Abstract 8399: Circulating Mononuclear Cells with Class A Macrophage Scavenger Receptor Were Specifically Increased in Patients with Acute Coronary Syndrome

Abstract

Objective: We previously remarked that class A macrophage scavenger receptor (SR-A), in peripheral blood mononuclear cells (PBMCs), was a candidate as a predictive marker for acute coronary syndrome (ACS) utilizing a gene chip microarray system. Herein, we examined SR-A levels in atherosclerotic lesions and in circulating monomuclear cells. Methods and Results: We obtained atherosclerotic lesion samples utilizing directional coronary atherectomies: 11 consecutive patients with unstable angina (UA); and, 13 consecutive patients with stable exertional angina (SEA). Immunohistochemical analyses revealed that SR-A was abundantly expressed in the macrophages of UA patients. SR-A mRNA levels of the atherosclerotic lesions in the UA patients and in the SEA patients were 3.8±1.5 and 1.0±0.6, respectively. SR-A mRNA levels of the coronary atherosclerotic lesions were significantly higher in the UA patients than in the SEA patients (p<0.03). Utilizing flow cytometric analysis, PBMCs were collected from 255 subjects: 67 consecutive ACS patients; 87 consecutive SEA patients; and, 101 controls. The frequencies of CD14-positive PBMCs (monocytes), that stained for SR-A, were 1.9±1.6% , 0.7±0.5% , and 0.7±0.5%, respectively. The frequency of SR-A positive monocytes was significantly higher in the ACS Group than in either the SEA or Control Groups (p<0.001); however, there were no significant differences between the Control and SEA Groups. There were no significant differences in the frequencies of SR-A positive monocytes between the patients with UA and the patients with acute myocardial infarction. In the ACS Group, the frequencies of SR-A positive monocytes at onset, at 1 day and at 7 days after onset, were 1.7±1.1%, 1.1±0.8%, and 1.1±0.5%, respectively. The frequency of SR-A positive monocytes in the ACS Group was significantly decreased within 24 hours of onset receiving orthodox medical treatment (p<0.01). Conclusion: The SR-A level increases in unstable atherosclerotic plaque, as well as in the PBMCs in ACS patients. SR-A is a well known macrophage marker. The detection of SR-A positive monocytes in the peripheral circulating blood provides crucial clinically and pathophysiologicaly significant information about unstable plaque in ACS patients.