Macrophage and T-lymphocyte infiltrates in human peritoneal adhesions indicate a chronic inflammatory disease.

Background: Peritoneal adhesions are common and lead to significant clinical morbidity and mortality. Besides various individual factors, notably the inflammatory response to peritoneal defects affects adhesion formation. The aim of this study was to investigate whether there is inflammatory activity even in persistent adhesions.

Methods: Tissue specimens of 40 patients suffering peritoneal adhesions were prospectively collected. Expression profiles of seven parameters as potential mediators in cellular immune response, cell differentiation, and wound healing were analyzed (macrophages [CD68], B-lymphocytes [CD20] and T-lymphocytes [CD45], cyclo-oxygenase-2 [COX-2], Notch-3, beta-catenin, and c-myc). Furthermore, clinical details and co-morbidities were recorded.

Results: Infiltrates of mononuclear round cells were found in all adhesion specimens irrespective of the maturity. Immunohistochemical analysis identified mononuclear round cells as macrophages (CD68) and as T-lymphocytes (CD45). Expression of CD68 was significantly elevated in adhesion tissue with an age<12 months. Positive expression of CD45, COX-2, Notch-3, beta-catenin, and c-myc, was observed even in long-lasting adhesions.

Conclusions: A persistent inflammatory process has to be considered, even in mature adhesions. Macrophages may play an important role in triggering adhesions, whereas T-cells and the Notch-3/beta-catenin complex signaling pathway may play a crucial role in maintaining adhesions. These findings indicate that adhesions should not be regarded simply as an adynamic result of an operative trauma but rather may be grasped as a permanent process in remodeled tissue.