Immunochemistry of the Lewis-blood-group system: partial characterization of Le(a)-, Le(b)-, and H-type 1 (LedH)-blood-group active glycosphingolipids from human plasma

Human milk oligosaccharides and Lewis blood group: individual high-throughput sample profiling to enhance conclusions from functional studies

Human milk oligosaccharides (HMO) are discussed to play a crucial role in an infant's development. Lewis blood group epitopes, in particular, seem to remarkably contribute to the beneficial effects of HMO. In this regard, large-scale functional human studies could provide evidence of the variety of results from in vitro investigations, although increasing the amount and complexity of sample and data handling. Therefore, reliable screening approaches are needed. To predict the oligosaccharide pattern in milk, the routine serological Lewis blood group typing of blood samples can be applied due to the close relationship between the biosynthesis of HMO and the Lewis antigens on erythrocytes. However, the actual HMO profile of the individual samples does not necessarily correspond to the serological determinations. This review demonstrates the capabilities of merging the traditional serological Lewis blood group typing with the additional information provided by the comprehensive elucidation of individual HMO patterns by means of state-of-the-art analytics. Deduced from the association of the suggested HMO biosynthesis with the Lewis blood group, the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry profiles of oligosaccharides in individual milk samples exemplify the advantages and the limitations of sample assignment to distinct groups.

Characterization of a monoclonal antibody specific for H type 2 structure of ABO blood group, and its use for measuring H type 2 on human red blood cells

A monoclonal antibody 3A5 specific for the human red blood cells was produced by immunizing BALB/c mouse with human erythrocyte membranes of group O following the immunization protocol of selectively killing the antigen-stimulated lymphocytes. The monoclonal antibody 3A5 we obtained agglutinated red blood cells regardless of individuals of blood group A, B, or O types, but not those from a person with a rare para-Bombay type which is the H-deficient phenotype. The hemagglutination reaction of 3A5 was not inhibited by saliva from either secretor or nonsecretor individuals. The specificity of 3A5 was studied by adsorption with and elution from synthetic oligosaccharide immunoadsorbents including H disaccharide, and H type 1, 2, 3, and 4 structures. Also, the reactivity of 3A5 with synthetic oligosaccharide-BSA complexes for H type 1, H type 2, Le(a), Le(b), A, and B was determined by an immunoassay. We found that 3A5 did not react with any of these synthetic oligosaccharides except H type 2. From these results, the antigenic epitope recognized by 3A5 was demonstrated to be the H type 2 structure. Additionally, the H type 2 substance on erythrocytes was quantitatively analyzed using 3A5.

Structural and immunochemical identification of Leb glycolipids in the plasma of a group O Le(a-b-) secretor

Total non-acid glycosphingolipids were isolated from the plasma of a healthy red blood cell group O Le(a-b-) salivary ABH secretor individual. Glycolipids were fractionated by HPLC and combined into eight fractions based on chromatographic and immunoreactive properties. These glycolipid fractions were analysed by thin-layer chromatography and tested for Lewis activity with antibodies reactive to the type 1 precursor (Le(c)), H type 1 (Le(d)), Le(a) and Le(b) epitopes. Fractions were structurally characterized by mass spectrometry (EI-MS and LSIMS) and proton NMR spectroscopy. Expected blood group glycolipids, such as H type 1, (Fuc alpha 1-2Gal beta 1-3GlcNac beta 1-3Gal beta 1-4Glc beta 1-1Cer) were immunochemically and structurally identified. Inconsistent with the red cell phenotype and for the first time, small quantities of Le(b) blood group glycolipids (Fuc alpha 1-2Gal beta 1-3(Fuc alpha 1-4)GlcNAc beta 1-4Glc beta 1-1Cer) were immunochemically and structurally identified in the plasma of a Lewis-negative individual. These findings confirm recent immunological evidence suggesting the production of small amounts of Lewis antigens by Lewis negative individuals.

Blood group antigens on human erythrocytes-distribution, structure and possible functions

Human erythrocyte blood group antigens can be broadly divided into carbohydrates and proteins. The carbohydrate-dependent antigens (e.g., ABH, Lewis, Ii, P1, P-related, T and Tn) are covalently attached to proteins and/or sphingolipids, which are also widely distributed in body fluids, normal tissues and tumors. Blood group gene-specific glycosyltransferase regulate the synthesis of these antigens. Protein-dependent blood group antigens (e.g., MNSs, Gerbich, Rh, Kell, Duffy and Cromer-related) are carried on proteins, glycoproteins and proteins with glycosylphosphatidylinositol anchor. The functions of these molecules on human erythrocytes remain unknown; some of them may be involved in maintaining the erythrocyte shape. This review describes the distribution, structures and probable biological functions of some of these antigens in normal and pathological conditions.

