Errors in detection of subgroups in the ABO blood group system]

In the ABO blood group system, several subgroups have been described based on: 1) the difference of reactivities of the red cells with anti-A, anti-B, anti-A1, and anti-H, 2) the presence or absence of anti-A, anti-B, anti-A1, anti-H, and anti-HI in serum, and 3) the presence of A, B, H substances in the saliva of ABH secretors. Subgroups of A are more frequent in Caucasians than in Japanese, while those of B are more frequent in Japanese. Both the red cell typing (testing red cells for A and B antigens) and serum typing (testing the antibodies in the serum against red cells of known ABO groups) are important to identify and not to overlook these ABO subgroups. When transfusion is required in individuals with these subgroups, compatible blood products must be selected according to the presence or absence of antibodies active at 37 degrees C.     

The high-molecular-weight human mucin is the primary salivary carrier of ABH, Le(a), and Le(b) blood group antigens

Because many bacteria interact with the carbohydrate portions of receptor molecules, factors controlling glycosylation probably influence the ability of salivary components to mediate bacterial adherence/clearance. Important sources of diversity in glycosylation are the ABO, secretor, and Lewis genes, which code for glycosyltransferases that add specific sugar sequences to the termini of carbohydrate chains of glycolipids and glycoproteins. We identified, by Western blotting, salivary glycoproteins carrying the ABH and Le(a) or Le(b) antigens. Samples of whole, unstimulated saliva were obtained from 19 subjects whose blood group was determined by agglutination of red blood cells with specific antisera. After centrifugation, the samples were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted onto nitrocellulose. Glycoproteins carrying blood group antigens were identified by staining the blot with monoclonal antisera specific for the A, B, H, Le(a), or Le(b) antigens. The most intensely staining component from all the samples migrated at the same position as the high-molecular-weight mucin. Saliva samples from the nonsecretors contained only the Le(a) antigen. Samples from the secretors contained one or more of the ABH antigens and, variably, the Le(b) antigen. In all cases, the salivary blood group antigens corresponded to those found on the red blood cells of the same subject. The functional consequences of the expression of blood group antigens on the high-molecular-weight mucin are not known, but their presence could modulate the adherence of certain oral microorganisms that interact preferentially with this molecule.     

Hemagglutination inhibition studies of water soluble blood group substances recovered from the erythrocytes of classical Bombay Oh subjects

Using ethanol and acetone fractionation to isolate soluble blood group substances from red blood cells, 'Bombay' Oh bloods were found to contain variable amounts of concealed H substance. The IgG variety of anti-H in 'Bombay' bloods has a greater affinity for these substances than the IgM variety of anti-H. Group O parents of 'Bombay' Oh subjects were found to have normal levels of H substance, indicating that individuals heterozygous for a recessive suppressor gene 'x' synthesize it normally. In the 'Bombay' family studied, Lewis determinants were abnormally expressed in two members. Lewis activity was detected in the soluble extracts of their red blood cells but not by the direct agglutination test. Further tests using known Le(a-b-) types are necessary to determine whether these findings are linked to the 'Bombay' Oh phenomenon.     

Detection and clinical features of hepatitis C virus type 6 infections in blood donors from Hong Kong

The genotype distribution of hepatitis C virus (HCV) was investigated in 212 viraemic blood donors from Hong Kong. A subset of the samples was investigated using three different genotyping assays to establish the accuracy of each in this population. These assays were restriction fragment length polymorphism (RFLP) of amplified 5' noncoding region (5'NCR) sequences, RFLP of the core region, and a serotyping assay using peptides from two antigenic regions of NS4. Genotypes detected in Hong Kong blood donors were 1a (6.2%), 1b (58.8%), 2a (1.4%), 2b (1.4%), 3a (1.9%), and 6a (27.0%). All genotyping assays produced concordant results. No evidence was obtained for the presence of type 6 group variants recently identified in Southeast Asia, other than type 6a. A serotyping assay based upon the detection of type-specific antibody to epitopes in NS4 produced similar results to the genotyping assays (98% concordance), but a reduced sensitivity (75%) compared with genotyping methods. Sequence variation in NS4 was not the cause of the reduced rate of detection of type 6 antibody in this population. Eighty-four percent donors infected with type 6a were male, compared to 75% donors infected with type 1b. The median alanine transaminase (ALT) level in type 6 infected donors was lower than in type 1b, (43.8 and 51.1 U/l, respectively) although these values were not statistically significant (P = 0.094). There was no significant difference between the ages of donors infected with types 1b and 6a. Risk factors for HCV infection in the blood donors included blood transfusion, intravenous drug abuse, and tattooing. A significantly greater number of donors infected with HCV-6a reported a history of drug abuse (66%) than donors infected with HCV-1b (7%).     

