IMMUNOHISTOCHEMICAL STUDY OF TISSUE FACTOR EXPRESSION IN NORMAL INTESTINE AND IDIOPATHIC INFLAMMATORY BOWEL-DISEASE

Aim-To investigate the localisation of tissue factor expression in nor mal and inflamed intestine. Methods-Serial cryostat sections of tissue taken from patients with Crohn's disease (n = 8), ulcerative colitis (n = 5), and from controls (n = 5) were stained with haematoxylin and eosin and immunostained for tissue factor, collagen type IV, fibrinoge n and platelet glycoprotein IIIa. Results-In control tissues tissue fa ctor was present as a continuous layer along the epithelial basal lami na: sections from controls did not immunostain for fibrinogen or plate lets. In non-ulcerated inflamed mucosa, tissue factor staining intensi fied in cases of Crohn's disease and was associated with fibrin deposi tion. Staining for tissue factor was either patchy or absent in cases of ulcerative colitis and there was no fibrin deposition. This change accompanied the early destruction of the epithelial basal lamina in ul cerative colitis that was not seen in Crohn's disease. In both disease s tissue factor expression in severely inflamed and ulcerated mucosa w as present on lamina propria macropages and vascular endothelium and w as associated with fibrin or platelet thrombi. In three of eight cases of Crohn's disease tissue factor expression and thrombi were evident in areas of submucosal vasculitis. These were not seen in adjacent nor mal vessels. Conclusions-These observations are consistent with a tiss ue factor haemostatic barrier in the intestine: this barrier seems to be incomplete or defective in ulcerative colitis. Tissue factor expres sion by macrophages and endothelial cells may be important, particular ly in the microvascular thrombosis and induration which are characteri stic of Crohn's disease.