Enhanced responsiveness of circulatory neutrophils after cardiopulmonary bypass: Increased aggregability and superoxide producing capacity

Cardiac surgery with cardiopulmonary bypass (CPB) induces a whole body infl ammatory response that sometimes leads to postoperative organ dysfunction, and neutrophil activation plays an important role in this reaction. Neutrop hil priming has been described as a change in neutrophil status such that n eutrophils show enhanced responsiveness to a second activating stimulus. We hypothesized that neutrophil priming occurs by cardiac surgery with CPB an d is temporally related to the neutrophilia after surgery. To evaluate prim ed circulatory neutrophil status, we measured aggregation activity stimulat ed by N-formyl-methyl-leucyl-phenyl-alanine (FMLP) and free radical produci ng activity by tumor necrosing factor (TNF) a in peripheral blood samples. Eleven adult patients undergoing elective cardiac surgery with CPB were stu died. Blood samples were taken before surgery, at the end of bypass, 12 h a fter surgery, and 7 days after surgery. Aggregation activity and superoxide generation were significantly elevated 12 h after surgery when compared to presurgery values, indicating that cardiac surgery is associated with circ ulatory neutrophil priming. The number of neutrophils markedly increased at the end of cardiopulmonary bypass and reached a peak 12 h after surgery. T he circulatory neutrophils of cardiac surgical patients become primed after surgery, coincident with the peak neutrophil count. These results suggest that circulatory neutrophils after cardiac surgery with CPB have enhanced r esponsiveness and are predisposed to systemic inflammation.