Serological and chemical specificities of twelve monoclonal anti-Lea and anti-Leb antibodies

The serological specificities of twelve hybridomas were compared as to their chemical reactivity as determined using direct binding to synthetic carbohydrate structures. All anti-Lea cross-react with type-1-precursor structures and three different variants of anti-Lea could be defined by their binding to type-3-precursor chains, sialylated compounds and the monosaccharide D-galactose. Three major reactivity patterns were also identified among anti-Leb reagents. Anti-LebL cross-react with Lea and do not significantly bind to H-related structures. Anti-LebH,L had both anti-LebL-like activity (cross-reaction with Lea) and anti-LebH-like activity (cross-reaction with H). Finally, anti-LebH cross-reacts strongly with H compounds and do not bind to Lea. The binding pattern of anti-LebL suggests that these antibodies have lower affinity for ALeb and BLeb pentasaccharides than anti-LebH. All these specificities are not absolute, but rather are expressed as members of a quantitative progressive varying series, suggesting the existence of a whole range of antibody specificities gradually changing from Lea----Lea,b----LebL----LebH,L----LebH. The results suggest that anti-LebL will always cross-react with Lea and that anti-LebH will always cross-react with H related structures. However, under certain well-defined conditions these cross-reactions may not be apparent and antibodies might behave as specific anti-Lea or anti-Leb in certain tests.

Human blood group glycosphingolipids of porcine erythrocytes

Two glycosphingolipids with human blood group A and H antigenicity were isolated from porcine erythrocyte membranes which were obtained from the pooled blood. The yield of the A- and H-antigenic glycolipids was approximately 0.2 and 0.1% of total neutral glycolipids, respectively. No B antigen was detected. Through several methods the porcine erythrocyte antigens were all found to belong to lactoseries (type 1 chain), IV2Fuc alpha, IV3GalNAc alpha Lc4Cer for type A and IV2-Fuc alpha Lc4Cer for type H, in contrast to the antigenic glycolipids in human erythrocytes, which mostly belong to neolactoseries (type 2 chain). The constituent fatty acids of the A antigen were 75% normal acids and 25% 2-hydroxy acids, and the long chain base was 95% sphingenine. This is the first demonstration of the A- and H-antigenic glycolipids on erythrocytes of pig in whose gastric mucin the human blood group A and H substances have been demonstrated.

Identification of a blood group A active hexaglycosylceramide with a type 1 carbohydrate chain in plasma of an A1 Le(a-b-) secretor

A blood group A active hexaglycosylceramide with a type 1 carbohydrate chain was identified in the plasma of an A1 Le(a-b-) secretor. The analysis was done on the total non-acid glycosphingolipid fraction using mass spectrometry, NMR spectroscopy, and anti-A antibody immunostaining on thin-layer chromatograms.

Genetics of ABO, H, Lewis, X and related antigens

The present knowledge on chemical, enzymatic, serologic and genetic aspects of ABH antigens is reviewed in an effort to produce a simple and coherent genetic model for the biosynthesis of these antigens and chemically related structures. The genetic control of type 1 (Le(a), Le(b), Le(c) and Le(d)), type 2 (X, Y, I, and H), type 3 and type 4 ABH and related antigens in different animal and human tissues is analyzed, taking into account the properties of the glycosyltransferases which are involved in their synthesis and considering possible competition for common acceptor and donor substrates. The phylogeny of ABH determinants shows that they appeared as tissular antigens much earlier than as red cell antigens. The ontogeny of ABH antigens suggests that they behave as differentiation antigens, and an effort is made to correlate their tissular distribution in the adult with the embryological origin of each tissue.

Immunochemistry of the Lewis blood-group system: isolation and structures of Lewis-c active and related glycosphingolipids from the plasma of blood-group O Le(a-b-) nonsecretors

