Interleukin 17A (IL-17 or IL-17A), originally identified as a transcript from a rodent T-cell hybridoma by Rouvier et al. in 1993, is the founding member of a group of cytokines called the IL-17 family. Known as CTLA8 in rodents, IL-17 shows high homology to viral IL-17 encoded by an open reading frame of the T-lymphotropic rhadinovirus Herpesvirus saimiri.