Advantages of laparoscopic compared to conventional surgery are not related to an innate immune response of peritoneal immune activation: an animal study in rats.

Purpose: Laparoscopic surgery (LS) has proved superior compared to conventional surgery (CS) regarding morbidity, length of hospital stay, rate of wound infection and time until recovery. An improved preservation of the postoperative immune function is assumed to contribute to these benefits though the role of the local peritoneal immune response is still poorly understood. Our study investigates the peritoneal immune response subsequent to abdominal surgery and compares it between laparoscopic and conventional surgery to find an immunological explanation for the clinically proven benefits of LS.

Methods: Wistar rats (N = 140) underwent laparoscopic cecum resection (LCR; N = 28), conventional cecum resection (CCR; N = 28), laparoscopic sham operation (LSO; N = 28), conventional sham operation (CSO; N = 28), or no surgical treatment (CTRL; N = 28). Postoperatively, peritoneal lavages were performed, leukocytes isolated and analyzed regarding immune function and phagocytosis activity.

Results: Immune function was inhibited postoperatively in animals undergoing LCR or CCR compared to CTRL reflected by a lower TNF-α (CTRL 3956.65 pg/ml, LCR 2018.48 pg/ml (p = 0.023), CCR 2793.78 pg/ml (n.s.)) and IL-6 secretion (CTRL 625.84 pg/ml, LCR 142.84 pg/ml (p = 0.009), CCR 169.53 pg/ml (p = 0.01)). Phagocytosis was not affected in rats undergoing any kind of surgery compared to CTRL. Neither cytokine secretion nor phagocytosis activity differed significantly between laparoscopic and conventional surgery.

Conclusions: According to our findings the benefits associated with LS compared to CS cannot be explained by differences in the postoperative peritoneal innate immune response. Further studies are needed to elucidate the causes for a more favorable postoperative outcome in patients after LS compared to CS.