protein interleukin-17 PR:000001092 Category=family. A protein that is a T cell-derived cytokine that may play an important role in the initiation or maintenance of the proinflammatory response. Except for IL-17B, all other IL-17 family members are homodimers containing five highly conserved cysteine residues forming characteristic cystein-knot structure, similar to that found in the TGF-beta-like cystine-knot (PR:000000008). This class consists of six cytokines. Among them, interleukin 17A (IL-17) and IL-17F are expressed by a novel subset of CD4+ helper T (Th) cells and play a critical role in inflammation and autoimmunity. On the other hand, IL-17E, also called IL-25, has been associated with allergic responses. IL17 protein PIRSF:PIRSF003430