Immunological characterization of plasminogen activators in human parotid saliva

These were characterized in stimulated saliva from 21 healthy volunteers using antibodies specific for human tissue-type plasminogen activator (t-PA) or urokinase. After pre-incubation with immunoglobulins, with and without specific antibodies, the fibrinolytic activity was assayed on fibrin plates containing plasminogen. Fibrinolytic activity was demonstrated in all salivas but one; it was completely quenched by antibodies against t-PA, but antibodies against urokinase-like plasminogen activator had no effect. The fibrinolytic activity was expressed in international units (IU) using a standard curve obtained by serial dilution of the international tissue-plasminogen standard. The normal range was 0.05-0.35 IU/ml, and the maximal value 2 IU/ml. There is thus considerable individual variation in fibrinolytic activity in parotid saliva, where it is regulated by t-PA under physiological conditions.