MONOCLONAL-ANTIBODY 1F10 IMMUNOREACTIVITY IN INFLAMMATORY BOWEL-DISEASE - A NEW MARKER SPECIFIC ONLY FOR CONTINUOUS ENDOTHELIAL-CELLS

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 suffe ring from chronic inflammatory bowel disease (IBD). Method: Immunohist ochemical techniques were employed to study the morphology and phenoty pic expression of these two proteins in routinely processed bower tiss ues from 27 patients with Crohn's disease, 18 patients with ulcerative colitis, and 20 normal controls. Results: All patients with IBD and c ontrols showed a low to moderate 1F10 immunohistochemical staining res tricted to the lamina propria and submucosa. In contrast to ulcerative colitis patients and healthy controls, 1F10 immunoreactivity was stro ngly upregulated in the muscularis propria of the small and large bowe r in Crohn's disease patients regardless of the histological severity of the inflammatory process. We did not observe immunoreactivity for M S-1 on endothelial surfaces in either Crohn's disease or ulcerative co litis. Conclusions: We conclude that endothelia in patients with IBD d o not undergo metaplasia. The high immunoreactivity of 1F10 antigen in the muscularis propria in Crohn's disease indicates a state of topica l 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 controlli ng endothelial cell differentiation in the bowel of Crohn's disease pa tients may help to explain the features observed in this study.