Abnormal levels of urokinase plasminogen activator protein and tissue plasminogen activator activity in human aortic aneurysms.

ABSTRACT

OBJECTIVE: To measure the concentrations and activities of plasminogen activators and plasminogen activator inhibitors in human abdominal aneurysms. DESIGN: Laboratory study. SETTING: University hospital, Sweden. MATERIAL: Biopsy specimens from 12 abdominal aortic aneurysms and 8 normal aortas (controls). INTRERVENTIONS Tissues were homogenised and eluted. The supernatants were assayed for antigens of tissue and urokinase plasminogen activator and plasminogen activator inhibitor 1 and 2. The activities of tissue plasminogen activator and plasminogen activator inhibitor-1 were assayed by ELISA. Frozen sections were immunostained for tissue and urokinase plasminogen activators and for plasminogen activator inhibitor-1. MAIN OUTCOME MEASURES: Concentrations and activities of these activators and inhibitors. RESULTS: The concentration of urokinase plasminogen activator antigen was higher in aneurysmal walls than in normal aortas; it was detected immunohistochemically in aneurysmal but not in normal aortas. The concentration (and the detection immunohistochemically) of tissue plasminogen activator was equal in aneurysmal and normal aortas, but its activity was reduced in the aneurysmal wall. Plasminogen activator inhibitor-1 did not differ significantly between the groups. CONCLUSIONS: Urokinase plasminogen activator may be responsible for the digestion of the media of the aorta and the development of an aneurysm. Reduced activity of tissue plasminogen activator may be responsible for thrombosis in the aneurysm.