The world according to Th17 cells. Th17 cell induction occurs through combination of IL-6 and TGFβ, or IL-21 and TGFβ—in the absence of IL-6. The Th17 lineage produces cytokines which include IL-17A, IL-17F, IL-22, IL-21, GM-CSF, TNFα, IL-9, IL-10, and IFNγ. This population is enhanced through IL-23, IL-1β, TNFα, and high levels of sodium. Conversely, IL-25, IL-27, IL-2, SOCS3, SOCS1, Vitamin D, and retinoic acid serve to negatively regulate Th17 cells.
