T cell effectors Flashcards
What cytokines are needed for a naive CD4+ T cell to develop into a Th1 cell?
**IFNγ **(produced by NK cells)
IL-12 (produced and secreted by DCs or MØs)
What transcription factors are needed for a naive CD4+ T cell to develop into a Th1 cell?
T-bet
What cytokines to Th1 cells produce?
IFN-γ
TNF
What kind of pathogens do Th1 cells target?
Intracellular pathogens b/c Th1 cells are engaged in host defense
What pathogenic process are Th1 cells involved in?
Autoimmunity
What activities are Th1 cells engaged in?
- Activate macrophages via CD40-CD40L interaction and IFN-gamma (Help phagocytosis)
- Stimulate B cell class-switch to IgG3 (great opsonizer), while suppressing IgG4 (Help opsonization)
What does IFN-gamma do?
IFN-gamma triggers the JAK-STAT pathway to:
Activate MØs → enhanced killing of phagocytosed bacteria & secretion of inflammatory cytokines
Upregulate MHC class I and II expression by APCs
Upregulate expression of costimulatory molecules (e.g., CD40, B7 on APCs)
Promote CD4+ differentiation into Th1 cells and inhibit differentiation into Th2 cells
What cytokines are needed for a naive CD4+ T cell to develop into a Th2 cell?
**IL-4 **(produced and secreted by DCs and mast cells)
What transcription factors are needed for a naive CD4+ T cell to develop into a Th2 cell?
GATA3
What cytokines do Th2 cells produce?
IL-4
IL-5
IL-13
What kind of pathogens do Th2 cells target?
What else are they responsible for?
Parasites (e.g., helminths) b/c they are also involved in host defense
They are also responsible for allergy and asthma
- Th2 cells cause:
- mast cell proliferation
- B cell isotype switching to IgE
- Proliferation of B cells
What pathogenic process are Th2 cells involved in?
Tumor growth (cancer)
What does IL-4 do?
- Stimulates development of Th2 cells
- Stimulates B cell isotype switching to IgG4 (inhibit IgG3)
- With IL-13:
- Stimulates leukocyte recruitment
What does IL-5 do?
Activates eosinophils
What cytokines are needed for a naive CD4+ T cell to develop into a Th17 cell?
TGF-β
IL-6 (produced and secreted by DCs)
What transcription factors are needed for a naive CD4+ T cell to develop into a Th17 cell?
RORγT
What cytokines do Th17 cells produce?
IL-17
IL-21
What kind of pathogens do Th17 cells target?
Extracellular pathogens (e.g., bacteria, fungi) b/c they also engage in host defense
What effect do Th17 cells have on certain innate immune system cells?
They ⇡chemokine & cytokine production in MØs, neutrophils, and endothelial cells.
What pathogenic processes are Th17 cells involved in?
**Inflammation **
Autoimmunity (heavily)
What cytokines are needed for a naive CD4+ T cell to develop into a Treg cell?
TGF-β
What transcription factors are needed for a naive CD4+ T cell to develop into a Treg cell?
FOXP3
What cytokines do Treg cells produce?
TGF-β
IL-10
What is the function of Treg cells?
Immunosuppression
What cytokines and cytotoxins do CD8+ T cells secrete?
- Cytokines:
- IFN-γ
- LT
- Cytotoxins:
- Perforin
- Granzyme
NK Cells
= Lymphocytes (comprise 8-10% of peripheral blood lymphocytes)
- Release perforin and granzyme
- Do not require CD4+ T cell help
- See less MHC Class I
- Mainly attacks sick cells
CD56
CTLs
= CD8+ T cells
- Release perforin and granzyme
- **Require **CD4+ T cell help
- Require MHC Class I and only works if cells have antigen on cell surface/MHCI pocket
- Mainly involved in graft rejection
What does LFA-1 do?
- LFA-1 is an adhesion molecule on CD8+ T cells that binds to ICAM-1 on target cells
- LFA-1 & ICAM-1 interaction:
- maintains close apposition b/w CTL and target cell
- helps prevent collateral damage to other host cells and the CTL itself by triggering cytoskeletal rearrangement in the CTL that leads to granule accumulation mostly at the site of contact b/w the CTL and target cell → target cell death (w/o death of other host cells)
What does FasL do?
- FasL on CTLs interacts with Fas on target cells → apoptosis of target cells
- Immune-priviledged sites have Fas
