Elevated levels of interleukin-6 (IL-6), prostaglandin (PG)E2, PGD2 and its dehydration end product 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) have been detected in joint synovial fluids from patients with rheumatoid arthritis (RA). The gene discussed is IL6; the disease is rheumatoid arthritis.