A role for IL-17 in autoimmunity has been elucidated through mouse studies of experimental autoimmune encephalomyelitis (EAE) and collagen-induced arthritis (CIA), models for multiple sclerosis and rheumatoid arthritis, respectively [14-16], as well as murine lupus models [17,18]. The gene discussed is IL17A; the disease is systemic lupus erythematosus.