Human ABO Blood Group Research Articles

Novel lectins from rhizomes of two Acorus species with mitogenic activity and inhibitory potential towards murine cancer cell lines

Two novel lectins were purified from rhizomes of two sweet flag species, namely Acorus calamus (Linn.) and Acorus gramineus (Solandin Ait.) by affinity chromatography on mannose linked epoxy-activated Sepharose 6B. The apparent molecular mass of the lectins, as determined by gel filtration chromatography, was 56 kDa for ACL and 55 kDa for AGL. In SDS–PAGE, pH 8.3, both lectins migrated with a subunit molecular mass of 13.6 kDa and 13.5 kDa, respectively, under reducing and non-reducing conditions thus indicating the absence of disulphide linkages. Acorus lectins readily agglutinated rabbit, rat and guinea pig erythrocytes. Both ACL and AGL also reacted with RBCs from sheep, goat and human ABO blood groups after neuraminidase treatment. ACL and AGL were inhibited by mannose/glucose and their derivatives. The most effective inhibitor was methyl-α- d-mannopyranoside. Acorus lectins were stable up to 55 °C, did not require metal ions for their activity and were also affected by high concentrations of denaturants like urea, thiourea and guanidine–HCl. These lectins showed potent mitogenic activity towards mouse splenocytes and human lymphocytes. Both ACL and AGL also significantly inhibited the growth of J774, a murine macrophage cancer cell-line and to lesser extent WEHI-279, a B-cell lymphoma.

Mitogenic and anti-proliferative activity of a lectin from the tubers of Voodoo lily (Sauromatum venosum)

A new lectin with the potent mitogenic and in vitro anti-proliferative activity was isolated from the tubers of a wild monocotyledonous plant Sauromatum venosum (Schott), from the family Araceae, by affinity chromatography on the asialofetuin linked amino-activated silica beads. The apparent native molecular mass of S. venosum lectin (SVL), as determined by gel filtration chromatography, was 54 kDa. In HPLC, size exclusion and cation exchange chromatography, SVL gave a single peak and also a single band of 13.5 kDa in SDS-PAGE, pH 8.3, under reducing and non-reducing conditions, indicating that the lectin is composed of four identical subunits. S. venosum lectin agglutinated rabbit, rat, sheep and guinea pig erythrocytes but reacted with goat erythrocytes after the neuraminidase treatment. However, SVL was unable to agglutinate human ABO blood group erythrocytes even after treatment with neuraminidase. SVL was inhibited by N-acetyl-D-Lactosamine (LacNAc), which is an important marker in various carcinomas and a complex desialylated glycoprotein, asialofetuin. The amino acid composition showed that lectin contained a high amount of aspartic acid and glycine but totally devoid of cysteine. However, trace amounts of methionine was present. The lectin showed a potent mitogenic response towards BALB/c splenocytes and human lymphocytes. As the mitogenic stimulation was more than that of Con A, a standard well-known plant mitogen and the response of this lectin was almost double than that of Con A. This lectin is endowed with proliferation of T cells as revealed by IL-2 bioassay but showed no production of immunoglobulins thus indicating the non-stimulation of B cells. SVL significantly inhibited the proliferation of murine cancer cell-lines, i.e., WEHI-279 to 84.6%, J774 to 81%, P388D1 to 74% and A-20 to 47%. In addition, the in vitro anti-proliferative activity of SVL was also evaluated against nine human cancer cell lines representing different organs and tissues namely, T-47D (breast), SiHa (cervix), SK-N-MC (CNS), SK-N-SH (CNS), SW-620 (colon), HT-29 (colon), HEP-2 (liver), OVCAR-5 (ovary) and PC-3 (prostate). SVL showed a significant inhibition towards the entire cell lines except the cell lines from CNS, which showed partial response in comparison to a standard anticancer drug adriamycin which was used at a concentration of 5 x 10(-5) M. Thus the anti-proliferative ability of SVL may be helpful in identification of new lectin probes that can lead to better understanding in the detection and study of certain types of cancer.

