[Biochemical basis of the ABO system subgroups].

This review article offers a survey of the biochemical and molecular biological basis of the ABO subgroups. In contrast to protein-based blood groups, the antigens of the ABO system are carbohydrate antigens. The determinant carbohydrate structures are synthesised stepwise by the action of glycosyltransferases which transfer single monosaccharide residues onto an appropriate precursor substance.

Evidence for erythrocyte membrane glycoproteins being carriers of blood-group P1 determinants.

The contribution of different membrane constituents to the bloodgroup P1 activity of human erythrocytes was investigated. Pronase digestion of native red cell stroma or partition between butanol and water had no serologically detectable effect, whereas pronase-treatment of previously butanol-extracted membranes liberated virtually all blood-group P1 determinants from the ghosts. On Laemmli gels, all P1 activity was found in the band 4.

Studies on blood-groups A1 and A2. Further evidence for the predominant influence of quantitative differences in the number of A antigenic sites present on A1 and A2 erythrocytes.

Blood-group O and A2 erythrocytes were treated with the A1-gene-dependent and A2-gene-dependent N-acetylgalactosaminyl transferases in the present of UDP-N-acetyl[14C]galactosamine. Although the transfer of N-acetyl[14C]galactosamine with A2 transferase was slower than with A1 enzyme, group O as well as A2 cells became agglutinable by anti-A1 reagents when incubated with both transferases. Fractionation of the labelled erythrocyte stroma into glycoprotein and glycolipid components showed an approximately equal distribution pattern of radioactivity in all experiments.

Immunochemistry of the Lewis blood-group system. III. Studies on the molecular basis of the Lex property.

The antigen specificities of different 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 found to be considerably smaller, comprising merely the structure Fuc alpha leads to 4GlcNAc--R. Based on this property, homogeneously recting Lex antibodies could be isolated from heterogeneous anti-Lea + b + x sera by means of affinity chromatography of Fuc alpha leads to 4GlcNAc-Synsorb.