Peripheral blood lymphocyte changes after benign gastrointestinal surgery. Role of thymostimulin in reversing the postoperative immunodepression seen in humans.

A generalized state of immunosuppression during surgery has been implicated in the development of septic complications postoperatively. We studied 18 patients operated upon for benign diseases, to examine the influence of surgical trauma on circulating lymphocyte subpopulations in man. Additionally, we evaluated the effect of thymostimulin on these changes, in another group of 10 patients. Our results suggest that the total number of lymphocytes, as well as lymphocyte subpopulations CD3+ and CD4+, fell significantly following surgery. This reduction in cell number is more pronounced on the helper/inducer lymphocytes. The CD4+/CD8+ ratio decreases significantly after operation. For patients with no complications, the immunosuppression in terms of peripheral lymphocyte population, seen in the postoperative period is usually reversible around the seventh day. On the other hand, peripheral blood lymphocyte changes in the postoperative period were less pronounced in patients treated with thymostimulin. Thymostimulin's action is predominantly on T lymphocytes, and within these, on the T helper/-inducer subpopulation. And finally, thymostimulin is capable of maintaining a normal relationship between helper/inducer and suppressor/cytotoxic cells (CD4+/CD8+ ratio) during the postoperative period, suggesting a better immune state.