Immunochemical and immunohistological expression of Lewis histo-blood group antigens in small intestine including individuals of the Le(a+b+) and Le(a?b?) nonsecretor phenotypes

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Abstract
Histological samples and total non-acid glycosphingolipids were prepared from small intestine of human cadavers with the Le(a+b+) and Le(a−b−) nonsecretor phenotypes and contrasted with the more common Lewis phenotypes. Glycolipid fractions were analysed by thin-layer chromatography and tested for Lewis activity with monoclonal antibodies reactive to Lewis epitopes. Paraffin-embedded small intestine sections were also fluorescently immunostained with anti-Lewis antibodies. Unlike the common Lewis positive phenotypes, we were immunochemically able to demonstrate the copresence of large amounts of Lea and Leb glycolipids in the Le(a+b+) sample. In addition we demonstrated increased formation of extended Lewis structures in this phenotype. By immunohistochemistry Lea, Leb and type 1 precursor chain epitopes could be demonstrated in the brush border. These results show that the expression of the Le(a+b+) phenotype at the erythrocyte phenotyping level parallels the small intestinal expression of this phenotype, and the patterns of Lewis antigen expressions are unique to this phenotype. By immunohistochemistry and immunochemistry we also demonstrated the presence of trace amounts of Lewis active glycoconjugates in the small intestine of the Le(a−b−) nonsecretor and Le(a+b−) samples. In the Le(a−b−) nonsecretor Lea and Leb activity was absent and type 1 precursor was present in brush border, while Leb activity was immunohistologically demonstrated in the Golgi apparatus of the deep glands. Trace amounts of both Lea and Leb glycolipids were identified in this sample. In parallel trace Leb activity could also be detected in the glycolipids of the Le(a+b−) sample and could be immunohistologically demonstrated to be fully expressed in occasional cells in the deep glands of the small intestine, a pattern quite dissimilar to that of the Le(a−b−) nonsecretor. The results in this paper show that the expression of Lewis glycoconjugates in the small intestine parallel the expression of Lewis erythrocyte phenotypes. However, inappropriate Lewis activity is also seen in individuals of other phenotypes and the mechanisms by which these Lewis antigens are made appears to be different for different phenotypes.