"Post perfusion syndrome" after cardiopulmonary bypass (CPB) has been known to be evoked by inflammatory reactions. To elucidate the effect of perfusate temperature during CPB on subsequent inflammatory reactions, serum levels of interleukin (IL)-6, IL-8, tumor necrosis factor-alpha, IL-1 beta, and polymorphonuclear (PMN) elastase were measured before and after (0, 12 hours, and 24 hours after) CPB in adult patients undergoing cardiac operations. Patients were divided into two groups: the normothermic CPB group (NOR, 34 degrees C perfusate temperature, n = 8) and hypothermic CPB group (HYP, 28 degrees C perfusate temperature, n = 8). In both groups, IL-6, IL-8, and PMN elastase levels were elevated during CPB, while the increase of tumor necrosis factor-alpha and IL-1 beta was not detected. The increase in IL-8 and PMN elastase levels at 12 hours after CPB was significantly less in NOR than in HYP (IL-8; NOR versus HYP, 15.1 +/- 12.9 versus 62.5 +/- 30.6 pg/ml, p < 0.05, PMN elastase; 394 +/- 200 versus 1085 +/- 523 micrograms/L, p < 0.05) while neither group showed any difference in IL-8 and PMN elastase at 24 hours after CPB. There was no difference in IL-6 between the two groups, and no significant increase in tumor necrosis factor-alpha and IL-1 beta levels were detected in either group after CPB. These results demonstrate that although CPB activated inflammatory reactions detected by IL-8 and PMN elastase activity, post operative persistence of these reactions were attenuated by warm CPB.