Table 1.

Role of cytokines and chemokines in TH cell differentiation.

	TH1	TH2	TH9	TH17	TFH
Differentiation Factors	IL-2, IL-12, IFN-γ, IFN-α	GATA3, IL-4, IL-6	GATA3, IL-6, PU.1, TGF-β	TGF-β, IL-6, RORγt, STAT3	Bcl6, ICOS, IL-6, IL-21, STAT3
Secreted Cytokines	IL-1β, IL-2, IL-12, TNF-α, IFN-γ	IL-4, IL-5, IL-10, TGF-β	IL-9, IL-3, IL-21	IL-17A, IL-17F, IL-21, IL-22, IL-23	IL-21, IL-4
Chemokines and cognate receptors	CXCR3, CCR5, and CCR7, CXCL9, CXCL10, CXCL11,	CCR3, CCR4, and CCR8, MDC, TCA3, TARC	CCL20, CCR6,	CCL4, CCL17, CCL22	CXCR3, CCR6
Classical Negative Regulatory Cytokines	IL-4	IL-12	IFN-γ/IRF-1	IL-12, IFN-γ	IL-2
Significant Downstream Signaling Pathways	IRF1, STAT1, MAPK, STAT3	STAT5, STAT6	STAT6, IRF-4	STAT3	STAT3