LOCALIZATION OF FIBRINOLYTIC ACTIVATORS AND INHIBITORS IN NORMAL AND ATHEROSCLEROTIC VESSELS

Local fibrinolytic changes in atherosclerotic arteries have been sugge sted to influence plaque growth and promote mural thrombosis on ruptur ed or ulcerated plaques. Increased levels of plasminogen activator inh ibitor (PAI-1) have been found in atherosclerotic arteries. In this st udy tissue plasminogen activator (t-PA), urokinase-type plasminogen ac tivator (u-PA) and PAI-1 were localized in arterial biopsies of health y and atherosclerotic vessels by immunohistochemistry. The expression of fibrinolytic regulators was related to the distribution of endothel ial cells (EC) and macrophages. Results: t-PA was expressed in vasa va sorum. PAI-1 was positive in endothelial cells, in the media and in th e adventitia. Increased expression of t-PA, u-PA and PAI-1 was found i n atherosclerotic vessels, t-PA, u-PA, PAI-1 and macrophages were co-l ocalized in plaques. These results support the concept that macrophage s can be important in the local regulation of fibrinolysis in atherosc lerotic vessels.