Interleukin?17A (IL?17A), also known as CTLA?8, is a 15?20 kDa glycosylated cytokine that plays an important role in anti?microbial and chronic inflammation. The six IL?17 cytokines (IL?17A?F) are encoded by separate genes but adopt a conserved cystine knot fold .IL-17A is a ligand for IL17RA and IL17RC. The heterodimer formed by IL17A and IL17F is a ligand for the heterodimeric complex formed by IL17RA and IL17RC . Involved in inducing stromal cells to produce proinflammatory and hematopoietic cytokines.