Table 1. Main STAT3 modulators and their effects in immune cells.

Cell type	pSTAT3 modulators	Effects
CD4+ T cell	IL-27	↑ proliferation
Th17	IL-6, IL-21, IL-23	↑ RORγt and RORα expression and ↑ cell differentiation ↑ IL-21, IL-23R and IL-17
	IL-6 (in combination with TGF-β)	↑ CD39 and CD73 expression and ↑ adenosine production
Treg	IL-2	↑ Foxp3 expression (associated with pSTAT5) and ↑ inhibitory functions
	IL-6, IL-27	↓ Foxp3 expression (with an inhibition of pSTAT5 binding) and inhibition of differentiation
		↑ IL-6, TGF-β (with Foxp3 cooperation)
Macrophage	IL-6	Inhibition of differentiation
		Inhibition of Ag presentation to CTL, ↑ IL-23 and ↓ IL-12 production Inhibition of LPS-mediated cytokine production (e.g., RANTES and IL-12)
	Tumor cell supernatants	↑ IL-10, βFGF and VEGF-A production and ↑ angiogenesis
DC		Inhibition of Ag presentation to CTL and ↓ TLR induced IL-12 and TNF-α production
	Tumor cell supernatants, IL-6 and exosomes	↓ differentiation (with an IL-6 amplification loop)
MDSC	exosomes	↑ immunosuppressive functions (with an IL-6 amplification loop)
	Tumor cell supernatant	↑ production of VEGF and βFGF and ↑ angiogenesis
		↑ expression of NOX2, ↑ production of ROS and ↑ immunosuppressive functions