Activators and inhibitors of fibrinolysis in rheumatoid and nonrheumatoid synovial membranes. A histochemical study.

Histochemical studies of rheumatoid and nonrheumatoid synovial membranes revealed lowered fibrinolytic activity at sites of chronic inflammatory infiltrates and deposits of fibrin-like material (FLM). Inhibition of fibrinolysis occcurred over these areas and was always inversely related to the fibrinolytic activity. Hence the low fibrinolytic activity of these chronically inflamed tissues seems to result from the presence of inhibitors of fibrinolysis. Such inhibitors in FLM deposits may be responsible for the prolonged persistence of these deposits in the rheumatoid joint.