[Effect of immune response during cardiopulmonary bypass on post-operative infections]

To study the effects of extracorporeal circulation on the post operative infections, the relationship between the influences of the immunologic change during cardiopulmonary bypass (CPB) and post operative change of neutrophilia was evaluated in 52 patients. These patients were divided into two groups: group A (non-infected), 19 patients whose neutrophil count increased within 15,000/microliters in peripheral blood after operation. Group B (infected), 33 patients whose neutrophil count increased 15,000/microliters or more within one week after operation. Immunoglobulins (IgG, IgA, IgM) and complement fraction (C3, C4, CH50) levels decreased significantly during CPB, but there was no significant difference between the two groups. The amount of lymphocyte subsets of helper/inducer T cell and suppressor/cytotoxic T cell showed similar change in both groups. On the contrary the amount of lymphocyte subset of Natural Killer cell showed significant increase in A group during CPB when compared with B group, suggesting immunological activation, however, in the group which showed less than 40% increase of NK cell during CPB, there was significant increase of neutrophils after operation compared with the other group which showed high increase of NK cell. These findings suggested the increased activation of the Natural Killer cell during CPB is a favorable response, especially for preventing infections after operation.