AimTo investigate the circulating CD4^＋CD25^＋CD127^lo regulatory T cells (Tregs) levels in patients with acute myocardial infarction (AMI) and controls.Furthermore, to determine the relation between initial Tregs levels and cardiac function, the severity of coronary atherosclerosis and prognosis.Methods114 patients with AMI (86 with ST-segment elevation myocardial infarction (STEMI) and 28 with non-ST-segment elevation myocardial infarction (NSTEMI)) and 38 normal subjects were enrolled.Initial circulating Tregs levels were measured using flow cytometry in all subjects at entry.In 114 patients with AMI, heart function was evaluated by serum B-type brain natriuretic peptide (BNP) and left ventricular ejection fraction (LVEF) determined by echocardiogram.SYNTAX score and the number of affected main vessels were obtained to reflect the severity of coronary atherosclerosis.At one-month after discharge, information about reoccurrence of angina pectoris and NYHA heart function classification was obtained by outpatient follow-up.ResultsLevels of circulating Tregs were lower in patients with AMI at admission in comparison with normal subjects (2.04%±1.20% vs 3.68%±1.15%, p＜0.01).No significant differences in circulating Tregs levels were observed