Immunohistochemical study of carbohydrate antigen expression in gastric carcinoma.

The expression of carbohydrate antigens in malignant and non-malignant gastric mucosa was studied immunohistochemically using the monoclonal antibody AH6 directed to Ley antigen, FH2 directed to Lex antigen, and FH6 directed to sialyl-Lex antigen. Formalin-fixed gastric tissue resected from 54 patients with gastric cancer and 20 patients with gastric ulcer were tested. The incidence of positive cases in gastric cancer patients with each antibody was as follows: AH6;85%, FH2;74%, FH6;74%. The Lex antigen was expressed in 81.5% of cases histologically classified as undifferentiated type, and 66.7% of cases classified as differentiated type. It was expressed in a higher incidence in early stage cancer (93.3%) than in advanced stage cancer (66.7%). Sialyl-Lex antigen was detected in more cases of differentiated type (88.9%) than in those of undifferentiated type (59.3%), whereas none of 8 early cancers of undifferentiated type expressed the antigen. The incidence of the expression of Ley antigen did not differ in relation to histological type or invasiveness. Lex and Ley antigens were detected in noncancerous gastric epithelium. Sialyl-Lex antigen was not detected in the normal fundic gland region. These results demonstrate that Lex antigen may be a differentiation-associated antigen, and sialyl-Lex antigen might be useful as a marker of differentiated cancer and an indication for invasion of undifferentiated cancer.