Preservation of immune response after laparoscopy.

We evaluated the immunologic responses following laparoscopic and open surgery by comparing delayed type hypersensitivity induration size before and after each method of accessing the abdominal cavity. One hundred and thirty-two male Sprague-Dawley rats were sensitized with keyhole limpet hemocyanine (KLH). Animals were challenged with KLH and phytohemaglutanin (PHA) 10 days after sensitization. On day 14 after initial sensitization animals were randomly divided into three groups. Group one served as controls and had no procedure performed, group two underwent peritoneal insufflation with carbon dioxide gas to a pressure of 6-8 mm Hg for one half hour, and rats in group three had a midline laparotomy which was closed after one half hour. Each rat was challenged with KLH immediately and at three days postoperatively. The area of induration in response to each of the challenges was measured with calipers 24 and 48 hours after the challenge. Results of this skin testing showed that the group of animals that underwent laparotomy, despite having normal responses preoperatively, had significantly diminished responses to both KLH and PHA when challenged postoperatively. The insufflated group showed no differences from control animals at any time point examined. We conclude that DTH response in this model is better preserved after laparoscopy than laparotomy. We further conclude that the defect in DTH response is in the effector arm. The question of the clinical significance of these findings is addressed.