Chain breaking antioxidant status in rheumatoid arthritis: clinical and laboratory correlates.

The ability of fresh sera to resist attack by peroxyl radicals (TRAP) was found to be significantly lower in 20 patients with rheumatoid arthritis (RA) than in 20 healthy controls, consistent with the existence of a redox stress in RA imposed by inflammation. TRAP values in RA varied inversely with a combination of visual analogue pain scale, duration of early morning stiffness, grip strength, and articular index (reflecting inflammatory activity) using multiple linear regression analysis. The concentration of the antioxidant vitamin ascorbic acid was lower in RA plasma and the oxidation-reduction equilibrium of ascorbic acid was disturbed, giving further support to the existence of a redox stress. The major determinant of TRAP in vitro was found to be serum uric acid in RA and serum vitamin E in controls. Serum urate concentration in RA correlated inversely with oxidative changes in serum albumin and IgG. It is suggested that serum urate might have an antioxidant role under certain conditions by limiting free radical induced oxidative changes to protein during inflammation.