Deposits of terminal complement complex (TCC) in muscularis mucosae and submucosal vessels in ulcerative colitis and Crohn's disease of the colon

Abstract

Extensively washed, ethanol fixed and paraffin embedded colonie specimens from 15 patients with ulcerative colitis (UC) and nine patients with Crohn's disease (CD) of the colon, ileal specimens from six patients with CD of the ileum, and histologically normal control specimens obtained from 10 patients operated for colonie carcinoma, were examined by immunohistochemistry with a monoclonal antibody specific for a neoepitope in the C9 part of the terminal complement complex (TCC). The submucosal blood vessels in inflammatory bowel disease (IBD) showed significantly more TCC positivity than the controls, and vascular TCC deposition was statistically related (p<0.001) to degree of inflammation. Five of the six ileal CD specimens contained likewise vascular TCC deposits. In addition, five UC specimens and one colonie CD specimen contained TCC-positive fibrils in the muscularis mucosae or submucosa. There was no significant difference in vascular TCC deposits between UC and CD. The results suggested that terminal complement activation takes place in the intestinal lesions of IBD.