Interleukin-17(IL-17 or IL-17A) originally identified as a transcript from a rodent T-cell hybridoma by Rouvier et al, in 1993. The IL-7 gene maps to human chromosome 2q31. It is the founding member of a group of cytokines called the IL-17 family, and secreted primarily by activated T cells. IL-17 shows high homology to viral IL-17 encoded by an open reading frame of the T-lymphotropic rhadinovirus Herpesvirus saimiri. All members of the IL-17 family have a similar protein structure, with four highly conserved cysteine residues critical to their 3-dimensional shape, yet they have no sequence similarity to any other known cytokines. The most notable role of IL-17 is it involvement in inducing and mediating proinflammatory responses. IL-17F has been well characterized both in vitro and in vivo, and has been shown to have a pro-inflammatory role in asthma.