An enzyme basis for blood type A intermediate status.

The blood type A is known to be subclassified as A1, A2, and A1-A2 intermediate (Aint), depending upon red cell agglutinability with anti-A1 and anti-H lectins. Approximately 80% of the blood group H-sites remained unglycosylated in type Aint erythrocyte membranes. Plasma from Aint individuals contains a special blood group GalNAc transferase (UDP-GalNAc:2''-fucosylgalactoside-alpha-3-N-acetylgalactosaminyl transferase), which is different from the enzyme in A1 plasma and the enzyme in A2 plasma. A1-enzyme has strong affinity to UDP-GalNAc and 2''-fucosyllactose, A2-enzyme has low affinity to both substrates, and Aint-enzyme has strong affinity to UDP-GalNAc and very low affinity to 2''-fucosyllactose, which is a soluble analog of the H-substances. The low degree of glycosylation of the blood group H-sites due to the low affinity of Aint-enzyme with the H-substances can account for the lower A activity and higher H activity in Aint red cells than in A1 red cells. The blood group A allele can be subdivided into three common alleles, A1, A2, and Aint, each controlling the formation of different types of blood group GalNAc transferases.     

Family study and frequency of blood group with strong B transferase accompanied by decreased A and H antigens

Subgroups of type A blood, named A1, A2, and A1-A2 intermediate (Aint), are specifically characterized by their peculiar A alleles and have their own A1-, A2- or Aint-forms of alpha-N-acetyl-D-galactosaminyltransferase (A-transferase). It is known, however, that certain type A2B persons exhibit A1-transferase. The reason may be an unusual alpha-galactosyltransferase (B-transferase). This strong B-transferase competes with A-transferase for the substrate, H antigen, so as to decrease the A and H antigens on the red cells. We studied this blood group over three generations and found that the strong B-transferase is, in fact, inherited with the B gene and is dominant over normal B-transferase. In AB blood groups in Tokyo, the frequency of people with a strong B-transferase is 5% for A1B and 22% for A2B. This enzyme does not always cause weak H or A antigens.     

Interaction between haptoglobin subtypes and AB0 blood groups in a Bengalee population

Blood samples from 621 individuals of a Caste Hindu Population from West Bengal (India) were investigated in an attempt to find out an association between the AB0 blood groups and Haptoglobin (HP) subtypes. AB0 blood grouping was done on the basis of the agglutination test with standard anti-sera. Haptoglobin subtyping only for the HP*1 allele was done by Polyacrylamide Gel Electrophoresis (PAGE). A significant association was found with a significantly lower HP*1S allele frequency in blood group 0 versus other AB0 blood groups. A comparatively higher allele frequency of HP*1S was found in this population sample. An inverse relationship between HP*1S and HP*2 has been revealed in each blood group. It appears that the major portion of HP*1 alleles in the A, B, and AB blood groups belongs to the HP*1S allele compared to that of the 0 blood group.     

The existence of atypical blood group galactosyltransferase which causes an expression of A2 character in A1B red blood cells

It is generally accepted that the blood group subtypes A1 and A2 expressions are controlled by two different blood group N-acetylgalactosaminyl-transferases, that is, A1-enzyme and A2-enzyme, respectively, and that the two types of enzymes are governed by the allelic A1 and A2 genes. The observed frequencies of blood types in Caucasians are compatible to this model. However, the subtype A2 character is far more frequently observed in AB red cells than in A red cells in some black and Oriental populations. Two black blood samples with phenotype A2B contained A1-enzyme, but not A2-enzyme, and exhibited several times higher B-enzyme activity than control AB and B blood. The kinetic properties, that is, pH-activity profile and Km for UDP-Gal, of the B-enzyme from these two A2B subjects differed from that of control B-enzyme. In these two cases, therefore, the A2 character was not caused by the subactive A2-enzyme, but because of an insufficient formation of the A-substances in red cell membranes presumably caused by the competition between the A1-enzyme and the super active atypical B-enzyme at the common H-sites. The results suggest that the B gene can be subdivided into usual B1 and atypical B2, and that not only A2B subjects but also A1B2 subjects could express A2 character in their red cells. The B2 gene may be common in certain black and Oriental populations.     

