Fibrinolysis in cornea and conjunctiva: evidence of two types of activators.

The nature of corneal and conjunctival plasminogen activators (PAs) from human and rabbit eyes was examined in tissue culture. The fibrinolytic activity of culture fluid from human corneas was low, roughly one-eighth of that of rabbits. The main activity was found to be of the urokinase (UK) type, as demonstrated by crossed immunoelectrophoresis against alpha 2-antiplasmin after incubation with mixed plasma. The fibrinolytic activity of culture fluid from human conjunctival tissue was higher and a mixed secretion of tissue type (tPA) and UK activator was demonstrated. These activators were separated by affinity chromatography against Sepharose-immobilized antibodies against tPA. Fibrinolytic activity in tears was quenched by antibodies against tPA but not by the use of anti-UK antibodies. Thus, in man, tear fibrinolytic activity may depend primarily on a release of PAs from conjunctival tissue.