A remarkable increase of superoxide dismutase activity in synovial fluid of patients with rheumatoid arthritis.

Superoxide dismutase activities in the synovial fluid of patients with rheumatoid arthritis and osteoarthritis were determined by the technique of McCord and Fridovich. The superoxide dismutase activity from the rheumatoid arthritis group was found to be remarkably higher than that from the osteoarthritis group. The high superoxide dismutase activity of rheumatoid arthritis is correlated with the severity of the disease. A significant correlation was also found between C-reactive protein and superoxide dismutase activity. These observations suggest that superoxide dismutase activity is a manifestation of the acute inflammatory stage of rheumatoid arthritis.