Interleukin-17F (IL-17F) exists in a disulfide-linked heterodimer that belongs to the IL-17 family. IL-17F is expressed in activated, but not resting, CD4+ T-cells and activated monocytes. IL-17F has been shown to stimulate the production of several other cytokines, including IL-6, IL-8, and granulocyte colony-stimulating factor. IL-17F can regulate cartilage matrix turnover and stimulates PBMC and T-cell proliferation. IL-17F is also found to inhibit the angiogenesis of endothelial cells and induce endothelial cells to produce IL2, TGFB1/TGFB, and monocyte chemoattractant protein-1. Defects in IL-17F are the cause of familial candidiasis type 6 (CANDF6).