IL17A and Autoimmunity: These findings are interesting, since it has been postulated, from work in a number of models of autoimmunity, that IL-17-producing cells are not themselves the pathogenic population in such diseases but instead that the critical cells are derived from the Th17 subset and express interferon-γ (IFNγ) as well as, or instead of, IL-17 (“ex-Th17 cells”).