TNF and rheumatoid arthritis: As expected, TNFα concentration was higher in RA than in OA synovial fluids (9.2 (± 4.5) pg/mL versus 231 (± 168)) and IL-1β (1.2 (± 0.37) pg/mL versus 15.8 (± 6.2) pg/mL for OA and RA patients, resp).