Structural Basis for the Inactivity of Human Blood Group O2 Glycosyltransferase

The human ABO(H) blood group antigens are carbohydrate structures generated by glycosyltransferase enzymes. Glycosyltransferase A (GTA) uses UDP-GalNAc as a donor to transfer a monosaccharide residue to Fuc alpha1-2Gal beta-R (H)-terminating acceptors. Similarly, glycosyltransferase B (GTB) catalyzes the transfer of a monosaccharide residue from UDP-Gal to the same acceptors. These are highly homologous enzymes differing in only four of 354 amino acids, Arg/Gly-176, Gly/Ser-235, Leu/Met-266, and Gly/Ala-268. Blood group O usually stems from the expression of truncated inactive forms of GTA or GTB. Recently, an O(2) enzyme was discovered that was a full-length form of GTA with three mutations, P74S, R176G, and G268R. We showed previously that the R176G mutation increased catalytic activity with minor effects on substrate binding. Enzyme kinetics and high resolution structural studies of mutant enzymes based on the O(2) blood group transferase reveal that whereas the P74S mutation in the stem region of the protein does not appear to play a role in enzyme inactivation, the G268R mutation completely blocks the donor GalNAc-binding site leaving the acceptor binding site unaffected.

A novel mitogenic and antiproliferative lectin from a wild cobra lily, Arisaema flavum

A novel lectin having specificity towards a complex glycoprotein asialofetuin was purified from tubers of Arisaema flavum (Schott.) by affinity chromatography on asialofetuin-linked amino-activated silica beads. A. flavum gave a single peak on HPLC size exclusion and a single band on non-denatured PAGE at pH 4.5. The molecular mass of the lectin, as determined by gel filtration chromatography, was 56 kDa. In SDS–PAGE, pH 8.3, the lectin migrated as a single band of 13.5 kDa, under reducing and non-reducing conditions, indicating the homotetrameric nature. A. flavum lectin (AFL) readily agglutinated rabbit, rat, sheep, goat, and guinea pig erythrocytes but not human ABO blood group erythrocytes even after neuraminidase treatment. This lectin is stable up to 55 °C and does not require metal ions for its hemagglutination activity. AFL was completely devoid of sulphur containing amino acids and was rich in aspartic acid and glycine. In Oucterlony’s double immunodiffusion, the antisera raised against A. flavum lectin showed distinct lines of identity with those of other araceous lectins. AFL showed potent mitogenic activity towards BALB/c splenocytes and human lymphocytes in comparison to Con A, a well-known plant mitogen. AFL also showed significant in vitro antiproliferative activity towards J774 and P388D1 murine cancer cell lines.

A novel mitogenic and antiproliferative lectin from a wild cobra lily, Arisaema flavum

A novel lectin having specificity towards a complex glycoprotein asialofetuin was purified from tubers of Arisaema flavum (Schott.) by affinity chromatography on asialofetuin-linked amino-activated silica beads. A. flavum gave a single peak on HPLC size exclusion and a single band on non-denatured PAGE at pH 4.5. The molecular mass of the lectin, as determined by gel filtration chromatography, was 56 kDa. In SDS–PAGE, pH 8.3, the lectin migrated as a single band of 13.5 kDa, under reducing and non-reducing conditions, indicating the homotetrameric nature. A. flavum lectin (AFL) readily agglutinated rabbit, rat, sheep, goat, and guinea pig erythrocytes but not human ABO blood group erythrocytes even after neuraminidase treatment. This lectin is stable up to 55 °C and does not require metal ions for its hemagglutination activity. AFL was completely devoid of sulphur containing amino acids and was rich in aspartic acid and glycine. In Oucterlony’s double immunodiffusion, the antisera raised against A. flavum lectin showed distinct lines of identity with those of other araceous lectins. AFL showed potent mitogenic activity towards BALB/c splenocytes and human lymphocytes in comparison to Con A, a well-known plant mitogen. AFL also showed significant in vitro antiproliferative activity towards J774 and P388D1 murine cancer cell lines.

Evolution of the O alleles of the human ABO blood group gene.

