Fibrinogen‐fibrin breakdown products in pathologic synovial fluids. An immunologic study

Fibrinogen‐fibrin breakdown products in inflammatory and non‐inflammatory synovial fluids have been quantitated immunologically by hemagglutination inhibition immunoassays and radial immunodiffusion and qualitatively by conventional and crossed immunoelectrophoresis. Huge amounts of breakdown products are found in inflammatory fluids, mostly in complex formation unclottable by thrombin but precipitable by protamine sulfate. In non‐inflammatory cases the amounts of fibrinogen antigenic fractions are much smaller, some are clottable by thrombin while protamine sulfate precipitates certain amounts. Fibrinogen‐fibrin fragments in inflammatory synovial fluids exhibit significant resistance to plasmin proteolysis.