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.