title: Lymphocyte proliferation in mice after a full laparotomy is the same whether performed in a sealed carbon dioxide chamber or in room air.
abstract: OBJECTIVE
  Our laboratory has demonstrated that significantly more cell-mediated immunosuppression occurs after full laparotomy than after either anesthesia control or carbon dioxide (CO2) pneumoperitoneum. We further demonstrated that the postoperative immunosuppression is related to the length of the incision. Other investigators believe that the immunosuppression observed after laparotomy is caused by peritoneal exposure to small amounts of lipopolysaccharide found in circulating air. They believe that the better-preserved immune function associated with laparoscopic surgery results from the avoidance of air contamination of the peritoneal cavity. To investigate this hypothesis, we determined and compared postoperative lymphocyte proliferation rates after (a) laparotomy in room air, (b) laparotomy in a CO2 chamber, (c) CO2 insufflation in a murine model, and (d) anesthesia alone.
  
  
  METHODS
  Female C3H/He mice (n = 21) were divided randomly into four groups: (a) anesthesia control, (b) air laparotomy, (c) CO2 laparotomy, and (d) CO2 insufflation. The control mice underwent no procedure. The group 2 animals underwent a full midline incision (xiphoid to pubis) and exposure to room air for 20 min and then were clipped closed. The group 3 mice underwent a full midline incision in a sealed CO2 chamber for 20 min, and the group 4 mice insufflation with CO2 gas at 4 to 6 mm Hg for 20 min. Splenocytes were harvested from all the animals on day 2 after the interventions. Lymphocyte proliferation then was assessed using the nonradioactive colorimetric MTS/PMS system 72 h after concanavalin-A stimulation.
  
  
  RESULTS
  There was no significant difference in lymphocyte proliferation between the air and CO2 laparotomy groups. Lymphocyte proliferation in the anesthesia control and CO2 insufflation groups was significantly higher than in both the air laparotomy (p<0.05) and CO2 laparotomy (p<0.05) groups (p values by Tukey-Kramer test). There was no significant difference between the anesthesia control and CO2 pneumoperitoneum groups.
  
  
  CONCLUSIONS
  Our results suggest that full laparotomy performed in a sealed CO2 chamber compared to room air laparotomy resulted in similar suppression of lymphocyte proliferation. Furthermore, no significant suppression of lymphocyte proliferation was observed in the CO2 pneumoperitoneum group. These results, with regard to lymphocyte proliferation rates, refute the hypothesis that postoperative immunosuppression is related to air exposure and support the alternative hypothesis that immunosuppression is related to incision length.
authors.affiliation: Department of Surgery, Columbia-Presbyterian Medical Center, New York, NY 10032, USA.
authors.forename: S W
authors.initials: SW
authors.lastname: Lee
authors.forename: J C
authors.initials: JC
authors.lastname: Southall
authors.forename: N R
authors.initials: NR
authors.lastname: Gleason
authors.forename: E H
authors.initials: EH
authors.lastname: Huang
authors.forename: M
authors.initials: M
authors.lastname: Bessler
authors.forename: R L
authors.initials: RL
authors.lastname: Whelan
mesh_terms: D000388:Air; D000818:Animals; D002245:Carbon Dioxide; D002455:Cell Division; D005260:Female; D007108:Immune Tolerance; D007111:Immunity, Cellular; D007813:Laparotomy / Q000379:methods*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D011028:Pneumoperitoneum, Artificial / Q000379:methods*
chemical_list: D002245:Carbon Dioxide