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The molecular genetic basis of the P histo-blood group system has eluded characterization despite extensive studies of the biosynthesis of the P 1 , P, and P k glycolipids. The main controversy has been whether a single or two distinct UDP-Gal:Gal␤1-R 4-␣-galactosyltransferases catalyze the syntheses of the structurally related P 1 and P k antigens. The P 1 polymorphism is linked to 22q11.3-ter. Data base searches with the coding region of an ␣4GlcNAc-transferase identified a novel homologous gene at 22q13.2 designated ␣4Gal-T1. Expression of full coding constructs of ␣4Gal-T1 in insect cells revealed it encoded P k but not P 1 synthase activity. Northern analysis showed expression of the transcript correlating with P k synthase activity and antigen expression in human B cell lines. Transfection of P k -negative Namalwa cells with ␣4Gal-T1 resulted in strong P k expression. A single homozygous missense mutation, M183K, was found in six Swedish individuals of the rare p phenotype, confirming that ␣4Gal-T1 represented the P k gene. Sequence analysis of the coding region of ␣4Gal-T1 in P 1 ؉/؊ individuals did not reveal polymorphisms correlating with P 1 P 2 typing.The P histo-blood group system is the last of the known carbohydrate defined blood group systems for which the molecular genetic basis has not yet been clarified. The P blood group system involves two major blood group phenotypes, P 1 ϩ and P 1 Ϫ, with approximate frequencies of 80% and 20%, respectively (1, 2). P 1 Ϫ individuals normally express the P antigen (P 1 Ϫ is designated P 2 when P antigen expression is demonstrated), but the rare P k phenotype lacks the P antigen, while the rare p phenotype lack both P and P k antigens (for reviews, see Refs. 3-7). The P 1 ϩ phenotype is defined by expression of the neolacto-series glycosphingolipid P 1 (for structures, see Table I) (8). In contrast, the P, P k , and p antigens constitute intermediate steps in biosynthesis of globo-series glycolipids and give rise to P 1 k , P 2 k , and p phenotypes (9). Although the rare P k phenotype shows the same frequency of P 1 antigen expression as individuals expressing the P antigen, the p phenotype is always associated with lack of P 1 antigen expression. Extensive studies of the chemistry, biosynthesis, and genetics of the P blood group system identified the antigens as being exclusively found on glycolipids, with the blood group specificity being synthesized by at least two distinct glycosyltransferase activities; UDP-galactose:␤-D-galactosyl-␤1-R 4-␣-Dgalactosyltransferase (␣4Gal-T) 1 activity(ies) for P k and P 1 syntheses and UDP-GalNAc:Gb 3 3-␤-N-acetylgalactosaminyltransferase activity (EC 2.4.1.79) for P synthesis (for reviews, see Refs. 6 and 7). At least two independent gene loci, P and P 1 P k , are involved in defining these antigens. The P blood group-associated LKE antigen, shown to be the extended sialylated Gal-globoside structure (10), may involve polymorphism in an ␣2,3-sialyltransferase activity.A long-standing controversy has been whether a single...

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Escherichia coli strains with defined receptor specificity were used as probes to analyze the individual variation in host cell receptors with respect to blood groups. The adhesins were initially characterized as mannose sensitive (MS), mannose resistant (MR), or nonagglutinating (-). The receptor specificity of the strains with MR adhesins was defined by agglutination of synthetic Galkl-4Galp covalently linked via a spacer arm, (CH2)2S(CH2)2CO-H-bovine serum albumin (BSA) to BSA-latex beads as specific for the globoseries glycolipid receptors (MR:GS). Strains with MR adhesins not reacting with Gala1-4Gal0-BSAlatex were designated MR:nonGS. The attachment and hemagglutination of the MR:GS strains was strictly dependent on Galal-*4Galp-containing receptors, as shown by the absence of binding to cells from individuals of blood group P lacking these structures. Previous reports showed differences in the composition of globoseries glycolipids between erythrocytes from individuals of P1 and P2. No significant difference was found, However, in the the mean adhesion to P1 and P2 epithelial cells or in the agglutination titer for P1 and P2 erythrocytes. The MR:GS receptors were equally distributed on squamous and transitional epithelial cells. In contrast, the distribution of MR:nonGS receptors was skewed. Attachment occurred mostly to squamous epithelial cells. The attachment of strains with MR:nonGS adhesins was independent of the P blood group of the cell donor. The binding ability of MR:GS and MR:nonGS adhesins appeared independent and additive. The attachment was not influenced by the ABH blood group. However, increased binding to epithelial cells from nonsecretors occurred regardless of the P blood group, suggesting a shielding of receptors by products controlled by the secretor genes. These results illustrate how individual variation in cell surface components with and without receptor activity determine the interaction of a ligand with a known receptor. Adhesive capacity is a virulence factor for Escherichia coli causing upper urinary tract infection (25). The attachment results from the interaction of host cell receptors with bacterial surface structures known as adhesins (14). Since the exact structures of the adhesins remain to be determined, they are classified according to either target cell specificity or, in some instances, receptor specificity (when the receptor structure has been identified). Wild-type bacteria, e.g., urinary E. coli isolates, can coexpress several adhesins, even on a single bacterial cell (5, 10). Receptors for attaching bacteria can consist of host cell surface carbohydrates, i.e., either glycoproteins or glycolipids (12). Several glycoconjugate specificities have been suggested to mediate adhesion or hemagglutination of uropathogenic E. coli, including mannose (19), N-acetylglucosamine (27), M antigen (28), NeuAca2-3Gal (21), and 919

A 12-week-old fetus and one 17-week-old fetus + placenta were obtained after spontaneous abortions from two women of blood group p. The 17-week-old fetus was dissected into intestine, liver, brain and residual tissue. Nonacid glycosphingolipid fractions were prepared from the tissues. Glycolipid characterization was carried out using thin layer chromatography immunostained with monoclonal antibodies and bacteria and by 1H NMR spectroscopy and mass spectrometry. In the placental fraction substantial amounts of globotetraosylceramide (P-antigen) and globotriaosylceramide (Pk-antigen) were identified. In contrast, the fetuses contained only trace amounts of these structures, as revealed by immunostaining. These results indicate that the primary target for the antibodies of the anti-Tja serum is the placenta tissue, resulting in termination of the pregnancy.

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Uropathogenic Escherichia coli strains designated as ONAP, based on their 0 negative A positive agglutination of human Pi erythrocytes, were shown to prefer the globo-A glycolipid as a receptor structure. The dependence on both the A terminal and the globoseries chain was confirmed by agglutination of human AP,, but not Ap or OP, erythrocytes and by binding to the globo-A glycolipid on TLC plates. Neither Gala1 +4GalB nor the A trisaccharide GalNAcul+ 3(Fucal+2)Gal~ alone functioned as receptors. The bacteria thus appeared to recognize an epitope resulting from the combination of the terminal and internal structures.