Frequency of naturally-occurring regulatory T cells is reduced in patients with ST-segment elevation myocardial infarction

BackgroundNaturally-occurring regulatory T cells (Treg) constitute a mature T-cell population characterized phenotypically by co-expression of CD4 and CD25high surface molecules. We investigated here the frequency of circulating Treg in patients presenting with STEMI in comparison with subjects without coronary artery disease (CAD). The effect of primary percutaneous coronary intervention (PCI) with implantation of a bare (BS) or paclitaxel-eluting stent (PES) on peripheral Treg distribution was also examined.MethodsPeripheral blood mononuclear cells were isolated from 30 consecutive patients presenting with STEMI and from 30 age-matched control subjects with angiographically normal coronary arteries. Treg were detected by flow cytometry according to their characteristic CD4+CD25high membrane phenotype, and their frequency was assessed before PCI and at 48 h and at 6 days after PCI. CD27 expression identifying a highly suppressive Treg subset was also analysed.ResultsThe percentages of both CD27+Treg and CD27-Treg were significantly lower in patients with STEMI in comparison with controls. In addition, the CD27+Treg/CD27-Treg ratio was skewed toward the CD27− population. The frequency of both Treg subsets significantly increased 48 h after either BS or PES implantation, remaining elevated for up to at least 6 days after PCI.ConclusionsOur data suggest that the percentage of circulating Treg is significantly reduced in patients with STEMI, suggesting that this immunosuppressive T-cell subset is compartmentalized within the acutely ischemic myocardium to limit the ongoing inflammation associated with this condition, and that coronary revascularization is associated with partial reconstitution of peripheral Treg pool.