Expression of Lewis(a), Lewis(b), and sialated Lewis(a) antigens in early and advanced human gastric cancers.
An immunohistochemical analysis of the expression of Lewis(a), Lewis(b), and sialated Lewis(a) blood group antigens was performed on specimens of human non-involved stomach (n = 91), early gastric cancers (n = 41), and advanced gastric cancers (n = 50). In non-involved stomach, Lewis(a) and Lewis(b) were detected mainly in surface epithelium, although sialated Lewis(a) was scarcely expressed. These blood group-related antigens were rarely observed in deep glands. In gastric cancers, Lewis(a) showed a tendency to be expressed in well or moderately differentiated carcinomas, and this was observed to be more marked in advanced tumors. There was no obvious difference in positive ratios of Lewis(b) between degrees of differentiation of the cancers. Sialated Lewis(a) was not detected in early cancers, and its frequent expression in well- or moderately differentiated, advanced carcinomas suggested an association with both cancer differentiation and progression. These results indicate that knowledge of the expression of blood group antigens may help interpret the antigenic alterations occurring in the course of carcinogenesis, differentiation, and progression of gastric cancers.