Donor hepatectomy for living-donor liver transplantation

Between September 1993 and November 1996, donor hepatectomy was performed in 22 living donor liver transplantation at Queen Mary Hospital, Hong Kong. In these donor operations, 7 extended right lobe grafts, 6 extended left lobe grafts and 9 left lateral segment grafts were obtained. The technique of donor operations consisted of initial hilar dissection, mobilization of the liver lobe, transection of the liver using ultrasonic dissector (without inflow or outflow vascular occlusion) at a plane on the left side of the middle hepatic vein for an extended right lobe graft, on the right side of the middle hepatic vein for an extended left lobe graft or on the right side of falciform ligament for a left lateral segment graft. The median blood loss was 775 ml. Complications occurred in 2 donors: one had incisional hernia and the other had biliary stricture. Both were treated successfully by re-operation. Currently all donors are well with completely normal liver biochemistry.     

Cell electrophoretic mobility and glycerol lysis of human erythrocytes in various diseases

Using an automated cell electrophoresis system equipped with an image processor, we studied electrophoretic mobilities of erythrocytes of healthy donors and of patients suffering from systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), hypergammaglobulinemia and diabetes mellitus (DM). On average, erythrocytes from SLE patients showed mean electrophoretic mobilities (EPM) which were significantly lower (p < 0.005) than the EPM of red blood cells of normal donors. Evaluation of mean EPM and standard deviations revealed that three groups of SLE patients could be distinguished regarding the electrophoretic behavior of their erythrocytes. Some patients had red blood cells with normal EPM, others had erythrocytes with significantly reduced EPM, and a third group appeared to have both kinds of erythrocytes. In addition, erythrocytes of various SLE patients showed enhanced resistance to lysis by glycerol and their membranes contained less quantities of band 3 proteins.     

Immunochemical characterization of anti-H monoclonal antibodies obtained from a mouse immunized with human saliva

Three IgM class anti-H monoclonal antibodies (1E3, 1E5 and 3H1) were obtained from a BALB/c mouse immunized with human O type saliva. These antibodies were found to agglutinate red cells from O group and A and B subgroups but not from Bombay and para-Bombay individuals whose H antigen was barely detected by anti-H reagents. The agglutination reactions of these antibodies were inhibited by H antigens from human tissues. It was also demonstrated that both 1E3 and 3H1 reacted with H disaccharide (Fuc alpha 1-->2Gal beta), H type 1 (Fuc alpha 1-->2Gal beta 1-->3GlcNAc beta), H type 2 (Fuc alpha 1-->2Gal beta 1-->4GlcNAc beta), H type 3 (Fuc alpha 1-->2Gal beta 1-->3GalNAc alpha) and H type 4 (Fuc alpha 1-->2Gal beta 1-->3GalNAc beta) but not with Lea (Gal beta 1-->3[Fuc alpha 1-->4]GlcNAc beta), Leb (Fuc alpha 1-->2Gal beta 1-->3[Fuc alpha 1-->4]GlcNAc beta), X (Gal beta 1-->4[Fuc alpha-->3]GlcNAc beta) or Y (Fuc alpha 1-->2Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc beta). On the other hand, 1E5 was found to react with H type 1, H type 2, Leb and Y. Because of the unique reactivities against various fucosyl linkages these monoclonal antibodies could be useful not only as anti-H reagents but also as reagents for the structural analysis of fucosylated glycoconjugates.     

