Hematologic and serologic studies in 6-sulfanilamidoindazole arthritis.

6-sulfanilamidoindazole (6-SAI), an antibacterial sulfonamide, is known to cause an acute, self-limited inflammatory reaction in the hind paws of older rats. Administration of 6-SAI results in hyperfibrinogenemia which precedes the onset of clinical arthritis. The hyperfibrinogenemia is associated with the prolongation of dilute blood clot lysis times, appearance of heparin-precipitable fibrinogen, elevations in fibrin degradation products, and complement titers and serum electrophoretic pattern changes that consist of decreased albumin concentrations and increased beta globulin concentrations. Alterations in 6-SAI medicated young rats are less marked and require higher doses.