In this study, soluble receptor of interleukin-2, interleukin-8, creatine kinase, and creatine kinase MB isoenzyme levels were determined serially before, during, and after cardiopulmonary bypass in blood samples of 24 patients. Interleukin-2 receptor levels were 683+/-80 U/ml in the preoperative period and 640 60 U/ml during hypothermia. Subsequently, these levels increased significantly at the end of the procedure (791+/-70 U/ml, P<0.01), remaining elevated I h after (1882+/-92 U/ml, P<0.001) and reaching peak values 24 h postoperatively (1,752+/-200 U/ml, P<0.001). Preoperative plasma values of interleukin-8 were 230 43 pg/ml. Interleukin-8 concentrations were 185+/-25 pg/ml during hypothermia. The peak interleukin-8 levels were observed at the end of cardiopulmonary bypass (754+/-94 pg/ml, P<0.001) and tended to decrease 1 h after the procedure (643+/-76 pg/ml, P<0.001), declining to preoperative values, 24 h postoperatively (273+/-41 pg/ml).