[Influence of cardiopulmonary bypass on lymphocyte function].

It is known that lymphocyte function is impaired after cardiopulmonary bypass (CPB). In this study, the lymphocyte stimulation test (LST) with PHA was used before and after CPB in 28 adult patients, and compared with the surgical parameters and serum cytokine (IL-6, IL-8) levels. LST was impaired after CPB in all patients. Although this value usually recovered by the third postoperative day (POD); (normal group, n = 16), some patients showed prolonged duration of the impaired LST (delayed group, n = 12). Therefore, the parameters of surgery, white blood cell (WBC) count, lymphocytes and subsets, and serum cytokine levels were compared between the normal and the delayed groups. There was no significant difference in the number of WBCs or lymphocytes between these two groups. OKT4-positive cells were reduced on the first POD in both groups, and in the normal group, the number of OKT4-positive cells recovered more quickly than in the delayed group. Serum IL-6 and IL-8 levels in the delayed group were elevated after CPB, and were significantly higher in the delayed group than in the normal group. In conclusion, patients who showed prolonged impairment of lymphocyte function may be partly due to prolonged CPB.