6-Sulfanilamidoindazole arthritis of the rat: complement activity and sulfhydryl group concentration of the serum in three different phases of inflammation.

In 6-sulfanilamidoindazole (6-SAI) arthritis the total haemolytic complement activity of the serum was significantly increased by 69% in developing arthritis at day 4, and by 42% in fully developed arthritis at day 8. In declining arthritis at day 12, 5 days after the last administration of the prophlogistic agent 6-SAI, no difference of the serum complement activity between arthritic rats and non-arthritic controls could be determined. The serum SH group concentration was significantly decreased by 31% at day 4 and by 54% at day 8, but it was nearly normalized at day 12. There was no close correlation between increase of paw diameter and serum complement activity in 6-SAI-arthritic rats. It is suggested that investigations on the role that complement components might play in 6-SAI arthritis could be interest.