Serological and biochemical studies on En(a-) human erythrocytes in a Japanese family

The propositus erythrocytes with phenotype En(a-), which was found in the first example of a Japanese family, reacted with anti-N serum weaker than the ordinary phenotype N erythrocytes. When the erythrocyte membranes of the propositus were subjected to SDS-PAGE, no glycophorin A was observed on the gel by PAS staining, whereas glycophorin B band was observed. The S and the s antigens of the propositus erythrocytes were appeared to be normal. These results suggested that N activity of the propositus erythrocytes may be derived from glycophorin B components on the erythrocyte membranes. The amounts of bound sialic acid of the erythrocyte membranes were significantly lower in the En(a-) erythrocytes than the ordinary OMN erythrocytes. Neither the OMN nor the En(a-) erythrocytes showed the agglutinability to Arachis hypogaea lectin. The number of lectin receptor sites on the En(a-) erythrocyte membranes was significantly lower than on the OMN erythrocyte membranes for Limulus polyphemus, Triticum vurgaris and Bauhinia purpurea lectins. These results provide further support for the contention that En(a-) cells lack the glycophorin A as major erythrocytes sialoglycoprotein on the membranes.