The Cis AB complex of the ABO system]

Members of six unrelated families from Japan, France, Belgium and Poland were studied in parallel. Major immunological features characteristic of the phenotype produced by the Cis AB complex are the following: 1) The red cell A reactivity is close to normal, is beyond the values of agglutination scores by Helix and by anti-A from B; likewise, with percent agglutination measurements, A reactive appears hiher than that of A2B cells; one sample only is slightly detected by anti-A from Dolichos. 2) The B reactivity, on the contrary, is lower than that of normal AB cells. A single sample is detected by anti-B from A1. All samples are well detected by anti-B from AW, Aend, Ax, Am but none is detected by anti-B from ABx, Cis AB, or by an auto-anti-B. Under standard conditions, percent aggutination is around 80, very close to that of normal AB cells, thus differentiating Cis AB from AB3 (some of which only reach this figure), and from ABx which are very far from this value. 3) An abnormally high reactivity to anti-H antibody is observed, higher than that of normal A2B, similar to that of A2 red cells. 4) Among secretors, A substance is found to be normal or in excess, H substance is in excess, while B substance is only detected by Cis AB red cells inhibition. 5)An anti-B antibody was identified in the samples studied; however, we recently received from Germany a Cis AB samples, the serum of which did not contain anti-B antibody. By these main characteristics, the studied samples seem to be identical; however, agglutination kinetics and thermodynamic methods show that they differ by their reaction with a same anti-B antibody in standard conditions. The reactive structures of the various samples are indeed different from one family to another. The main point is that identical values were observed in all samples within a same family. Thus, the various Cis AB can be considered as different families mutants.     

Maternal IgG anti-A and anti-B titres predict outcome in ABO incompatibility in the neonate

Hemolytic disease of newborn (HDN) is an alloimmune hemolytic disease which occurs due to red blood type incompatibility between mother and fetus. An AB blood type neonate was admitted to Shengjing hospital with severe anemia. Major crossmatch incompatibility was found with some random donors. Serological tests were administered to the neonate and his parents. The mother was B blood type, while the father was AB blood type. The neonate's direct antiglobulin test (DAT) was negative, but the elution test was positive with A₁ cell and negative with A₂ cell. Titers 64 anti-A₁ and 2 anti-A in the mother's serum were detected after treated by dithiothreitol (DTT). The mother's red cells showed a weak agglutination with anti-A under microscopy. The neonate was diagnosed with HDN. After phototherapy and A₂B red blood cell (RBC) transfusion, the neonate was discharged with a recovery of his hemoglobin and physiological index. This study describes a rare case of HDN caused by anti-A1 allo-antibodies.     

Imbalance of blood group A subtypes and the existence of superactive B gene in Japanese in Hiroshima and Nagasaki.

Blood type A can be classified into subgroups A1, A2, and A1-A2 intermediate on the basis of serological criteria. An excess of A2B over A2, noted in some black populations and among the Japanese, though not in caucasoids, is inconsistent with the classical Mendelian mode of inheritance of the allelic A1 and A2 genes. Characterization of the enzymatic properties of the blood group A and B enzymes in the serum has shown that serological A2B blood of some blacks contains A1 enzyme and a superactive B* enzyme. An excess of A2B found in a study of over 15,000 residents of Hiroshima and Nagasaki prompted investigation of the characteristics of the A and B enzymes in 60 blood samples, 37 from individuals in 13 unrelated families and 23 from other unrelated individuals in the two cities. Among 27 unrelated individuals whose blood types were unequivocally classified serologically as A2B, 15 were confirmed as A2B enzymatically; eight contained A1 and B* enzymes, not A2 or B enzymes, thus being A1B*; two contained Aint and B* enzymes, thus being AintB; and results for the remaining two were ambiguous. Hiroshima differs from Nagasaki in the frequency of the A2B serological type and also in the occurrence of the B* enzyme, Nagasaki having a higher proportion of both. If one considers those cases in which family study was possible, the transmission of the B* enzyme appears to be compatible with the Mendelian mode of inheritance.(ABSTRACT TRUNCATED AT 250 WORDS)     