Prevalence and genotypes of alpha- and beta-thalassemia carriers in Hong Kong -- implications for population screening

BACKGROUND: The thalassemias are common in southern China. We determined the prevalence of heterozygous carriers of these genetic disorders in Hong Kong and assessed the feasibility of a community-based screening program. METHODS: An educational and screening program for the thalassemias was carried out in three high schools with a total of 2420 students. Seventy-five percent of the students agreed to undergo screening, which consisted of blood counts, hemoglobin electrophoresis, serum ferritin measurements, and DNA analyses. RESULTS: Of the 1800 blood samples tested, 150 (8.3 percent) had microcytosis (mean corpuscular volume, <80 microm3). Ninety students (5.0 percent) were carriers of alpha-thalassemia, of whom 81 (4.5 percent) were carriers of the Southeast Asian type of deletion, in which both alpha-globin genes on the same chromosome 16 are deleted. Sixty-one students (3.4 percent) were carriers of either beta-thalassemia or the mutation coding for hemoglobin E. Six students were carriers of both alpha- and beta-thalassemias. On the basis of these figures, the estimated numbers of pregnancies in Hong Kong in which the fetus is at risk for homozygous alpha-thalassemia and beta-thalassemia major or intermedia are 145 and 80 per year, respectively. In Hong Kong the actual numbers of women referred for prenatal diagnoses of these disorders are approximately 95 and 40 per year, respectively. CONCLUSIONS: Despite the availability of hospital-based screening and prenatal diagnosis for many years in Hong Kong, many women carrying fetuses at risk for thalassemia are not referred for genetic counseling. A community-based program of education, screening, and counseling is needed in Hong Kong and southern China.     

Cohort study of HIV infection among drug users in Ruili, Longchuan and Luxi of Yunnan Province, China

Among Hong Kong Chinese blood donors, 99.71 percent were found to be D+. Of these, 55.02 percent were of the phenotype CCDee. The Du phenotype was found to be present in 0.016 percent. Among the 0.27 percent who were apparently D-, 0.079 percent were of the Del phenotype, while the remaining 0.19 percent were "true D-," as defined by a nonreactive eluate obtained by an adsorption and elution procedure using anti-D. The ccdee phenotype constitutes 56.77 percent of the "apparent D-" and 80.24 percent of the true D-. Data show that anti-D rarely occurs in Hong Kong Chinese, and it is postulated that this could be due to the presence of a very weak form of the D antigen among many of those who appear to be D-.     

Race and intra-urban migration

Human blood group O cells were converted into B-active cells by incubation at either 4 degrees or 37 degrees with uridine diphosphate D-galactose and unfractionated serum from the Japanese tortoise (Clemmys japonica). The specificity of the converted cells was tested by their reactions with human anti-B, anti-A and rabbit anti-B sera. Under the conditions used, Bombay (Oh) type cells were not converted, and group-O foetal cells possessing a few H antigenic sites were only weakly converted into B-active cells. In addition, the agglutination titre of the converted cells with eel anti-H serum decreased. These results therefore indicate that the conversion depends upon the preference of H-substance on the red cells. The alpha-galactosyltransferase in tortoise serum thus resembles the transferase in human group-B serum and these results suggest that the mechanism of biosynthesis of blood group B substance in the tortoise is similar to that in humans.     

Seroconversion of type B to O erythrocytes using recombinant Glycine max alpha-D-galactosidase

Recombinant alpha-D-galactosidase (rGal) from soybean (Glycine max) hydrolyzed the immunodominant alpha-D-galactose residue from the B epitope of red blood cells. This converted type B erythrocytes to type O which are "universally" transfusable. Type B red blood cells were obtained from four different donors and enzymatically converted. Cell function parameters, including red cell indices, pH, methemoglobin, carboxyhemoglobin, osmotic fragility, hemolysis, 2,3-diphosphoglycerate, cholinesterase, ATP, and antigen typing of treated cells were compared to controls. These pilot studies indicate that rGal could have potential biotechnical application in the production of universally transfusable red blood cells.     

Presence of human herpesvirus 6 variants A and B in saliva and peripheral blood mononuclear cells of healthy adults

Saliva and peripheral blood mononuclear cells (PBMCs) from 44 healthy young adults were tested for human herpesvirus 6 variants A and B (HHV-6A and -6B) DNA by a sensitive nested PCR. HHV-6B infection was ascertained in 98% of the subjects, and 95% were found to excrete variant B in their saliva. HHV-6A was found in the PBMCs of 16%, but was not detected in saliva samples.     

