IL17A and rheumatoid arthritis: There is also ample evidence of the presence of autoreactive T cells in the synovium (78), the association of autoreactive T cells with HLA-DR1/4 and T cell-derived cytokines, including interferon gamma (IFN-γ) and interleukin-17 (IL-17) (78), and the clinical efficacy of anti-T cell therapy in RA patients (79).