血型检测用反向定型试剂的研制

将正常的红细胞在特定条件下用甲醛处理,使红细胞膜固定但不影响膜表面糖蛋白血型抗原的活性。采用与正向定型相同的平板凝集试验方法,４０６０份血样正向和反向定型结果完全一致。经稳定性观察９０天,处理后的红细胞与相应抗体的凝集性能未见明显改变。实验结果表明本文介绍的红细胞试剂可用于ＡＢＯ血型鉴定的反向定型试验。     

Genetic mechanism of blood group (ABO)-expression

It has generally been believed that human blood group ABO is controlled by allelic ABO genes. However, this hypothesis has not yet been experimentally proven, and other possibilities such as the non-allelic gene model and the regulatory gene model for ABO locus have also been proposed. The genetic mechanisms of many unusual blood group expressions remain unanswered. Purification of human blood group N-acetylgalactosyltransferase (A-enzyme) which synthesizes A-substance, and blood group galactosyltransferase which is responsible for synthesis of B-substance, allows us to resolve these problems from an immuno-biochemical approach. It was found that rabbit antibody against-A-enzyme completely neutralized not only A-enzyme but also B-enzyme activity. Moreover, plasma from blood type O subjects contained an enzymatically inactive but immunologically cross-reactive material (CRM). Plasma from heterozygous AO and BO subjects also contained CRM, but plasma from homozygous AA and BB subjects did not contain CRM. These facts led us to conclude that the ABO genes are allelic in the strict sense, refuting other genetic models for ABO locus. Genotypes of phenotype A and B subjects can be unequivocally determined by examining the presence or absence of CRM in their plasma. Mechanism of the unusual blood group inheritance of Cis-AB (i.e., AB and/or O childbirth from AB X O parent) was elucidated by examining properties of the A and B enzymes, CRM in their plasma, and separation of active enzymes and CRM by affinity chromatography. It became clear that Cis-AB expressions in one family was due to unequal chromosomal crossing-over producing a single chromosome with the genes for A and B enzymes. In contrast, in the other two unrelated families, the Cis-AB expression was due to a structural mutation in A or B gene producing a single abnormal enzyme which was capable of transferring both GalNAc and Gal to H-substance. Mechanism of very weak B expression in a family with A1Bm character was studied. Plasma enzyme activity and kinetic characteristics of B-enzyme from the subjects was not different from that of normal. However, the A1Bm red cells contained a large amount of unoccupied H-sites which can be galactosylated in vitro and become B active. Examination of membrane components by isoelectric focussing revealed that blood group components of the A1Bm membranes were distinctively different from that of the usual membranes. Consequently, the weak B expression is not due to direct mutation of ABO locus, but due to a secondary consequence of genetic abnormality of a membrane component (or components) associated with blood group substances.     

The incidence and features of serological ABO subgroups among one million blood donors in Beijing

This study aims to determine the incidence of serological ABO subgroups from a large-scale database, along with the features of blood samples with serological ABO discrepancies. The serological ABO results of one million individuals were randomly sampled from a blood donor database in Beijing between 2009 and 2010. All samples were diagnosed by serological reverse and forward ABO typing using an automatic analyzer. The proportions of the normal ABO types were 27.28%, 31.57%, 30.56%, and 10.16% for blood types A, B, O, and AB, respectively. In samples in which ABO discrepancies or obvious weak agglutinin were identified in the forward or reverse typing, further tests to analyze the ABO subgroup were conducted. The overall incidence of ABO subgroups was 0.047%, with 14 ABO subgroups observed: A2, A3, Ax, Am, Aint, Aend, B2, B3, Bx, Bm, Bel, B(A), cisAB, and AB^h. In conclusion, this study revealed the exact normal ABO and subgroup distributions in the general, healthy population of Beijing using samples from a blood donor database.     

