• Top
• Objectives
• Methods
• Results
• Conclusions

Objectives

Surgical trauma has been reported to be associated with an elevated apoptotic rate of circulating leukocytes. However, the effect of cardiac surgery on leukocyte apoptosis has not yet been investigated. Our study was therefore designed to address this question.

Methods

Flow-cytometric immunophenotype data from 70 children (age 3–16 years) who underwent cardiac surgery with (n = 50) or without (n = 20) cardiopulmonary bypass (CPB) were analyzed for T-cell apoptosis, based on light scatter and surface antigen (CD45/CD3) expression. Additionally, in vitro isolated leukocytes from healthy volunteers were incubated with serum obtained from cardiac surgery patients before, during and after surgery. Apoptosis was detected by flow cytometry after staining with annexin V and DNA condensation by laser scanning cytometry. Serum cytokine and troponin I levels were also determined.

Results

Patients undergoing CPB had elevated lymphocyte apoptosis. In particular, T-cell apoptosis increased from 0.45% (baseline) to 1.34% (4 hours postoperative; analysis of variance P = 0.0034). No effect was found during and after surgery without CPB. These results were in accordance with in vitro findings demonstrating elevated apoptotic activity for lymphocytes and neutrophils in the serum from patients with CPB at reperfusion and up to 3 days after surgery (P < 0.01). No such activity was found in patients operated on without CPB. The increase in apoptosis correlated well with the increase in troponin I and IL-10 levels.

Conclusions

At present, the agents that induce apoptosis during CPB surgery are not well identified. However, IL-10 might be involved in peri- and postoperative neutrophil apoptosis. Increased apoptosis of circulating lymphocytes and neutrophils further contributes to the immune suppressive response to surgery with CPB, for example by inactivating phagocytes by uptake of apoptotic cells (e.g. via CD36) or removal of activated cells. Elevated apoptotic activity in the blood of patients during CPB might also contribute to the destruction of cardiomyocytes during and after pediatric cardiac surgery.

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