Interleukin 17 (IL-17) is a pro-inflammatory cytokine produced by a subset of T helper cells that develops distinct from the Th1- and Th2- cell differentiation pathways. IL-17, also known as CTLA-8, stimulates induction of other pro-inflammatory cytokines TNF alpha, IL-1 beta, IL-6, and IL-8, and reports strongly suggest the involvement of IL-17 in several chronic inflammatory diseases such as rheumatoid arthritis, psoriasis and multiple sclerosis. TGF-ß (differentiation) and IL-23 (expansion) are required for induction and maintenance of Th17 (IL-17 producing) cells, which in turn induce the other pro-inflammatory cytokines. IL-17 (~32 kDa) protein is produced and exists as a homo-dimer, has homology to a herpes virus early protein, is one of the six members (IL-17A-F) of this cytokine family, and is well characterzed and highly expressed by activated effector memory T cells.Synonyms: CTLA-8, CTLA8, Cytotoxic T-lymphocyte-associated antigen 8, IL-17, IL-17A, IL17