Secretion of plasminogen activator inhibitor by cultured human epidermal cells

A conditioned medium from cultured human epidermal cells was observed to inhibit the activity of exogenous urokinase. By reverse fibrin autography after SDS polyacrylamide gel electrophoresis, a plasminogen activator inhibitor was detected with a molecular weight of 46,000. Using Mr 33,000 [125I]-labelled urokinase we observed the formation of an enzyme-ligand complex. The molecular weight of this complex was 79, 000. These results indicate that cultured human epidermal cells secrete a plasminogen activator inhibitor (urokinase inhibitor) with a molecular weight of 46,000.