The expression of Lewis antigens in neoplasms of the gastrointestinal tract

The indirect immunoperoxidase technique has been used to demonstrate Lea and Leb antigens in paraffin sections of both morphologically normal gastric and colonic mucosae and their neoplastic counterparts. Expression differed in various regions of the gastrointestinal tract: Leb occurred most frequently in the stomach and Lea most frequently in the colon. Coexpression of Lea and Leb occurred in only 5% of cases of normal mucosa, in 65% of gastric carcinomas and in 82% of carcinomas of the colon. Furthermore, 75% of cases of intestinal metaplasia in gastric mucosa and 30% of tubular adenomas, 50% of villous adenomas and 70% of tubulovillous adenomas in the colon co-expressed Lea and Leb antigens. In this study, the expression of Lewis antigens in carcinoma was found to differ from that of adjacent normal mucosa in 95% of cases of gastric carcinoma and 100% of cases of colonic carcinoma. The differences were shown by antigen acquisition and/or deletion. Similar changes were shown in 88% of cases of intestinal metaplasia in gastric mucosa, 20% of cases of tubular adenomas and 57% of cases of villous and tubulovillous adenomas of colon.