Hemolytic reaction due to graft-versus-host (GVH) antibody production after liver transplantation from living donors: report of two cases

Among 27 patients who received minor ABO-incompatible partial liver transplantations and 19 who received major ABO-incompatible partial liver transplantations from living donors, 2 developed hemolytic anemia within 2 weeks after transplantation. These 2 patients had received livers from their living fathers whose blood type was ABO-incompatible. B-to-A transplantation was performed in patient 1 and O-to-B transplantation was performed in patient 2. Anti-A IgM and IgG were detected in the serum of patient 1, and anti-B IgM and IgG were detected in the serum of patient 2. These antibodies were eluted from the red blood cells of the patients. The coexistence of donor-specific DNA in the peripheral blood of the patients proved that they had chimerism, and graft-versus-host antibody production due to passenger B lymphocytes in the donor's liver was subsequently confirmed.     

Serological diagnosis of influenza B virus infection: comparison of an enzyme-linked immunosorbent assay and the hemagglutination inhibition test

The sensitivity of an enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to influenza B virus was compared with that of the hemagglutination inhibition test on acute- and convalescence-phase sera obtained from adults and children infected with influenza B virus. Two whole virus, tissue culture-grown antigen preparations were used in the ELISA, influenza B/West Virginia/81 and influenza B/Hong Kong/72. Four antigens were used in the hemagglutination inhibition test. These included the tissue culture-grown whole virus antigens that were used in the ELISA. In addition the standard egg-grown antigens, influenza B/Singapore/79 and influenza B/Hong Kong/72, were included for comparison. The ELISA antibody titer was significantly correlated to the hemagglutination inhibition antibody titer, and 10 of 10 adults and 17 of 21 children infected with influenza B had fourfold antibody increases as detected by ELISA with either antigenic type of tissue culture-grown whole virus. Increases in geometric mean antibody titers of 16- to 71-fold were detected by ELISA. Increases in geometric mean antibody titers of 3- to 10-fold were detected by hemagglutination inhibition depending on the type of antigen utilized. We found that ELISA with whole virus antigens was a sensitive and specific test for the detection of antibody to influenza B virus.     

ABH blood group antigen significance as markers of endothelial differentiation of mesenchymal cells

The expression pattern of A, B and H blood group antigens was evaluated by staining frozen sections with specific monoclonal antibodies developed by us and using the indirect immunoperoxidase method. The expression of blood group antigens was ubiquitously upregulated in the endothelial cells of fetal organs. In the process of their differentiation to endothelial naive embryonic mesenchymal cells expressed cytoplasmic ABH antigens. They were assumed as products of the activation of the respective genes. ABH antigen expression was considered as suggestive evidence for the assumption that blood group antigens could serve as early immunomorphologic markers of endothelial differentiation of mesenchymal cells, thus specifying the location of future blood vessels. Extending the conceptual framework of blood group antigens' significance we consider them as being possibly involved in the process of fetal morphogenesis.     

An EDTA-associated anti-B agglutinin: the role of ionized calcium

BACKGROUND: It is believed that EDTA-dependent panagglutination is associated with free carboxylic acids that support reactions of rare autoagglutinins. CASE REPORT: An ABO typing discrepancy occurred in an 88-year-old patient. The specificity of his autoagglutinin was demonstrated by panel cell study and absorption tests using normal donors' red cells or immunoadsorbents coated with A, B, or O substances. Inhibition assays were performed to determine whether the autoagglutinin was inhibited by ionized calcium or carboxylic acids. The autoagglutinin had anti-B specificity when tested in the presence of EDTA. It was neutralized by group B secretor saliva and adsorbed by crystalline silica coated with simple B substances with or without EDTA, although it was absorbed by group B red cells only in the presence of EDTA. The agglutinating activity was stronger at 25 degrees C (titer 64) than at 37 degrees C (titer 16) and was destroyed by treatment of the serum with dithiothreitol, which suggests that the autoagglutinin is IgM. This activity also appeared in the patient's serum after dialysis and in an eluate obtained after adsorption with simple B substances, and it was inhibited by the addition of CaCl2 at 0.5 mM or higher concentrations. This suggests that the agglutination is not dependent on EDTA but, rather, on the concentration of ionized calcium. The autoagglutinin failed to react with group B red cells treated with glutaraldehyde for 10 minutes. CONCLUSION: An anti-B autoagglutinin was shown to have caused an ABO typing discrepancy in the presence of EDTA. These results suggest that autoagglutination requires an environment with low levels of ionized calcium, but not the presence of carboxyl groups.     

