RESPONSE OF THE CELLULAR IMMUNE-SYSTEM TO CARDIOPULMONARY BYPASS IN-VIVO

Cardiopulmonary bypass (CPB) is known to induce an inflammatory respon se. Previous studies reported an impairment of the cellular immune res ponse with activation of neutrophils and changes in lymphocyte subpopu lations. The objective of the present study was to investigate the eff ect of CPB on leukocyte activation in vivo. In 27 patients undergoing coronary artery bypass grafting, the quantitative and the qualitative response of leukocyte populations to CPB was analysed pre-, intra-, an d postoperatively using flow cytometry. A significant increase in leuk ocyte counts was detected during CPB, resulting in a marked leukocytos is postoperatively. The total number of lymphocytes peaked in the earl y phase of CPB, followed by a significant decrease, mainly due to a lo ss in B and cytotoxic T lymphocytes, In contrast, the lymphocytopenia observed 8 h after protamin administration was mainly caused by a drop in the population of helper T lymphocytes. Activation of distinct cel l populations could be detected during and following CPB. The results indicate an influence of CPB on the cellular immune system, however an immune-suppression was detectable only transiently.