To date, at least 40 different alleles O have been characterized on the basis of exon 6 and exon 7 sequences but not always for intron 6. Among 415 individuals, from four continents (Africa, Europe, South America, and Asia), studied for exon 6 and exon 7 sequences, we selected 46 individuals (of respective phenotypes O [39], AB [3], B [3], or A [1]) for sequencing 1800-bp amplicons spanning exon 6, intron 6, and exon 7. The amplicons were characterized either by direct sequencing or after cloning when required. We defined 14 new intron 6 O allele sequences, including four recombinant alleles. Based on sequence comparison, a phylogenetic network was constructed. It confirmed recombinant allele origins and that most O alleles are derived by point mutations from the two worldwide distributed alleles O01 and O02. Allele O phylogenetic analysis suggests that the most frequent silencing mutation (deletion of a G in exon 6) appeared once in human evolution in the ancient O02 allele lineage and that allele O01 resulted from an interallele exchange between O02 and A101. Assuming constancy of evolutionary rate, diversification of the representative alleles of the three human ABO lineages (A101, B101, and O02) was estimated at 4.5 to 6 million years ago.

The Influence of an Intramolecular Hydrogen Bond in Differential Recognition of Inhibitory Acceptor Analogs by Human ABO(H) Blood Group A and B Glycosyltransferases

Human ABO(H) blood group glycosyltransferases GTA and GTB catalyze the final monosaccharide addition in the biosynthesis of the human A and B blood group antigens. GTA and GTB utilize a common acceptor, the H antigen disaccharide alpha-l-Fucp-(1-->2)-beta-d-Galp-OR, but different donors, where GTA transfers GalNAc from UDP-GalNAc and GTB transfers Gal from UDP-Gal. GTA and GTB are two of the most homologous enzymes known to transfer different donors and differ in only 4 amino acid residues, but one in particular (Leu/Met-266) has been shown to dominate the selection between donor sugars. The structures of the A and B glycosyltransferases have been determined to high resolution in complex with two inhibitory acceptor analogs alpha-l-Fucp(1-->2)-beta-d-(3-deoxy)-Galp-OR and alpha-l-Fucp-(1-->2)-beta-d-(3-amino)-Galp-OR, in which the 3-hydroxyl moiety of the Gal ring has been replaced by hydrogen or an amino group, respectively. Remarkably, although the 3-deoxy inhibitor occupies the same conformation and position observed for the native H antigen in GTA and GTB, the 3-amino analog is recognized differently by the two enzymes. The 3-amino substitution introduces a novel intramolecular hydrogen bond between O2' on Fuc and N3' on Gal, which alters the minimum-energy conformation of the inhibitor. In the absence of UDP, the 3-amino analog can be accommodated by either GTA or GTB with the l-Fuc residue partially occupying the vacant UDP binding site. However, in the presence of UDP, the analog is forced to abandon the intramolecular hydrogen bond, and the l-Fuc residue is shifted to a less ordered conformation. Further, the residue Leu/Met-266 that was thought important only in distinguishing between donor substrates is observed to interact differently with the 3-amino acceptor analog in GTA and GTB. These observations explain why the 3-deoxy analog acts as a competitive inhibitor of the glycosyltransferase reaction, whereas the 3-amino analog displays complex modes of inhibition.

Karl landsteiner and his major contributions to haematology

Karl landsteiner and his major contributions to haematology

Potential implications of ABO blood group for vascular rejection in pig to human kidney xenotransplantation.

