THE ROLE OF NEUTROPHILS IN PERITONEAL ADHESION FORMATION

The most common cause of intraperitoneal adhesions is previous abdomin al surgery. Postoperative adhesion formation results from a fibroproli ferative inflammatory reaction that begins with an influx of polymorph onuclear leukocytes (PMNs) into the peritoneal cavity. Adherence of th e PMNs to the endothelial cells (EC) is necessary for PMN migration in to the tissue in response to a stimulus. Several receptor-counterrecep tor pairs of ligands such as GD11/CD18 on the PMN and ICAM-1 (CD54) on EC have been identified. Monoclonal antibody against CD11/CD18 (R15.7 ) inhibits PMN adherence and migration and consequently protects again st PMN-induced tissue injuries. We therefore studied the effect of pre venting PMN-EC adherence, using anti-CD18 monoclonal antibody, on post operative adhesion formation in rabbits. Group 1 was a control receivi ng physiologic saline, and group 2 received anti-CD18 antibody (R15.7, 2 mg/kg). The treatment was administered iv at the end of surgery and repeated on the first and second postoperative days. Peritoneal adhes ions were induced at laparotomy by repairing two peritoneal defects, b y oversewing the defect (model 1), and by resuturing the removed parie tal peritoneum in its place as an ischemic graft (model 2). Adhesions were evaluated blindly at 10 days after operation by measuring the per centage of the suture line covered with adhesions (model 1) or by a sc oring system (model 2). All control animals developed intraperitoneal adhesions and the percentage of the suture line covered with adhesions was 25 +/- 5.9% (mean +/- SEM) and the mean score in model 2 was 0.9 +/- 0.2. Anti-CD18 antibody, R15.7, increased the degree of postoperat ive adhesion formation in both models, but the results were significan t only in model 2. Also, anti-CD18 antibody significantly decreased pe ritoneal neutrophils from 11.1 x 10(7) +/- 1.8 x 10(7) to 2.2 x 10(7) +/- 0.4 x 10(7) (P < 0.001) on the first postoperative day. It is conc luded that inhibition of PMN-EC adherence does influence the postopera tive adhesion formation. These results might suggest that PMNs have a role in modulating postoperative adhesion formation. (C) 1996 Academic Press, Inc.