The ABO blood groups and the B atypical gene in Brazil: a serologic and population genetic approach to the issue.

The fit to Hardy-Weinberg equilibrium is improved if an atypical B allele is assumed to exist along with the A1, Aint, A2, B, and O genes in the ABO system. This atypical B allele accounts for 37% or so of the total B gene frequency in both Brazilian whites and blacks.     

Incidence of ABO(H) blood group variants among the Bulgarian population.

The result of a screening of ABO (Hh) variants after investigating the blood group of 106,980 persons are presented. The Ax variant is registered most frequently among the Bulgarian population. As a whole the frequencies of ABO blood group variants Ax, Ael, A3, Aend and Am among the Bulgarian population are similar to that established by other authors among the French population and nearly twice as high as among the population of Bombay. The group of H-deficient phenotypes includes AA1Xh, AHm, OHm variants. Their frequency is significantly lower when compared with the frequency of AHm and OHm variants among the population of Thailand. Variants A1 and Aint with unusually high H-content are classified as A1H, A1Hint, Aint H and integrated as a category of H-excess phenotypes. Their incidence among the Bulgarian population is significantly lower than that registered among Maharastrian, South African Bantu and Indian.     

Abnormal blood group galactosyltransferase in blood type A1B-subjects whose sera contain anti-B agglutinin

Summary A blood type A₁B female, whose plasma agglutinates B red blood cells from other subjects but not her own, was found. Her sister with blood type A₁B (sister-1) exhibited the same peculiarity. The agglutination titer of red cells from these two subjects is lower than that of normal B. Her father is blood type B, and his plasma did not agglutinate B red cells from other subjects and his own. Her mother and another sister (sister-2) were usual blood type A₁. Blood group galactosyltransferase (B-enzyme) activity of plasma from the propositus, sister-1, and their father was very low. Km for 2-fucosyllactose of B-enzyme of these subjects was 1.3 mM, which was more than two times higher than that of the normal value. Km for UDP-Gal was similar, but the pH-activity profile differed for the two enzymes.Red cell membranes from her father contained about 70% ungalactosylated H-sites, whereas, virtually all H-sites are galactosylated in the usual B red cell membranes. The blood group ABH components are known to be heterogeneous. Because of the abnormal B-enzyme with low activity and low substrate affinity, some H components might not be galactosylated, particularly in A₁B cases (i.e., the propositus and her sister-1), due to competition by A₁ enzyme. The lack of certain B components is likely to be the cause of the existence of the anti-B agglutinin in their sera.     