A substantial hurdle for successful xenotransplantation is to negate the effect of xenoreactive natural antibodies [mainly Galalpha1-3Galbeta1-4GlcNAc (alpha-Gal) specific] that cause hyperacute xenograft rejection. Galalpha1-3Gal molecules (alpha-Gal) have close structural homology with human ABO blood groups and therefore an individual's blood group might influence the formation of alpha-Gal specific antibodies. Genetic heterogeneity controlling alpha-Gal specific antibody formation could have important implications for future pig to human xenotransplantation clinical trials. We have investigated the relationship between ABO blood group and immunoglobulin M (IgM) and immunoglobulin G (IgG) alpha-Gal specific antibody titres in sera obtained from renal dialysis patients and healthy blood donors. Serially diluted sera (n = 166) obtained from renal dialysis patients awaiting kidney transplantation (n = 116) and healthy blood donors (n = 50) were tested for IgM and IgG alpha-Gal antibodies using an enzyme-linked immunosorbent assay (ELISA) specific for alpha-Gal. The study cohort comprised 62, 48, 36 and 20 sera obtained from blood group O, A, B and AB individuals, respectively. Reciprocal alpha-Gal specific antibody titres were calculated from ELISA titration curves and stratified by individual blood group. No significant heterogeneity was found in IgM alpha-Gal specific antibody titres across ABO blood groups. In contrast, marked heterogeneity was observed in IgG alpha-Gal specific antibody titres when stratified by blood group. IgG alpha-Gal specific antibody titres were higher in sera obtained from blood group O renal dialysis patients [median titre 40, interquartile range (IQR) 14 to 72], compared with blood group A (median titre 18, IQR 7 to 54, P = 0.05), blood group B (median titre 6, IQR 0 to 15, P < 0.001) and blood group AB patients (median titre 3.5, IQR 0 to 16, P = 0.002). A similar correlation was found for IgG alpha-Gal specific antibody titres in sera obtained from healthy blood donors with median titres of 20 (IQR 12 to 34), 37 (10 to 91), 9 (0 to 20), and 5.5 (0 to 12) in blood groups O, A, B and AB individuals, respectively. There was a strong interrelationship between alpha-Gal specific antibody class and blood group, with both IgM and IgG alpha-Gal specific antibodies found in 84% of the blood group O sera, 73% of blood group A sera, 50% of blood group B sera and 40% of blood group AB sera (P < 0.001). In a subgroup of 39 renal dialysis patients, IgM and IgG alpha-Gal specific antibody titres were measured in two serum samples obtained at different time-points (median time interval 581 days, range 42 to 4414), and showed a high degree of stability (correlation coefficient 0.88 and 0.90 for IgM and IgG, respectively). IgG alpha-Gal specific antibody titres are significantly higher in the sera of blood group O and A renal dialysis patients and healthy individuals compared with blood groups B and AB. These data indicate that future clinical trials of pig to human xenotransplantation may be more problematic for non-blood group B patients who are likely to have high levels of IgG alpha-Gal specific antibodies that are associated with acute vascular rejection.

Aspectos moleculares do Sistema Sangüíneo ABO

O sistema ABO é o mais importante grupo sangüíneo na medicina transfusional. O gene ABO codifica as glicosiltransferases responsáveis pela transferência dos resíduos específicos de açúcar, GalNaca1-3 e Gala 1-3, ao substrato H e os convertem ao antígeno A ou B respectivamente. A estrutura do DNA dos três principais alelos do sistema ABO, A¹, B e O foi primeiramente descrita em 1990. Os avanços da genética molecular permitiram o entendimento da base molecular dos genes ABO e o conhecimento do polimorfismo dos alelos comuns a esse locus. Essa revisão tem como objetivo o estudo dos alelos variantes desse sistema, assim como a compreensão das mutações, deleções ou rearranjo de genes responsáveis pela ocorrência de alguns dos subgrupos do sistema ABO. As técnicas mais comumente utilizadas para a genotipagem ABO também são avaliadas, bem como suas vantagens e limitações.

The structural basis for specificity in human ABO(H) blood group biosynthesis.

The human ABO(H) blood group antigens are produced by specific glycosyltransferase enzymes. An N-acetylgalactosaminyltransferase (GTA) uses a UDP-GalNAc donor to convert the H-antigen acceptor to the A antigen, whereas a galactosyltransferase (GTB) uses a UDP-galactose donor to convert the H-antigen acceptor to the B antigen. GTA and GTB differ only in the identity of four critical amino acid residues. Crystal structures at 1.8-1.32 A resolution of the GTA and GTB enzymes both free and in complex with disaccharide H-antigen acceptor and UDP reveal the basis for donor and acceptor specificity and show that only two of the critical amino acid residues are positioned to contact donor or acceptor substrates. Given the need for stringent stereo- and regioselectivity in this biosynthesis, these structures further demonstrate that the ability of the two enzymes to distinguish between the A and B donors is largely determined by a single amino acid residue.

