[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.

[Enzymatic investigations on the basis of the subgroups A1 and A2. (author's transl)].

Human O and A2 erythrocytes were incubated with the alpha-N-acetyl-galactosaminyltransferases isolated from the plasma of A1 and A2 individuals in the presence of labelled UDP-N-acetylgalactosamine. It could be shown that both O and A2 cells could be agglutinated by anti-A1 reagent when treated with the A2 transferase. Furthermore, the incorporated radioactivity was about equal for both cell types, corresponding to about 600.

[Structure and biochemistry of blood group antigens].

On the basis of the structure of the most important determinants of the blood-group ABO(H) and Lewis systems as well as the mode of their biosynthesis it is discussed to what extent investigations on the distribution of the respective gene-dependent glycosyltransferases are able to contribute to a better understanding of the occurrence of various blood-group phaenotypes.

Blood group ABH antigens on human cord red cells. Number of H antigenic sites and their distribution among different classes of membrane constituents.

When the blood group H sites of cord erythrocytes obtained from newborn infants of groups O, A, B and AB were labelled specifically by incubation of the whole cells with the A1 gene dependent alpha-N-acetylgalactosaminyl transferase in the presence of UDP-N-acetyl [14C]-galactosamine, the incorporation of radioactivity was considerably lower than that found for cells from adults. Based on the amount of label recovered in the membranes, average values of 326,000 H sites per single O cell and 68,000 H sites per single A, B and AB cell were calculated. Following fractionation of the stromal blood group substances thus labelled, it was found that, on the average, 66% of the radioactivity was bound to glycoprotein material, 2.

Blood-group-ABH antigens of human erythrocytes. Quantitative studies on the distribution of H antigenic sites among different classes of membrane components.

The contribution of blood-group-active glycolipids and glycoproteins to the blood-group-ABH character of human erythrocytes was investigated. For that purpose the blood-group-H sites of human O cells were converted in vitro into group-A sites by transfer of alpha-N-acetyl-D-[14C]galactosamine residues with the aid of the blood-group-A gene-dependent alpha-N-acetylgalactosaminyl transferase prepared from human A1 plasma. Upon partition of the red cell membranes between water and organic solvent, about 5% of the label was found in the organic phase and about 20% in the water phase, thus reflecting the distribution of blood-group antigenic sites between glycosphingolipids with short carbohydrate chains and polyglycosylceramides, respectively.

Biosynthesis of a blood-group-I determinant reacting with anti-I Ma serum (group 1).

A blood-group-I determinant reacting specifically with anti-I Ma serum (group 1) has been produced biosynthetically by the action of a beta-galactosyl transferase isolated from human milk on a precursor glycoprotein produced by formic acid hydrolysis and beta-D-galactosidase action on blood-group H substance prepared from hog gastric mucosa.

Probable biosynthetic pathway for the synthesis of the B antigen for Bh variants.

Red cells and serum from two Bh variants (B+H-cells) have been investigated for B and H blood group glycosyltransferases. The H enzyme could not be detected using either type 1 or type 2 chain acceptors. The B enzyme was present in normal amount when 2'-fucosyllactose was used as substrate, neither 6'-fucosyllactose nor 6'-fucosyllactosamine could act as acceptors for the B enzyme.

Localization of blood-group A and I antigenic sites on inside-out and rightside-out human erythrocyte membrane vesicles.

Investigations of the fixation of 125I-labelled anti-A and anti-I antibodies onto rightside-out and inside-out membrane vesicles prepared from human A1 and OI erythrocytes, respectively, showed that both antibodies were bound to the rightside-out vesicles, giving clear evidence that blood group A and I antigenic sites are exclusively localized on the external surface of the membrane.

Blood-group A and G specific structures in toad (Bufo) spawn. Comparative studies on three species (Bufo bufo, Bufo viridis, Bufo calamita).

Permethylation analyses of the spawn material of three toad (Bufo) species allow the conclusion that the serologically determinant group in Bufo bufo spawn is identical with that found in human and hog blood-group A substances (i.e. GalNAc(alpha1,3) [Fuc(alpha1,2)] Gal -), and the serologically determinant group in Bufo viridis and Bufo calamita spawn is identical with that found in blood-group H substances (i.

Immunochemical investigations on water frog eggs: comparative studies on Rana ridibunda, Rana lessonae and their hybrid Rana esculenta.

Eggs of Rana ridibunda, Rana lessonae and their hybrid Rana esculenta were examined for their immunochemical properties. The reaction spectra obtained confirm the hybrid origin of Rana esculenta.

Hemagglutinins in female fish gonads: comparative investigations on perch (Perca fluviatilis) gonads of different stages of development.

Female gonads of the perch (Perca fluviatilis) in various stages of development are tested for hemagglutinin activity against human erythrocytes. Based on the different agglutination patterns obtained, and on inhibition tests with L-fucose and a mature gonad of a male perch, the appearance two different agglutinins in the course of the development of the female gonad is assumed.

Enzymatic synthesis of blood-group Lewis-specific glycolipids.

A blood-group Lewis precursor glycolipid was isolated from the plasma of a Lewis-negative individual [Le(a--b--)] and treated with fucosyltransferases from human gastric mucosa and GDP-fucose. Subsequently the glycolipid was adsorbed onto Le(a--b--) erythrocytes and the presence of blood-group Lewis antigens was assessed by passive hemagglutination with anti-Lewis sera. It was shown that the precursor glycolipid was enzymatically transformed to blood-group Lewis a (Lea) and Lewis b (Leb) specific glycolipids.

Immunochemical investigations on toad (Bufo) eggs: comparative studies on three species (B. bufo, B. viridis, B. calamita).

Eggs of three Bufo species (B. bufo, B. viridis and B.

Action of glycosyl transferases upon "Bombay" (Oh) erythrocytes. Conversion to cells showing blood-group H and A specificities.

Individuals of the rare "Bombay" (Oh) blood-group phenotype lacking, due to a genetic defect, the alpha(1-2)fucosyl transferase, which is responsible for converting blood-group H precursor substances to H-specific structures. Treatment with GDP-fucose and alpha(1-2)fucosyl transferase prepared from gastric mucosa of O individuals to transform native or ficin-treated "Bombay" erythrocytes into cells phenotypically resembling O cells. The transformation was achieved, however, after prior incubation of the "Bombay" erythrocytes with neuraminidase, indicating that blood-group H precursor molecules on the surface of these cells are masked by sialyl residues.