Biochemical characterization of the feline AB blood group system

The biochemical nature of the feline AB blood group system was characterized by analysing red blood cells from homozygous (genotype A/A) and heterozygous (A/B) type A, type B (B/B), and type AB cats. High performance thin layer chromatography (HPTLC) of red cell gly-colipids revealed that specific neuraminic acids (NA) on gangliosides, containing ceramide dihexoside (CDH) as a backbone, correlated with the feline AB blood group antigens. Although disialogangliosides predominated, mono- and trisialogangliosides were also isolated. B cats expressed solely N-acetyl-NA (NeuNAc) on these gangliosides. In addition to expressing N-glycolyl-NA (NeuNGc) containing gangliosides, A red cells have gangliosides with only NeuNAc or mixtures of both NA. HPTLC profiles of disialogangliosides from homozygous and heterozygous A cats differed slightly in the quantity of disialogangliosides. Equal amounts of NeuNAc and NeuNGc containing disialogangliosides, as well as two intermediary forms, were recovered from AB erythrocytes. Analysing disialogangliosides from red cells belonging to 17 genetically related cats, we consistently obtained the expected disialoganglio-side profile, based on blood typing and pedigree information. SDS-PAGE of red cell membrane proteins and blotting with Triticum vulgaris, a lectin recognizing NeuNAc, revealed glycoproteins of approximately 51, 53, and 80 kD in B and AB cats but only a faint band of approximately 53 kD in A cats. By haemagglutination, Triticum vulgaris could also distinguish different blood types by specifically binding to B and AB cells. Flow cytometry showed that more anti-B bound to B cells than anti-A bound to A cells. Although AB cells had a broad range of fluorescence when compared to the profiles seen with A and B cells, the mean fluorescence with AB cells was half of that seen with A or B. These results further characterize the antigens determining the feline AB blood group system illustrating differences between A, B and AB cats, and between homozygous and heterozygous A cats.     

野花生豆凝集素的纯化和性质

用猪胃粘蛋白-Sepharose 4B作亲和吸附剂,可从野花生豆(Crotalarta mucronata)的种子中分离纯化出对人类A型血专一凝集的凝集素。该凝集素可用pH30.,Gly-HCl-1mol/L NaCl溶液解吸附。纯化的凝集素在PAGE或SDS-PAGE中均显示单一蛋白带,表明凝集素分子内只有一种亚基。用SDS-PAGE测得其亚基分子量为49,000。氨基酸组成分析表明,该凝集素富含甘氨酸和谷氨酸,不合甲硫氮酸。纯化的野花生豆凝集素(简称CML)含有4.11％的中性糖。它对人A型血细胞有强烈凝集作用,对AB型血有弱凝集作用,但对B型和O型血均不凝集。其对A型血细胞的凝集作用可被N-乙酰半乳糖胺抑制,但对AB型血则无抑制作用。CML是一个促有絲分裂原,对人外周血中淋巴细胞有促有絲分裂作用。     

Serological and molecular analysis of ABO and Rh blood group chimeras

The serological examination, blood transfusion strategies and the molecular analysis to blood group chimera were conducted to demonstrate existent of chimera in blood group. The blood grouping of ABO or/and RhD, newborn red blood cells separated by capillary centrifugation. Aabsorption tests and DTT treated agglutination erythrocyte tests were implemented in four patients. Further molecular biological research was conducted on one patient''s sample. The results showed that for patient 1: ABO blood group was AB/B chimera, Rh blood cells contained the RhCE chimera gene; Patient 2: Rh blood cells contained the RhD chimera gene; Patient 3: ABO blood group was AB/B chimera, Rh blood cells contained the RhD chimera gene; Patient 4: ABO blood group was O/B chimera, Rh blood cells contained the RhCE chimera gene. The study suggests that the individuals categorized as chimeras are likely to be more common than existing literature reports. According to the serological tests, in the absence of a history of recent blood transfusion or disease to cause reduced antigen, the phenomena of hybrid aggregation of the ABO and Rh blood system were the main feature. In terms of transfusion strategy, the selection of ABO and Rh blood groups should be depended on the group of cells with more antigens.     

Genetic Characterization of Human Populations: From ABO to a Genetic Map of the British People