Characterization of the human ABO gene promoter in erythroid cell lineage.

The human ABO blood group system is important in transfusion and organ transplantation. Although the molecular basis of the ABO gene has been established, recent studies have begun to characterize the mechanism of the ABO gene expression. Transient transfection assays were carried out in human erythroleukaemia HEL cells and human gastric cancer KATOIII cells. Electrophoretic mobility shift assays were performed using nuclear extracts derived from both cells. Our characterization of the 5'-upstream sequence of the ABO genes indicated that the region between -117 and +31 is essential to direct expression of a reporter gene in erythroid cells. We show that a sequence located between positions -22 and -14 of the ABO promoter binds a ubiquitous transcription factor Sp1 or Sp1-like protein(s). Mutation of this site abrogates binding of those factors and reduces the ability of the ABO promoter to function in erythroleukaemia cells and gastric cancer cells. The expression of the ABO promoter appears to be influenced by the binding of Sp1 or Sp1-like protein(s) in both erythroid and epithelial cell lineages.

Carbohydrate specificity of a galectin from chicken liver (CG-16).

Owing to the expression of more than one type of galectin in animal tissues, the delineation of the functions of individual members of this lectin family requires the precise definition of their carbohydrate specificities. Thus, the binding properties of chicken liver galectin (CG-16) to glycoproteins (gps) and Streptococcus pneumoniae type 14 polysaccharide were studied by the biotin/avidin-mediated microtitre-plate lectin-binding assay and by the inhibition of lectin-glycan interactions with sugar ligands. Among 33 glycans tested for lectin binding, CG-16 reacted best with human blood group ABO (H) precursor gps and their equivalent gps, which contain a high density of D-galactopyranose(beta1-4)2-acetamido-2-deoxy-D-glucopyranose [Gal(beta1-4)GlcNAc] and Gal(beta1-3)GlcNAc residues at the non-reducing end, but this lectin reacted weakly or not at all with A-,H-type and sialylated gps. Among the oligosaccharides tested by the inhibition assay, the tri-antennary Gal(beta1-4)GlcNAc (Tri-II) was the best. It was 2.1x10(3) nM and 3.0 times more potent than Gal and Gal(beta1-4)GlcNAc (II)/Gal(beta1-3)GlcNAc(beta1-3)Gal(beta1-4)Glc (lacto-N-tetraose) respectively. CG-16 has a preference for the beta-anomer of Gal at the non-reducing end of oligosaccharides with a Gal(beta1-4) linkage >Gal(beta1-3)> or =Gal(beta1-6). From the results, it can be concluded that the combining site of this agglutinin should be a cavity type, and that a hydrophobic interaction in the vicinity of the binding site for sugar accommodation increases the affinity. The binding site of CG-16 is as large as a tetrasaccharide of the beta-anomer of Gal, and is most complementary to lacto-N-tetraose and Gal(beta1-4)GlcNAc related sequences.

Carbohydrate specificity of a galectin from chicken liver (CG-16)

Owing to the expression of more than one type of galectin in animal tissues, the delineation of the functions of individual members of this lectin family requires the precise definition of their carbohydrate specificities. Thus, the binding properties of chicken liver galectin (CG-16) to glycoproteins (gps) and Streptococcus pneumoniae type 14 polysaccharide were studied by the biotin/avidin-mediated microtitre-plate lectin-binding assay and by the inhibition of lectin–glycan interactions with sugar ligands. Among 33 glycans tested for lectin binding, CG-16 reacted best with human blood group ABO (H) precursor gps and their equivalent gps, which contain a high density of d-galactopyranose(β1–4)2-acetamido-2-deoxy-d-glucopyranose [Gal(β1–4)GlcNAc] and Gal(β1–3)GlcNAc residues at the non-reducing end, but this lectin reacted weakly or not at all with A-,H-type and sialylated gps. Among the oligosaccharides tested by the inhibition assay, the tri-antennary Gal(β1–4)GlcNAc (Tri-II) was the best. It was 2.1×103 nM and 3.0 times more potent than Gal and Gal(β1–4)GlcNAc (II)/Gal(β1–3)GlcNAc(β1–3)Gal(β1–4)Glc (lacto-N-tetraose) respectively. CG-16has a preference for the β-anomer of Gal at the non-reducing end of oligosaccharides with a Gal(β1–4) linkage &amp;gt;Gal(β1–3)Gal(β1–6). From the results, it can be concluded that the combining site of this agglutinin should be a cavity type, and that a hydrophobic interaction in the vicinity of the binding site for sugar accommodation increases the affinity. The binding site of CG-16 is as large as a tetrasaccharide of the β-anomer of Gal, and is most complementary to lacto-N-tetraose and Gal(β1–4)GlcNAc related sequences.

