Characterization of a plasminogen activator secreted by cultured bovine aortic endothelial cells

A plasminogen activator was purified from the serum-free conditioned medium of bovine aortic endothelial cell cultures by chromatography on zinc chelate-agarose and benzamidine-CH-Sepharose. The final material consisted of a main fibrinolytically active component with Mr 30,000 and a minor component with Mr 41,000. It was obtained with a yield of 60%, a purification factor of 35 and a purity of 25-50%. The activity of this plasminogen activator was completely neutralized by antibodies to human urokinase but not by antibodies against human tissue plasminogen activator. Purified tissue plasminogen activator from bovine heart, however, was completely neutralized by antibodies against human tissue plasminogen activator but unaffected by antibodies to human urokinase. These findings indicate that bovine aortic endothelial cells in culture secrete mainly a urokinase-like. These findings indicate that bovine aortic endothelial cells in culture secrete mainly a urokinase-like plasminogen activator, and not a tissue-type plasminogen activator as was generally assumed.