TNF and rheumatoid arthritis: The frequencies of circulating Th17 cells were positively correlated with DAS28 scores (r = 0.294, P < 0.05), IL-17 levels (r = 0.737, P < 0.001), IL-6 levels (r = 0.347, P < 0.05), and TNF-α levels (r = 0.495, P < 0.001) in RA patients before the anti-TNF-α therapy was started.