Immunological characterization of plasminogen activator activities in human tissues and body fluids

Human plasminogen activators were compared immunologically in both a double-diffusion technique and quenching experiments on the fibrinolytic activities of the activators. Antisera against HMW and LMW urokinase and an antiserum against highly purified tissue plasminogen activator from human uterus were used. It was found that uterine tissue plasminogen activator and urokinase are two immunologically distinct plasminogen activators. The occurrence of the two kinds of plasminogen activators in human tissues and body fluids was studied on the basis of the quenching of the activities by antibodies. In tissue extracts, mainly tissue plasminogen activator was found. Seminal plasma exhibited a high plasminogen activator activity, consisting of both urokinase and tissue plasminogen activator-related activators. Urine contained a small amount of tissue plasminogen activator-related activator in addition to urokinase. The low plasminogen activator activities of saliva and tears were completely attributed to activators related to tissue plasminogen activator.