Circulating Regulatory B-Lymphocytes in Patients with Acute Myocardial Infarction: A Pilot Study.

Background: Inflammation plays on important role in plaque instability and acute coronary syndromes. The anti-inflammatory effects of B-regulatory lymphocytes (B-regs) in atherosclerosis was tested mainly in animal models with inconclusive results. Herein, we studied for the first time, levels of circulating B-regs in patients with acute myocardial infarction (MI). Methods: We examined circulating levels of B-regs by flow cytometry in 29 patients with recent ST-segment elevation MI and 18 patients with stable angina pectoris (SAP) and coronary artery disease. We re-assessed B-reg levels on average 4 months later. Results: The mean level of CD20+ cells was similar in patients with MI and patients with SAP (p = 0.60). The levels of CD24hiCD38hi cells among CD20+ cells were 5.7 ± 4% and 11.6 ± 6% in patients with MI and SAP, respectively, (p < 0.001). The level of CD24hiCD38hi B-regs remained related to acute MI after correcting for age, gender, and risk factors. Circulating levels of CD24hiCD38hi B-regs in patients with MI did not change significantly at follow-up in a small patient groups (p = 0.408). Conclusions: Circulating B-regs are reduced in patients with MI compared to patients with SAP. This finding may shed further light on the inflammatory pathophysiologic factors related to plaque rupture.