Tissue factor expression on macrophages in coronary plaques in patients with unstable angina

Abstract

Tissue factor is a membrane-bound glycoprotein that functions in the oxtrinsic pathway of blood coagulation by acting as a cofactor for factor VII, and the resulting complex leads to thrombin production in vivo. The purpose of the present study is to determine whether macrophages express tissue factor in human coronary atherosclerotic plaques. We examined directional coronary atherectomy specimens from 24 patients with unstable angina and 23 with stable exertional angina. In these specimens, macrophages were detected in 22 (92%) of 24 patients with unstable angina versus 12 (52%) of 23 with stable exertional angina (P=.003). The percentage of macrophage infiltration area was significantly larger in patients with unstable angina than in those with stable exertional angina (17±3% versus 6±2%, P=.008). The immunohistochemical double staining revealed the expression of tissue factor on macrophages in 18 (75%) of 24 patients with unstable angina versus 3 (13%) of 23 with stable exertional angina (P