DETECTION OF COMPLEMENT C3 AND FACTOR B-GENE-EXPRESSION IN NORMAL COLORECTAL MUCOSA, ADENOMAS AND CARCINOMAS

Local secretion of complement components in the human intestine has be en previously reported. However, the cellular source has not been iden tified. In this study, we demonstrate complement C3 and factor B mRNA expression in the normal colonic mucosa by irt situ hybridization anal ysis. C3 and factor B genes were found to be expressed at high levels in the epithelial cells of the lower parts of the crypts in colonic mu cosa, and this expression decreased gradually from the crypt base to t he luminal surface. At the upper crypt and the luminal surface, these genes almost disappeared. C3 and factor B genes were expressed in all crypts at the same level. Furthermore, C3 and factor B gene expression was also identified in adenomas and carcinomas. In these neoplastic t issues, C3 and factor B genes were expressed uniformly, and the polari zed distribution observed in the normal crypts was not detected. It is likely that complement components are locally synthesized in the inte stine, and that these complement components may actively participate i n normal immune and inflammatory responses over the enormous surface a rea of the intestinal mucosa.