Effect of open heart surgery with cardiopulmonary bypass on peripheral blood lymphocyte apoptosis in children.

Children undergoing cardiopulmonary bypass (CPB) operations have an increased risk for the development of immunosuppression and severe infection. Lymphocyte apoptosis plays an important role in regulating immune responses. This study aimed to investigate the effect of open heart surgery with CPB on peripheral blood lymphocyte (PBL) apoptosis and the possible mechanism of lymphocyte apoptosis in infants and young children. This study enrolled 20 consecutive infants and children as a CPB group and 20 age-matched children who underwent patent arterial duct closure without CPB as control subjects. Samples were taken from peripheral blood after induction of anesthesia (preoperatively) and again 24 h after the operations. The degree of apoptosis and the expression level of Fas (CD95) on PBL were measured using flow cytometry. The percentage of lymphocyte apoptosis significantly increased after surgery in both groups, but it was much higher in the children with CPB than in those without CPB (14.46%+/-4.83% vs. 7.33%+/-1.43%; p<0.01). The expression level of Fas in the individuals with CPB was significantly higher than in those without CPB (52.80%+/-8.80% vs. 37.82%+/-6.32%; p<0.01). As shown by the study findings, both surgical stress and CPB can induce PBL apoptosis, which may lead to lymphopenia after open heart surgery with CPB for infants and young children.