Location of tumour necrosis factor a by immunohistochemistry in chronic inflammatory bowel disease

This study determined the location and tissue density of cells immunoreactive for tumour necrosis factor a (TNF a) in intestinal specimens from 24 patients with chronic inflammatory bowel disease (15 with Crohn's disease, nine with ulcerative colitis) and 11 controls. There was significantly increased density of TNF a immunoreactive cells in the lamina propria of both ulcerative colitis and Crohn's disease specimens, although the distribution of these cells differed in the two conditions. In ulcerative colitis most of the TNF a immunoreactivity was seen in the subepithelial macrophages, with comparatively less in the deep lamina propria, while in Crohn's disease immunoreactive cells were distributed evenly throughout the lamina propria. Increased submucosal immunoreactivity was found only in Crohn's disease, in which TNF a positive macrophages tended to cluster around arterioles and venules, often infiltrating and disrupting vascular endothelium. It is suggested that this degree of TNF a production probably contributes significantly to the pathogenesis of both Crohn's disease and ulcerative colitis, by impairing the integrity of epithelial and endothelial membranes, increasing inflammatory cell recruitment, and by prothrombotic effects on the vascular endothelium. (Gut 1993; 34: 1705-1709) clinical benefit, and it is therefore important that the extent of local production is assessed more directly. In this study we have used immunohistochemistry to determine the distribution and density ofTNF a containing cells, in the mucosa and submucosa of patients with chronic inflammatory bowel disease.