs
What is the mechanism of NK cell killing?
Kill tumor cells and virus-infected cells by granzymes and perforin; enhanced by IFN-alpha and beta, IL-12