T Cell II (CD4) Flashcards
What is the main function of CD4 cells?
Activate phagocytes and B cells
What happens to the levels of CD40L expression after CD4 activation and what does it bind?
Increases after activation and interacts with macrophages, B cells, and dendritic cells (remember still need cytokines)
Which cytokines activate TH1 cells?
IFN-gamma from NK cells and IL-12 from DCs or macrophages
Which txn factors are required for TH1 differentiation?
STAT1, STAT4, and Tbet
Which cytokines activate TH2 cells?
IL-4 from mast cells
Which txn factors are required for TH2 differentiation?
STAT6, GATA-3
Which cytokines activate TH17 cells?
TGF-beta, IL-6, and IL-23 from macrophages and DCs
Which txn factors are required for TH17 differentiation?
STAT3 and ROR-gammaI
Which cytokines activate TH9 cells?
TGF-beta and IL-4
Which cytokines activate TfH cells?
IL-6
What is the overall function of TH1 cells?
Macrophage and B-cell activation to kill intracellular bacteria
What is the function of TH9 cells?
allergic inflammation
What is the function of TfH cells?
Antibody generation for B-cell dependent responses
Which cytokines do TH1 cells release?
IFN-gamma
What are the functions of IFN-gamma released by TH1 cells?
- B cell complement binding and opsonization with IgG
2. Classical macrophage activation (most important effect)
What do macrophages do after being stimulated by IFN-gamma released by TH1 cells?
Produce reactive oxygen species (NO)
Secrete TNF, IL-1, IL-2 for leukocyte recruitment
Increase MHC expression for increased T cell activation
What is a consequence of TH1 over activation?
Autoimmunity
What is the overall function of TH2 cells?
Phagocyte-independent eosinophil-mediated immunity against helminths
What cytokines do TH2 cells release?
IL-4, IL-5, and IL-13
What is the effect of IL-13,IL-14 release by TH2 cells in terms of macrophages?
Activation of the alternative macrophage pathway for tissue protection and repair
What is the function of IL-4 released from TH2 cells in terms of B cells?
B cell activation and antibody production. Causes IgE release that causes mast cell degeneration
What is the function of IL-5 released by TH2 cells?
Eosinophil activation**
What is the importance of the two different TH1 and TH2 macrophage activation pathways?
Balance of TH1 activation of classical pathway and TH2 activation of alternative pathway determines ability to fight infection
What is the function of TH17 cells?
Pro-inflammation for extracellular bacteria and fungi
Which cytokines do TH17 cells release?
IL-17 and IL-22
What is the function of IL-17 released by TH17 cells?
Stimulates acute inflammation and release of other cytokines (chemokines, TNF, IL-1, IL-6).
TNF = neutrophil and macrophage recruitment
What is the function of IL-22 released by TH17 cells?
Maintained epithelial barrier function.
What do both IL-17 and IL-22 released from TH17 cells stimulate?
Antimicrobial production
What is the clinical relevance of TH17 activity?
May take part in chronic inflammation because has widespread effects on the body
What microbes do CD4’s mainly fight?
bacteria and parasites NOT viruses (extracellular)