Five different glycosphingolipid fractions (GL-3, 285 micrograms; GL-5, 1090 micrograms; GL-6, 615 micrograms; GL-7, 555 micrograms; and GL-8, 155 micrograms) have been isolated from 25 liters of plasma of O Le(a-b-) nonsecretors by means of ethanol extraction, several steps of Folch distribution, and reversed-phase, silicic acid, and ion-exchange column chromatography of native or peracetylated substances. Final purification, accomplished by preparative silica gel high-performance thin-layer chromatography, led to chromatographic homogeneity of GL-3 and GL-6. In the hemagglutination inhibition as well as quantitative passive hemagglutination techniques two of these substances (GL-3, GL-5) exhibited distinct, and the other three (GL-6-GL-8) very strong, Lec blood-group activities when tested against two different Lec antisera of human or goat origin. The fragments' structures were elucidated by fast atom bombardment and electron impact mass spectrometry of permethylated derivatives in order to determine molecular weight, sugar sequence, position of branching points, and type of oligosaccharide chains, as well as fatty acid and sphingosine patterns of the ceramide residue. Combined gas-liquid chromatography and mass spectrometry of partially methylated alditol acetates identified sugar composition and glycosidic linkages. Thus, the following structures could be established: (formula; see text) In contrast to the structurally homogeneous GL-3, minor amounts of 4-O-substituted GlcNAc pointed to a small contamination of GL-6 by branched type 2 ceramide nonasaccharide analogs. Glycolipids containing hepta- or nonasaccharides as in GL-3 or GL-6 could also be identified in fractions GL-5 (ceramide heptasaccharide) and GL-7 and GL-8 (ceramide nonasaccharide). These latter fractions revealed, however, distinct heterogeneity due to the presence of a small amount of either a type 2 analog of GL-3 (GL-5) or linear, mainly type 2, ceramide hexa- (GL-5, GL-7) or octasaccharides (GL-8). In addition to previous immunochemical communications the presented Lec active structures of GL-3 and GL-6 provide evidence that 3-fucosyl-N-acetyllactosamine in combination with a type 1 based oligosaccharide sequence and a 3,6-galactosyl branching point are essential parts of the Lec antigenic determinant (as marked in the formula of GL-6).

Glycosphingolipids of human plasma

A number of glycosphingolipids, including 10 gangliosides, not previously identified in human plasma have been characterized. The plasma contains 2 micrograms of lipid-bound sialic acid/ml plasma and 54% of the gangliosides are monosialo, 30% disialo, 10% trisialo, and 6% tetrasialo. Individual glycosphingolipids were purified by high-performance liquid chromatography and thin-layer chromatography, and were characterized on the basis of their chromatographic mobility, carbohydrate composition, hydrolysis by glycosidases, methylation analysis, and immunostaining with anti-glycosphingolipid antibodies. The monosialogangliosides were identified as GM3, GM2, sialosyl(2-3)- and sialosyl(2-6)lactoneotetraosylceramides, sialosyllacto-N-nor-hexaosylceramide, and sialosyllacto-N-isooctaosylceramide. The major gangliosides in the polysialo fractions contained a ganglio-N-tetraose backbone and were identified as GD3, GD1a, GD1b, and GQ1b. The most abundant neutral glycosphingolipids were glucosyl, lactosyl, globotriaosyl, globotetraosyl and lactoneotetraosylceramides. The other neutral glycosphingolipids, tentatively identified by immunostaining with monoclonal antibodies, contained H1, Lea, Leb, and lacto-N-fucopentose III (X hapten) structures.

Purification and structures of branched blood-group-B-active glycosphingolipids from human erythrocyte membranes

Three different variants of complex, branched, highly blood-group-B-active glycosphingolipids (B-III, B-IV, and B-V) have been isolated from human erythrocytes by means of partition of their membranes in n-butanol/phosphate buffer, subsequent removal of nonpolar lipids and proteins by several steps of phase distribution, acetone or sodium acetate precipitation, peracetylation and repeated fractionation of all crude extracts by silicic acid and ion exchange column chromatography. Finally, peracetylated B-glycolipid fractions were purified to homogeneity by preparative silica gel high-performance thin-layer chromatography. Their structures were elucidated by gas chromatographical sugar analysis, by combined gas chromatography/mass spectrometry of partially methylated alditol acetates for the identification of glycosidic linkages, and by fast atom bombardment and electron impact mass spectrometry of the undegraded, permethylated substances in order to establish the molecular mass, sugar sequence, type of oligosaccharide chain, position of hexosyl branching points, number of N-acetyllatosamine units, as well as sphingosine and fatty acid patterns of the ceramide residues. 360-MHz 1H nuclear magnetic resonance spectroscopy in (2H)dimethylsulfoxide of deuterium-exchanged native B-III and B-IV identified all carbohydrate components, their sites of attachment, the anomeric nature of their glycosidic linkages and the sequential arrangement within the oligosaccharide chain. Furthermore, it established the nature of branching points within the carbohydrate sequence, and assigned the different typical saccharide branches to either the position 2 versus 3, or position 3 versus 6 of the 2,3-disubstituted or 3,6-disubstituted galactoses. The nature of the anomeric linkages and branching points of B-V was based upon the series of NMR data obtained from the B-I--B-IV analogues. All results thus establish the following structures: (formula; see text)

Structures of fucose-containing ceramide pentasaccharides from the plasma of blood group O Le(a-b-) nonsecretors

A minor, Lec blood-group inactive ceramide pentasaccharide double band fraction has been isolated from the plasma of blood group O Le(a-b-) nonsecretors. The two purified glycolipids were analysed by NMR spectroscopy, mass spectrometry and combined gas chromatography-mass spectrometry. The following structures could be established: GlcNAc(beta 1----3)Gal(beta 1----4)Glc(beta 1----1)Cer (I); Gal(beta 1----4) [Fuc(alpha 1----3)]GlcNAc(beta 1----3)Gal(beta 1----4)Glc(beta 1----1)Cer (II). It must be concluded that at least part of the secretor gene-independent plasmatic H type 2 blood-group activity can be attributed to glycosphingolipid I, whereas substance II, originally detected in cancerous tissue, also occurs in the plasma of healthy individuals.

