Leukocyte activation and phagocytotic activity in cardiac surgery and infection

Abstract

Background: Cardiac surgery (CS) using cardiopulmonary bypass (CPB) is associated with cellular and humoral defense reactions termed the systemic inflammatory response syndrome. Leukocyte activation is one of its causative mechanisms which may be aggravated by additional infection. Methods and results: Eighty-five patients undergoing CS with CPB were prospectively investigated. Leukocyte counts, elastase, and phagocytotic activity were measured from 24 h preoperatively up to 7 days postoperatively. Seventy-nine patients had an uneventful course (group 1) while six patients developed a systemic infection (group 2). Leukocytes and elastase levels increased postoperatively ( p<0.01) and were significantly higher in group 2 ( p<0.01). In both groups a decrease of leukocyte/elastase ratio occurred ( p<0.002), no differences between groups were observed. The phagocytotic activity, representing the circulating cells of the reticuloendothelial system (RES), dropped on day 1 ( p<0.05), and increased thereafter above baseline levels ( p<0.001). No differences of RES function between groups was observed, the initial drop on day 1 in both groups was compensated by the quality of phagocytotic ability of each cells. Conclusion: Leukocyte activation after CS with CPB occurs. It is associated with a regular RES function and similarly leukocyte/elastase ratios in both groups, suggesting an adequate immune response. Therapeutic interventions resulting in depletion of leukocytes to alleviate reperfusion injury might impair the immune response of those patients acquiring perioperative infection and should be approached with caution. Leukocyte depletion maybe effective in patients for whom an extended period of CPB was required. Further investigations to prove this hypothesis awaits confirmation.