Immunologic Effects of Hand-assisted Surgery on Peritoneal Macrophages: Comparison to Open and Standard Laparoscopic Approaches

Background: Exaggerated activation of peritoneal immunity after major abdominal surgery activates peritoneal macrophages (PMs), which may lead to a relative local immunosuppression. Although laparoscopy (L) is known to elicit a smaller attenuation of peritoneal host defenses, compared with open (O) surgery, effects of the hand-assisted (HA) approach have not been investigated to date.

Methods: Eighteen pigs underwent a transabdominal nephrectomy via O, HA, or L approach. PMs were harvested at 4, 12, and 24 hours through an intraperitoneal drain and stimulated in vitro with lipopolysaccharide. The production of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) by the purified macrophage cultures was measured with the use of a standard enzyme-linked immunosorbent assay technique. Statistical comparison was performed by using analysis of variance and Student t test.

Results: In vitro lipopolysaccharide-induced IL-6 and TNF-alpha production by PMs increased over the 24-hour period in all 3 groups. Stimulated PMs harvested at 12 and 24 hours postoperatively secreted higher levels of IL-6 in the O group, compared with both the HA group (P = .02, P = .01) and L group (P = .04, P = .001). PMs harvested at 4, 12 and 24 hours postoperatively also produced more TNF-alpha in O group, compared with both the HA group (P = .03, P = .03, and P = .01) and L group (P = .01, P = .05 and P = .03). There was no significant difference between H and L groups in production of either cytokine.

Conclusions: Abdominal surgery attenuates peritoneal host defenses regardless of the surgical approach employed. However, for the first time, we demonstrated that the HA approach, similar to laparoscopy, is superior to open surgery in the degree of PM activation. Overall, in addition to clinical benefits of minimal access, HA surgery may confer an immunologic advantage over laparotomy.