Immunocolocalization of the heme oxygenase-2 and interstitial cells of Cajal in normal and aganglionic colon

Purpose: Interstitial cells of Cajal (ICCs) are pacemaker cells that play an important role in the control of gut motility. Carbon monoxide (CO) has been proposed as an endogenous messenger molecule between ICC and smooth muscle cells in the gastrointestinal tract (GIT). Heme oxygenase-2 (HO-2) is the main physiologic mechanism for generating CO in human cells. The aim of this study was to investigate the immunocolocalization of the HO-2 and ICCs in normal and aganglionic bowel of Hirschsprung's disease (HD). Methods: Full-thickness specimens were obtained from aganglionic colon during pull-through operation from 10 patients diagnosed as having HD. Normal control large bowel specimens were collected from 4 patients during bladder augmentation procedures. Double immunostaining was carried out using c- kit and HO-2 antibodies. Immunolocalization was detected by means of confocal laser scanning microscopy. Results: HO-2 immunoreactivity (IR) was found in many ICCs present around the myenteric plexus, within the longitudinal and circular muscle layers and at the innermost part of the circular muscle layer in normal colon. In the aganglionic colon there was absence of HO-2 IR in the sparsely found ICCs. In the transitional zone of HD bowel the colocalization of HO-2 IR and ICCs was much reduced compared with controls. Conclusions: The results of this study provide the first evidence for the presence of HO-2 immunoreactivity in the ICCs in normal human colon and absence of HO-2 immunoreactivity in sparsely appearing ICCs in the bowel of HD patients. The lack of HO-2 in the ICCs in the bowel of HD patients may result in impaired intracellular communication between ICCs and SMCs causing motility dysfunction. J Pediatr Surg 38:73-77. Copyright 2003, Elsevier Science (USA). All rights reserved.