Objective: To investigate in detail the immunohistochemical properties of the two endothelial-specific markers 1F10 (continuous endothelia) and MS-1 (discontinuous endothelia) in bowel tissues of patients suffering from chronic inflammatory bowel disease (IBD).
Method: Immunohistochemical techniques were employed to study the morphology and phenotypic expression of these two proteins in routinely processed bowel tissues from 27 patients with Crohn's disease, 18 patients with ulcerative colitis, and 20 normal controls.
Results: All patients with IBD and controls showed a low to moderate 1F10 immunohistochemical staining restricted to the lamina propria and submucosa. In contrast to ulcerative colitis patients and healthy controls, 1F10 immunoreactivity was strongly upregulated in the muscularis propria of the small and large bowel in Crohn's disease patients regardless of the histological severity of the inflammatory process. We did not observe immunoreactivity for MS-1 on endothelial surfaces in either Crohn's disease or ulcerative colitis.
Conclusions: We conclude that endothelia in patients with IBD do not undergo metaplasia. The high immunoreactivity of 1F10 antigen in the muscularis propria in Crohn's disease indicates a state of tropical immunological activation and may be important in the maintenance of chronic inflammation by facilitating leukocyte migration into sites of Crohn's disease involvement. Further studies of the factors controlling endothelial cell differentiation in the bowel of Crohn's disease patients may help to explain the features observed in this study.