RESUMO
It is well known that lymphocytes play a major role in coronary plaque destabilization in acute coronary syndromes. The aim of this study was to evaluate circulating lymphocyte apoptosis in patients with non-ST elevation myocardial infarction (NSTEMI) in comparison with subjects with stable angina and with healthy controls. We considered spontaneous lymphomonocyte apoptosis (evaluated by ELISA), interleukin (IL)-2 production (evaluated by ELISA), Fas expression on T cells (evaluated by flow cytometry) and Fas ligand mRNA (evaluated by reverse transcriptase polymerase chain reaction), as well as Fas functionality. To evaluate T-cell activation, we also investigated T-cell subpopulations (CD4/CD8 ratio), T-cell surface HLA-DR and CD69 expression (evaluated by flow cytometry) in blood taken within 6 hours from onset of NSTEMI. Spontaneous apoptosis was significantly increased in NSTEMI patients in comparison with the two control groups and it was associated with an increased expression of Fas, an increased susceptibility to the Fas agonist (CH-11) and a normal production of IL-2 in cell cultures. We also found a significant increase of HLA-DR+ CD3+ and CD69+ CD4+ cells in NSTEMI patients. These data suggest that the enhanced apoptosis is due to a mechanism of "active" antigen-driven death, induced by the expression of death cytokines and not by the failure of cell growth factors. We conclude that in case of NSTEMI peripheral lymphocytes are activated and undergo an enhanced programmed cell death due to activation mechanisms. It is likely that lymphocyte activation occurs before the onset of acute ischemia and contributes to the plaque rupture and to the myocardial ischemic insult.