From 1900, when Landsteiner first described the ABO blood groups, to the present, the methods used to characterize the genetics of human populations have undergone a remarkable development. Concomitantly, our understanding of the history and spread of human populations across the earth has become much more detailed. As has often been said, a better understanding of the genetic relationships among the peoples of the world is one of the best antidotes to racial prejudices. Such an understanding provides us with a fascinating, improved insight into our origins as well as with valuable information about population differences that are of medical relevance. The study of genetic polymorphisms has been essential to the analysis of the relationships between human populations. The evolution of methods used to study human polymorphisms and the resulting contributions to our understanding of human health and history is the subject of this Perspectives.THE A, B, and O blood types of the ABO blood group system were first described by Landsteiner in 1900, the year of the rediscovery of Mendel’s work. Landsteiner had set out to see whether the sorts of differences between species that had been detected by serological methods might also occur within species (see Owen, 2008). The experiment was very simple: mix the red blood cells of one person with the serum of another and do this pairwise for a number of people. To his surprise, he found that certain combinations of serum and red cells led to clumping or agglutination of the red cells. Based on the resulting patterns of agglutination of the red cells, three types of serum and red cells were identified: A (which agglutinates only B cells), B (which agglutinates only A cells), and O (which agglutinates both A and B cells). [Landsteiner did not at first observe AB serum (which agglutinates neither A or B cells) because of the small size of his sample.] These types seemed to be intrinsic to the individual and did not change with time or, for example, the presence of infections. They were, as we now know, the inherited characteristics of an individual’s red blood cells. Landsteiner’s work, together with many subsequent developments, meant that blood transfusions became possible and eventually much safer. In addition, this simple but fundamental analysis was the initial stimulus for all subsequent studies of the frequency of genetic variation in different human populations and the use of genetic variants for characterizing genetic differences among humans.     

An auto-anti-b in an a1b person. Serological studies.

The serum of a patient (Mr. Lat) with the regular blood group A1 B contains an anti-B reacting with all cells having a B antigen except Bx and cis AB. The anti-B reacts at 4 degrees C and occasionally at room temperature as shown by agglutination, absorption-eluction and by thermo-dynamic assays. The antibody is regarded as an irregular autoantibody belonging to the group of the so called "suppressed" or "latent" antibodies.     

Acquired B antigen: further studies using synthetic oligosaccharides

The reactivity of acquired-B red cells with various antisera has been investigated by agglutination inhibition assays using four trisaccharides obtained by chemical synthesis. Two of these had the structure GalNAc alpha 1-3 (LFuc alpha 1-2). Gal and Gal alpha 1-3 (LFuc alpha 1-2) Gal which are characteristic of the A and B determinants respectively and were indeed strong inhibitors of human anti-A and -B antibodies. The other two sugars denoted B-OAc and B-NH2 are derivatives of the B-trisaccharide by substitution of the hydroxyl group on carbon-2 of the alpha-galactose residue with the O-acetyl group (B-OAc) or the amino group (B-NH2) respectively. We have shown that both B and B-NH2 trisaccharides inhibited strongly the agglutination of acquired B red cells by the anti-B reagents (crude or affinity purified) whereas sera containing "anti-acquired B" agglutinins were specifically inhibited by B-NH2 but not by the A, B or B-OAc structures. We have also shown that the agglutination of Tk-activated erythrocytes by the BS-II lectin is specifically inhibited by N-acetylglucosamine but not by B, B-OAc or B-NH2 structures. These results and the observation that anti-acquired B agglutinins cannot be adsorbed on Tk red cells suggest that (i) the "B-like" and the "acquired-B" determinants share a common structure best represented by B-NH2 and (ii) Tk and "acquired-B" antigens are not identical.     

南方鲇血型的初步鉴定

本研究旨在通过观察南方鲇血清与其红细胞的交叉反应以鉴定南方鲇的血型.实验结果表明:南方鲇的血清与同种其他个体的红细胞进行交叉反应时均未出现凝集现象,这表明南方鲇可能不存在血型或南方鲇具备血型但血清中相应的凝集素含量不足.以南方鲇的红细胞为抗原免疫日本种大耳白兔制备的抗血清与南方鲇的红细胞进行交叉反应,出现了不同程度的凝集反应,这表明南方鲇存在血型.据上述两个实验结果可以推断,南方鲇可能存在4种血型,分别命名为NA、NB、NAB和NO型;同时也证实,在鉴定南方鲇血型的研究中,通过制备抗血清与红细胞进行交叉反应的方法更为可靠.