IL-17 is produced primarily by Th17 type cells and is one of more than 30 interleukins identified to date, ranked 17th by serial number. The family consists of 6 member ligands (IL-17A ~ IL-17F) and 5 receptors (IL-17RA ~ IL-17RD and SEF).IL-17 is an inflammatory cytokine produced primarily by activated T cells, which promotes T cell activation and stimulates the production of a variety of cytokines by epithelial, endothelial, and fibroblast cells, leading to inflammation.