Hemolytic uremic syndrome as a clinical manifestation of oxidative stress

An examination was made of seventeen children having various stages of the hemolytic uremic syndrome: Stage 1 is the period of an expanded clinical picture of the disease, the patients' condition is grave (anuria, azotemia, severe hemolytic anemia and thrombocytopenia); Stage 2 is the period of recovery. The plasma levels of malonic dialdehyde, dienic conjugates, alpha-tocopherol at the first stage of the disease were considerably higher than the control ones, on recovery there were their reductions though their levels remained higher than the normal levels. The levels of malonic dialdehyde in the red blood cell membranes in ill children were also much higher than those in healthy donors, but at the second stage they decreased, but remained high. The activity of superoxide dismutase in the red blood cells of ill children in the acute period of the disease did not significantly differ from that of donors. At the second stage of the disease there was a significant fall in the activity of red blood cell superoxide dismutase. The activity of catalase in the red blood cells of ill children was thrice higher than in the controls; however, this index decreased during treatment and at the second stage it did not differ from that in the controls. There were no significant differences in the activity of red blood cell superoxide dismutase in donors and ill children. Mechanisms responsible for abnormal plasma and red blood cell peroxidation are considered in the hemolytic uremic syndrome. It is concluded that free radical reactions play a substantial role in the pathogenesis of this abnormality.     

Hydrodynamic Tracking of the Massive Spring 1998 Red Tide in Hong Kong

In subtropical coastal waters around Hong Kong, algal blooms and red tides have been frequently observed over the past two decades. In particular, in March–April 1998, a massive red tide invaded the northeastern and southern coastal waters of Hong Kong. The devastating red tide resulted in the worst fish kill in Hong Kong’s history, the most significant impacts being at the Lo Tik Wan and Sok Kwu Wan fish culture zones on Lamma Island. This work reports the first scientific investigation of the cause of this massive red tide. A calibrated three-dimensional (3D) hydrodynamic model for the Pearl River Estuary, Delft3D, is applied to study the advective transport of red tides. Based on the tidal boundary conditions and the measured wind data for a typical spring season, the 3D flow field is computed and extensive surface drogue tracking performed for releases in different parts of the coastal waters and for different tidal and wind conditions. The results show that a bloom initiated in Mirs Bay (Nan Au or Tap Mun) in the northeastern water would likely be transported to the southern coastal waters under the combined action of tidal current and wind. The computed bloom tracking patterns are generally supported by observations and are consistent with the temporal and spatial patterns of individual fish kill events in the 1998 red tide. We conclude that the major cause of the bloom being transported into the southern waters and East Lamma Channel (and causing the massive fish kill) is the generally strong wind in March–April 1998 and the change in wind direction in early April under almost diurnal tidal conditions. Further, it is most probable that the red tide originated in Mirs Bay rather than from outside Hong Kong. The findings provide a firm basis for environmental and fisheries management.     

The spectrum of chronic lymphoproliferative disorders in Hong Kong. A prospective study

We report the incidence of the chronic lymphoproliferative disorders evolving with leukaemia in Hong Kong. Our findings demonstrate that B cell malignancies are significantly more frequent than mature T cell neoplasms, a picture similar to that seen in Western countries but different from other Eastern countries, eg Japan, where T cell malignancies are more frequent. In contrast to the West, where chronic lymphocytic leukaemia (CLL) is the most common disorder, in Hong Kong there is a clear predominance of B cell lymphomas in leukaemic phase accounting for two-thirds of the cases and particularly those displaying lymphoplasmacytic features or with villous lymphocytes. CLL in Hong Kong has similar clinical and laboratory features to the disease in patients from the West. Distinct disease categories, rare in the West such as the variant form of hairy cell leukaemia and T cell prolymphocytic leukaemia, are also documented. It is unclear whether the differences in prevalence of disease subtypes between Hong Kong and the West relate to different genetic background or environmental factors determinant of the development or progression of the leukaemia. Further studies investigating the genetic/molecular lesions may help to clarify whether the aetiopathogenesis of the lymphoid disorders in Hong Kong is similar to that of Western countries.