Effect of the common bile acids on the fibrin/fibrinogen fragments in rheumatoid synovial fluid. A possible clue to the ameliorating effect of jaundice in rheumatoid arthritis.

Fibrin/fibrinogen degradation products observed in rheumatoid synovial fluid exhibit resistance to plasmin proteolysis. In the present study, the influence of the common bile acids on the plasmin digestion of these degradation products in 16 rheumatoid synovial fluids were quantitated immunologically by radial immunodiffusion, and qualitatively estimated by crossed immunoelectrophoresis. Addition of chenodeoxycholic acid, deoxycholic acid, and their taurine and glycine conjugates in concentrations of 3.33 mumole/ml of a mixture of rheumatoid synovial fluid and plasmin resulted in complete plasmin degradation. Cholic acid and its taurine and glycine conjugates were effective only in concentrations of 4.44 mumole/ml. A detergent, such as Triton X-100, had little or no effect on the plasmin digestion. Other proteins capable of influencing fibrinolytic activity, such as plasminogen and the inhibitors alpha1-antitrypsin and alpha2-macroglobulin, were not affected by the two detergents. The bile acids are thought to influence the fibrin/fibrinogen degradation products by unfolding the protein at a molecular level, by virtue of their properties as steroid detergents, leaving the fibrin/fibrinogen degradation products susceptible to plasmin digestion.