Monocyte and neutrophil activity after minor surgical stress

BACKGROUND/PURPOSE: Surgical stress produces changes in the immune status of patients. In adults, major surgery causes immunosuppression, whereas minor operations stimulate immune responses. In children, the immunologic response to surgery has not been elucidated completely. The authors investigated the effects of minor surgery on immune response by analyzing neutrophil and monocyte phagocytosis and oxidative burst activity. METHODS: Sixteen children undergoing elective minor surgery were enrolled. Blood samples were collected before the operation (at time of induction of anesthesia), at the end of operation, and 72 hours after surgery. Neutrophil and monocyte phagocytosis and oxidative burst activity were studied using a flow cytometric method. RESULTS: Phagocytosis and oxidative burst increased significantly at the end of the operation, both in neutrophils (7.4% and 14.3%, respectively) and monocytes (11.6% and 27%, respectively). The increase was only significant for monocytes (17.5%) 72 hours after surgery. White cell count did not show any significant changes. There was no significant correlation between phagocytosis, oxidative burst activity, and white cell count or neutrophil and monocyte count. CONCLUSIONS: This study shows that minor surgery in children induces immune activation by increasing neutrophil and monocyte phagocytosis and oxidative burst activity. Further studies are required to understand the molecular basis of these findings.