IL17A and autoimmune disease: Collectively, we speculate that the IL-17+ FoxP3+ cells found here partially originate from cells with increased susceptibility to Th17 plasticity – expressing low levels of FoxP3 or predominantly expressing FoxP3Δ2. IL-17+ FoxP3+ T cells are present in inflammatory lesions in autoimmune diseases such as rheumatoid arthritis27, psoriasis28 and inflammatory bowel disease29.