Effects of laparotomy, and carbon dioxide and air pneumoperitoneum, on cellular immunity and peritoneal host defences in rats

Objective: To assess the effects of laparotomy, and insufflation of carbon dioxide and air, on the immune system in rats. Design: Randomised laboratory study. Setting: Teaching hospital, Turkey. Animals: 77 Wistar rats randomly allocated to 2 groups one of which was sen sitised with dinitrofluorobenzene (DNFB, n = 43) and one of which was not ( n = 34). Interventions: The DNFB group was sensitised and subdivided into control (n = 8), laparotomy alone (n = 7), and insufflation with carbon dioxide (CO2) for 30 and 60 mins (n = 7 in each) or room air for 30 and 60 mins (n = 7 i n each). A week later DNFB was reapplied to the ears. In the group not sens itised with DNFB the animals were subdivided similarly, the corresponding n umbers in each group being, 6, 6, 6, 6, 5, and 5. Main outcome measures: Delayed type hypersensitivity (DTH) measured by ear swelling in the DNFB group, and peritoneal bactericidal activity, total fre e peritoneal cell counts (TPC), and cell types in the non-sensitised group. Results: There were significant differences in the degree of ear swelling i n the DNFB group between control and laparotomy groups (p = 0.0001) and bet ween control and both insufflations of air (p = 0.002 and p = 0.0003, respe ctively). In the non-sensitised group peritoneal bactericidal activity was significantly increased after 7 hours in the 60 mins air insufflation group (p = 0.04). At 24 hours there were no differences among the groups. TPC we re not affected. The number of peritoneal polymorphonuclear leucocytes (PMN ) was significantly higher in the laparotomy alone group than in the contro l or any of the insufflation groups (p < 0.05). Conlusions: Laparotomy and air insufflation depressed cell-mediated immunit y. Peritoneal bactericidal activity was affected only after 60 minutes of a ir insufflation.