TNF and rheumatoid arthritis: Next, we assessed the concentrations of cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, INF-γ, INF-α, TNF-α, IL-12P70) and found that IL-1β, IL-6 and IL-8 were elevated significantly in the synovial fluid of RA compared to OA (Fig. 1b).