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Th1 characteristics
- Develop from CD4+ cells in response to IL12
- Secrete gamma-IFN, TNF, and express CCR5
- gamma-IFN functions:
- activate macrophage phagocytic activity
- increase MHC expression on other APCs
- change antigen processing components of proteosome
- may signal to uninfected cells in the tissue to upregulate antiviral activities
- important for clearing intracellular bacteria, viruses, parasites
- examples: mycobacterium tuberculosis, listeria monocytogenes, influenza, T. gondii
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6 cytokines produced by Th1 and their functions
- IFN-gamma/CD40L: increase phagocytosis
- Fas-L: kills host cell, releasing bacteria for phagocytosis
- IL2: T cell growth factor
- IL3: induce macrophage differentiation in bone marrow
- TNF-alpha: increase endothelium permeability so cells can enter infected tissue
- CCL2: case macrophage accumulation at infection site
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Th2 characteristics
- Develop in response to IL4
- Secrete IL3, IL4, IL5, IL13 and express CCR3
- CCR3 targets Th2 to GC to find B cells
- IL4 promote B cell isotype class switching
- IL5 attract and activate eosinophils
- enhance IgE release by B cell associated w/ allergies
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Th17 characteristics
- develop in response to IL1, IL6, and TGF-beta
- secrete IL17, IL21, IL22
- IL17--> acts on most cells --> release CXCL8 and CXCL2 --> attract neutrophil/macrophages in infection site
- important for extracellular pathogens in gut
- hyper IgE syndrom: low Th17 cells, susceptible to chronic fungal/viral infections
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Treg characteristics
- unknown inducing agent
- Foxp3 is the key transcription factor for their development
- secretes IL10
- Function: Suppress T cell activation to self, peripheral tolerance
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5 gamma-IFN functions
- activate macrophage phagocytic activity
- increase MHC expression on other APCs
- change antigen processing components of proteosome
- may signal to uninfected cells in the tissue to upregulate antiviral activities
- important for clearing intracellular bacteria, viruses, parasites
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