A lysine-absorbable plasminogen activator is elevated in conditions associated with increased fibrinolytic activity.

A plasminogen activator, or class of activators, that absorbs to lysine-agarose is present in human plasma. We have developed a quantitative assay for this plasminogen activator. The assay involves removal of the activator from plasma with lysine-agarose affinity columns and subsequent measurement of the activity by the conversion of plasminogen to plasmin on standardized fibrin agar plates. Using this assay, we investigated three physiologic conditions that have in the past been associated with increased fibrinolytic activity to determine whether elevation of the LAPA was involved. Normal individuals undergoing strenuous physical exercise and others subjected to venous occlusion as well as patients with cirrhosis of the liver were examined. Treadmill exercise to maximal exertion produced up to 15-fold increases in the level of LAPA; venous occlusion produced similar elevation. Certain individuals did not show increase fibrinolytic activity in response to exercise or venous occlusion, as indicated by unchanged euglobulin lysis times. These fibrinolytic hyporesponders did not show an elevation of their LAPA levels. In the third group examined, patients with cirrhosis, 24 of 62 had elevated levels of LAPA. Supplementation of plasma from normal individuals with this plasminogen activator from exercised individuals and cirrhotics resulted in increased rates of clot lysis.