Solid-phase biosynthesis on high performance thin-layer plates of blood group glycosphingolipids II

A new method for the study of carbohydrate chain biosynthesis of amphipathic glycosphingolipids is presented. The method takes advantage of the thin-layer plate which is used as a solid matrix for precursor glycosphingolipids in biosynthetic experiments after chromatographic development of the precursor sample. The method is shown to be simple, fast and sensitive. It minimizes the risk of adding unwanted exogenous precursors and abolishes the need for tedious purification of products after incubation. The method opens up new possibilities for the biosynthetic study of mixtures of glycosphingolipids.

Chemical characterization of a blood group H type pentaglycosylceramide of human small intestine

A blood group H type pentaglycosylceramide was isolated in relatively large amounts from human adult small intestine (52 mg from one individual) and human meconium (fetal origin). The structure was made likely by mass spectrometry and NMR spectroscopy of non-degraded permethylated and permethylated-LiAlH4-reduced glycolipid and by degradation to be Fuc alpha 1 leads to 2Gal beta 1 leads to 3GlcNAc beta 1 leads to 3Gal beta 1 leads to 4Glc beta 1 leads to 1Cer. The ceramide was composed mainly of phytosphingosine and 2-hydroxy 16-24 carbon fatty acids. This novel type 1 chain species (Gal beta 1 leads to 3GlcNAc) was not accompanied by the type 2 chain isomer (Gal beta 1 leads to 4GlcNAc) which in contrast is the sole species in human erythrocyte and dog small intestine.

Lea blood group substance degradation in the human alimentary tract and urinary Lea in coeliac disease

The Lewis (Lea) blood group substance in alimentary tract liquids is a large molecule. Ileal and jejunal mucosal preparations can act upon it to produce dialysable serologically active Lea. Alimentary tract bacteria cannot produce a similar effect. Plasma, serum and urinary Lea are principally in the form of a dialysable moiety. It is suggested that this dialysable form is produced by mucosal degradation of large-molecule Lea in the alimentary tract. The small-molecule Lea is absorbed, transported in the plasma and then excreted. Both secretor and non-secretor patients with duodenal ulcer and inflammatory bowel disease have normal urinary Lea titres. Non-secretor coeliac patients who have not regenerated normal jejunal mucosa on treatment have significantly reduced urinary Lea titres when compared with healthy individuals. One non-secretor coeliac patient who had regenerated a normal jejunal mucosa on treatment had a normal urinary Lea titre. Coeliac patients have normal titres of salivary Lea.

Purification of anti-Lec antibodies with specificity for beta DGal(1 replaced by 3)beta DGlcNAcO- using a synthetic immunoadsorbent

Artificial antigens: Antibodies were raised in rabbits with beta DGal(1 linked to 3)beta DGlcNAc-BSA and purified by absorption elution on a column of the synthetic oligosaccharide covalently bound to a silicate instead of BSA. The purified antibodies agglutinated specifically erythrocytes from Le (a-b-) nonsecretor donors (Lec). Natural antigens: Antibodies were raised in goats using boiled saliva from O/O, le/le, se/se donors. The population of antibodies which was absorbed on a column consisting of beta DGal(1 linked to 3)etaDGlcNAc-O-R (type 1 chain precursor disaccharide) groupings attached to a silicate was collected and then refined by passage through a column which consisted of similarly immobilized alpha LFuc(1 linked to 2)beta DGal(1 linked to 3)betaGDlcNAc-(H type 1), beta(DGal(1 linked to 3)-[alpha LFuc(1 linked to 4)]beta DGlcNAc-(Lea), and beta DGal(1 replaced by 4)beta DGlcNAc-(type 2 core chain precursor) groupings. The refined antibodies proved to have a reaction pattern with salivas that is the same as that previously reported for anti-Lec sera. The data obtained with natural and artificial antigens are thus compatible with the biosynthetic pathway for the formation of the Lewis antigenic determinants proposed by Graham and suggest that the Lec antigen may simply be the type 1 precursor chain which is required for the formation of the Lea, Led and Leb antigenic determinants.