| Because cardiopulmonary bypass (CPB) used in open heart operation is a nonophysiological assisting device, it has been found to be associated with a wide variety of immunosuppression. The transient postoperative immunodeficient state may result in an increased risk of infectious complications after CPB.The total T lymphocyte number showed remarkably decreased during CPB, especially helper T cell (Th cell) numbers were decreased constantly, and cytotoxin T cell (Tc cell) numbers were increased. The decreased of Th/Tc ratio is the evidence of impairment of the celluar immunity. Previous studies reported an impairment of the cellular immune response, but it is unclear that the change and the influence factors of peripheral blood lymphocyte activation during cardiopulmonary bypass surgery.CD69 is described to be one of the earliest markers expressed during the activation of lymphocytes. The expression of human leukocyte antigen-DR (HLA-DR) is taking as a maker for later phase (2-4 days after stimulate) of lymphocyte activation. With the developing of immunology, these activation molecules in cell surface can be measured by flow cytometry(FCM) and monoclonal antibodies (McAb) during cardiopulmonary bypass surgery.ObjectiveTo evaluate the influence and significance of cardiopulmonary bypass on expression of activation molecules CD69 and HLA-DR on surface of peripheral blood T lymphocytes (CD3+ cell) during pediatric CPB surgery for congenital heart disease (CHD). We investigated the immunosuppression reasons after CPB surgery by studying the function of lymphocyte activation. Better and sensitive makers which can show the function of cellular immunity want to be found in order to reduce the incidence of infectious complication after CPB.SubjectsCardiopulmonary bypass group: Forty-two children with CHD who had been performed elective operation under CPB from August to December 2001 in the department of cardiovascular surgery, children's hospital of ZheJiang University were included in this study. Twenty patients were male, and twenty-two were female. Median age was 4.74±3.33 (range 0.17-13 ) years old.Non-cardiopulmonary bypass group: Eleven children who had been performed elective operation without CPB at the same days were taken as controls.None of the patients had clinical evidence of acute infection or underlying immune disease, and none were prescribed drug know to interfere with immune response before operation. There was no statistical difference of sex, weight and age between CPB group and Non-CPB group.MethodsTwo milliliter fresh blood samples were taken from peripheral vein at six various time points (preoperative, after CPB 30 minutes and 1, 24, 48, 72 hours postoperative) in CPB group, while fresh blood samples were taken at there various time points(preoperative, 1 and 24 hours postoperative) in Non-CPB group. The samples were stored in heparin-anticoagulated tubes. The samples were stained directly by monoclonal antibodies (McAb) .The expression of CD69 and HLA-DR on peripheral blood CD3+ cell were measured by FACScalibur?flow cytometry (FCM) using Cell Quest?software. All data were analyzed by SPSS for windows software.Results1. No significant difference in expression of activated T lymphocyte at preoperative time between the CPB and Non-CPB group (t=1.143 and 0.649, P>0.05 respectively), and no significant changes in expression of activated T lymphocyte during operation in Non-CPB group (F=0.761 and 0.754, P>0.05 respectively).2. During CPB, the expression of CD69 on CD3+ cell in CPB group were significantly higher than preoperative (1.43 ±0.68 vs 1.10 ± 0.50, P =0.022), and peaked at 1 hour postoperative (2.03 + 0.88 vs 1.10 + 0.50, P O.001). It recovered to preoperative values at 72 hours postoperative (1.14 ± 0.49 vs 1.10 ± 0.50, P =0.739 ). The expression of late phase T lymphocyte activation molecules CD3+/HLA-DR+ started increasing at 1 hour postoperative (3.59±1.45 vs 2.75 ± 1.35, P =0.009), recovered at 48 hours(3.01 ± 1.62 vs 2.75 ±...
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