Given that the onset and progression of autoimmune diseases (including rheumatoid arthritis (RA)) are mediated by proinflammatory cytokines released into the inflammatory site, we investigated the effect of 15d-PGJ2 treatment upon the production of TNF-α, IFN-γ, IL-17, and IL-12 in affected ankle joints. This evidence concerns the gene TNF and rheumatoid arthritis.