Activation of CD14 on circulating monocytes in patients with acute coronary syndrome

Background: Increasing evidence supports the involvement of inflammation in acute phase of coronary artery diseases. Methods: We analyzed the status of activation of inflammatory cells in 38 patients with acute coronary syndrome, 14 stable angina patients, and 19 control subjects by flow-cytometry. Expression levels of CD14 and the percentage of HLA-DR⁺ T-lymphocytes were used as markers of monocyte and T-lymphocytes activation, respectively. Results: The expression of CD14 on monocytes in acute coronary syndrome patients (mean fluorescence intensity±S.D.=158.1±77.1) was increased significantly in comparison to control subjects (57.1±8.0) and the stable angina group (63.6±22.0) (P<0.0001 for both). A significantly higher percentage of HLA-DR positive T-lymphocytes (20.4±9.0 vs. 12.7±3.7%, P<0.01) was observed in acute coronary syndrome patients in comparison to control subjects. Incubation of whole blood cells with bacterial lipopolysaccharide resulted in a 2.4-fold higher secretion of tumor necrosis factor-α in acute coronary syndrome patients than in control subjects (P<0.05). When these markers of activation were measured in acute coronary syndrome patients 6 weeks after medical treatment, a significant reduction both in monocytic CD14 expression and percentage of HLA-DR positive T-lymphocytes (P<0.05 for both) was observed. Discussion: We observed markedly increased levels of monocytic CD14 expression in ACS patients, which appear to indicate the activated status of monocytes and hyper-responsiveness to external stimuli. The CD14 expression levels decreased as the patients were treated, indicating that the expression of CD14 accurately represents the activation status of monocytes during the acute phase of coronary artery diseases.