Polymorphism and recombination events at the ABO locus: a major challenge for genomic ABO blood grouping strategies.

The blood group ABO gene codes for a glycosyltransferase that adds the ultimate monosaccharide to a glycoconjugate and forms the A or B blood group specific antigen. The DNA structure of the three major alleles of the human blood group ABO system was first described in 1990. This review describes the subsequent developments, including the increasing number of variants of these common alleles and the underlying mutations thought to be responsible for the occurrence of some of the weak subgroups of blood group A and B. Several inactive (O) alleles are also now known. Our knowledge of the DNA sequence of the normal A and B alleles and of the rare and intriguing cisAB and B(A) phenotypes has resulted in plausible explanations for these. Allelic variations outside the translated exons have been investigated and resulted in detection of lineage-specific intron mutations and the discovery of an enhancer VNTR region affecting the rate of transcription at this locus. The occurrence of hybrid alleles can also explain hitherto abnormal inheritance in some pedigrees. The detection of hybrid alleles has been made possible by the presence of numerous polymorphisms found in the various ABO alleles. The role of chi (chi) sequences is discussed. Finally, the various genotyping methods available are summarized and their advantages and limitations are analysed in the light of the increasing allelic variation.

Gene diversity of chimpanzee ABO blood group genes elucidated from exon 7 sequences

Human and non-human primate ABO blood group genes show relatively large numbers of nucleotide differences. In this study, we determined exon 7 sequences for 10 individuals of common chimpanzee and for four individuals of bonobo to estimate nucleotide diversities among them. Sequence data showed the existence of chimpanzee specific 9-base deletion in the beginning of the exon 7 coding region. From a phylogenetic network of exon 7 sequences of ABO blood group genes for human, common chimpanzee, bonobo and gorilla, effects of parallel substitutions and/or some kinds of convergent events are inferred in the chimpanzee lineage. We also estimated nucleotide diversities for common chimpanzee and bonobo ABO blood group genes, and these values were 0.4% and 0.2%, respectively. These values are higher than that of most human genes.

DNA polymorphisms in the 5′-flanking sequence of human ABO blood group genes and their association with the alleles for the common ABO phenotypes

Previously we found that minisatellite located on the 5′-flanking sequence far from the transcription start site of the human ABO blood group genes and containing four tandem repeats of a 43 base pair (bp) consensus sequence was an enhancer element for the transcription of the ABO genes. Concerning the number of tandem repeats in the minisatellite, there are at least three alleles: ABOU1*1, ABOU1*3, and ABOU1*4. Besides the variability of the minisatellite, another location of the 5′-flanking sequence has two alleles associated with the insertion of the 35 bp DNA segment: ABOU2*0 allele with an uneventful sequence and ABOU2*1 allele with the 35-bp insertion, respectively. Both of the DNA polymorphisms are closely associated with the common alleles of blood group ABO phenotypes. Namely, the 5′-flanking configuration consisting of the alleles ABOU1*1 and ABOU2*0 links up with the common A1 allele, whereas, the other 5′-flanking configuration consisting of the alleles ABOU1*4 and ABOU2*1 links up with common B and O alleles (abbreviated as 1-0-A1, 4-1-B and 4-1-O). In these linkages between three loci of alleles of 102 unrelated healthy individuals, two are not consistent with the rules described above. One is 3-1-O and the other is 4-1-A2. These findings suggest that the 3 or 4 times repeats of a 43 bp consensus sequence at ABOU1 locus and the 35 bp-insertion at ABOU2 locus found in 5′-flanking sequence of the B and O genes are incidental to the ABO gene evolution, subject to the ancestral A1 gene.

