Immunochemistry of the Lewis Blood-Group System

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Abstract
The antigen specificities of different [human] anti-Lex sera were examined by immunoadsorption studies using adsorbents with well-defined carbohydrate units covalently bound to an inorganic matrix (Synsorb, Chembiomed). In contrast to those of normal anti-Lea and anti-Leb sera, the antibody binding site of Lex antibodies was considerably smaller, comprising merely the structure Fuc.alpha.1.fwdarw.4GlcNAc-R. Based on this property, homogeneously reacting Lex antibodies were isolated from heterogeneous anti-Lea+b+x+ sera by affinity chromatography on Fuc.alpha.1.fwdarw.4GlcNAc-Synsorb. The serological reactivity of the purified Lex antibodies against a Lea-active glycolipid isolated from human plasma was compared with that of normal anti-Lea serum using hemagglutination inhibition and quantitative passive hemagglutination tests, indicating that the cord blood erythrocyte Lex character is not based on the existence of a separate Lex antigen, but on the ability of the anti-Lex antibodies to react already with traces of Lea substance present on fetal erythrocytes, not detectable by normal anti-Lex agglutinins.
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