IS IMMUNE FUNCTION BETTER PRESERVED AFTER LAPAROSCOPIC VERSUS OPEN COLON RESECTION

The purpose of this preliminary study was to evaluate immunologic resp onses to laparoscopic vs standard open colon resection and to evaluate possible mediators of any differences found. Specifically, we compare d cortisol levels and delayed-type hypersensitivity response after eac h method of colon resection in a group of 20 pigs. Two groups of 10 an imals each were treated in identical fashion including bowel preparati on, anesthesia, and postoperative management. The only difference betw een groups was that one underwent laparoscopic and the other an open c olon resection. Blood specimens for cortisol were drawn before, during , and immediately postoperatively as well as at 11 A.M. on postoperati ve days 1 and 2. All animals had been previously immunized as piglets with Sow Bac-E (Oxford Veterinary, Worthington, MN), an antigen prepar ation of common pig pathogens. At the conclusion of the operative proc edure 0.5 cc of the antigen was injected intradermally on the right fo relimb of the animals. At 48 and 72 h postoperatively the largest diam eters of induration surrounding the injection site were measured and a veraged. Cortisol levels were measured in serum samples by radioimmuno assay (Met-Path, Rockville, MD). Statistical significance was determin ed by t-test. Results of skin antigen testing showed that the group of pigs that underwent laparoscopic resection had a 20% greater response , 1.54 cm +/- 0.28 cm at 48 h and 1.53 cm +/- 0.18 cm at 72 h. For the open-surgery group results were 1.24 cm +/- 0.26 cm at 48 h and 1.32 cm +/- 0.21 cm at 72 h, P < 0.05 for the difference between groups at both 48 and 72 h. Cortisol levels were not significantly different bet ween groups at any of the time points. We conclude that T-cell-related immune function in this model, as measured by delayed-type hypersensi tivity, is better preserved after laparoscopic than open colon resecti on. We further conclude that cortisol levels are not responsible for t he improved preservation of the immune response. The benefits of impro ved postoperative immune function may be significant for patients unde rgoing laparoscopic colon resection.