Studies on the binding site of the galactose-specific agglutinin PA-IL from Pseudomonas aeruginosa.

The binding properties of Pseudomonas aeruginosa agglutinin-I (PA-IL) with glycoproteins (gps) and polysaccharides were studied by both the biotin/avidin-mediated microtiter plate lectin-binding assay and the inhibition of agglutinin-glycan interaction with sugar ligands. Among 36 glycans tested for binding, PA-IL reacted best with two glycoproteins containing Galalpha1-->4Gal determinants and a human blood group ABO precursor equivalent gp, but this lectin reacted weakly or not at all with A and H active gps or sialylated gps. Among the mammalian disaccharides tested by the inhibition assay, the human blood group Pkactive Galalpha1-->4Gal, was the best. It was 7.4-fold less active than melibiose (Galalpha1-->6Glc). PA-IL has a preference for the alpha-anomer in decreasing order as follows: Galalpha1-->6 >Galalpha1-->4 >Galalpha1-->3. Of the monosaccharides studied, the phenylbeta derivatives of Gal were much better inhibitors than the methylbeta derivative, while only an insignificant difference was found between the Galalpha anomer of methyl- and p -NO2-phenyl derivatives. From these results, it can be concluded that the combining size of the agglutinin is as large as a disaccharide of the alpha-anomer of Gal at nonreducing end and most complementary to Galalpha1-->6Glc. As for the combining site of PA-IL toward the beta-anomer, the size is assumed to be less than that of Gal; carbon-6 in the pyranose form is essential, and hydrophobic interaction is important for binding.

Evolution of primate ABO blood group genes and their homologous genes.

There are three common alleles (A, B, and O) at the human ABO blood group locus. We compared nucleotide sequences of these alleles, and relatively large numbers of nucleotide differences were found among them. These differences correspond to the divergence time of at least a few million years, which is unusually large for a human allelic divergence under neutral evolution. We constructed phylogenetic networks of human and nonhuman primate ABO alleles, and at least three independent appearances of B alleles from the ancestral A form were observed. These results suggest that some kind of balancing selection may have been operating at the ABO locus. We also constructed phylogenetic trees of ABO and their evolutionarily related alpha-1,3-galactosyltransferase genes, and the divergence time between these two families was estimated to be roughly 400 MYA.

Blood group phenotype determines lectin-mediated adhesion of Pseudomonas aeruginosa to human outer ear canal epithelium

Pseudomonas aeruginosa is the most frequent bacterial pathogen causing acute diffuse otitis externa. In a recent prospective phase II study we demonstrated that lectin-mediated bacterial adhesion can be blocked by receptor-analogue carbohydrates in patients suffering from Pseudomonas aeruginosa-induced acute otitis externa. In this investigation, human ABO blood group antigens were analysed on outer ear canal epithelial cells with standard routine histological procedures by monoclonal antibodies for the blood groups A and B, and with Ulex europaeus I lectin for the blood group O, respectively. In all cases (n = 20) the blood groups could be shown immunohistologically. P. aeruginosa-specific adhesion and inhibition assays were performed in the presence of N-acetylgalactosamine (GalNAc), N-acetylglucosamine (GlcNAc), D-mannose and A-like substance. Outer ear canal tissue sections were incubated with P. aeruginosa (strain PA 60), presenting lectin-specificity for GalNAc. Sections from patients presenting with blood group A were closely settled with bacteria in the presence of non-specific GlcNAc, D-mannose and PBS however, GalNAc and A-like substance inhibited the microbial adhesion. Amongst others, P. aeruginosa present adhesion molecules (lectins) with specificity for GalNAc. Thus, the correlation between blood group A phenotype and P. aeruginosa-induced acute diffuse otitis externa was investigated. Statistical evaluation proved a highly significant association. These data support the hypothesis that P. aeruginosa lectins with GalNAc specificity apparently adhere to GalNAc moieties, representing the terminal blood group A-determinant and further indicate that patients presenting with blood group A may have a genetic disposition for this form of otitis externa.