IMMUNOHISTOCHEMICAL LOCALIZATION OF PLASMINOGEN-ACTIVATOR INHIBITOR-1IN HUMAN CORONARY ATHEROSCLEROTIC LESIONS INVOLVED IN ACUTE MYOCARDIAL-INFARCTION

Immunohistochemical localization of plasminogen activator inhibitor-1 (PAI-1) was studied using the streptavidin-biotin method in human athe rosclerotic coronary arteries. The patients (one male and two females) , whose ages ranged from 61 to 78 years, died of anteroseptal acute my ocardial infarction without having received any thrombolytic therapy. PAI-1 immunoreactivities (IRs) were mainly detected in the endothelial cells, smooth muscle cells, and collagen fibers of the coronary arter ial intima and not in thrombi. Remarkable immunohistochemical staining was seen in intimal collagen fibers. In one patient, intimal PAI-1 IR s partly bordered a thrombus and surrounded a large atheroma rich in c holesterol crystals. Our results suggest that PAI-1 is present in both cellular and extracellular components of human coronary atherosclerot ic lesions.