Evaluation of Magnetized-Erythrocyte Group Antigens to Detect ABO Antibodies

Screening for IgM titers of anti-A and anti-B is recommended when providing ABO incompatible platelet transfusion. The life-time of reagent cells depends upon the preservative diluents. We aimed to evaluate the IgM titers of anti-A and anti-B testing with magnetized-erythrocyte group antigens (MEGA) and fresh RBCs and study the relationship of ABO antibody titers between both techniques. Altogether, 100 serum samples from group O donors at the National Blood Centre, Thai Red Cross Society, Bangkok, Thailand were included. EDTA blood from three different A and B blood group individuals was prepared as fresh reagent RBCs and MEGA. Each serum sample was tested simultaneously for IgM anti-A and anti-B titers using fresh RBCs and MEGA by standard tube technique. Antibody titers were compared between both techniques. Test for reproducibility and stability of MEGA were performed. The IgM anti-A and anti-B titers using fresh RBCs yielded higher agglutination scores than MEGA (P < 0.001). However, a good correlation was obtained in the agglutination titers (anti-A, r = 0.838 and anti-B, r = 0.877). The mean and standard deviation of anti-A and anti-B titers using MEGA from five sera in triplicate showed no significant difference (P > 0.05). Moreover, the titer test results using MEGA after dilution remained stable up to 8 h. The MEGA can be used as a replacement for fresh RBCs to perform ABO serum grouping. It is simple to use, avoids centrifugation and provides good results in terms of stability and reproducibility.

Detection of MNS hybrid molecules in the Thai population using PCR-SSP technique

We developed a polymerase chain reaction-sequence-specific primer (PCR-SSP) technique to screen for hybrid molecules in the MNS blood group in the Thai population using two sets of newly designed primers specific for four GYP(B-A-B) hybrids, GP.Mur, GP.Hop, GP.Bun and GP.HF, and two GYP(A-B-A) hybrids, GP.Vw and GP.Hut. One thousand and forty-one blood samples were tested with human anti-Mi(a) by conventional tube technique, and 598 samples of these were tested by the PCR-SSP technique. Ninety-four samples (9.03%) were strongly positive with human antisera by conventional tube technique. For PCR-SSP test results, the GP.Hut, GP.Mur, GP.Hop, GP.Bun and GP.HF genotypes were amplified with the first set of primers, whereas GP.Vw genotype was amplified with a second set of primers. The GYP(A-B) hybrids (GP. Hil and GP.JL), GYP(A-B-A) hybrids (GP.Nob, GP.Joh and GP.Dane), GYPA, GYPB and GYPE were not amplified by either set of primers. Results of testing 94 Mi(a+) and 504 Mi(a-) by conventional tube technique and PCR-SSP were concordant. This study shows that analysis by PCR-SSP is simple and convenient; therefore, it can be used as an alternative to conventional tube technique for mass screening for MNS hybrids, especially when specific antisera are not available.

HLA-B27 testing in Thai patients using the PCR-SSP technique

We develop the HLA-B27 test kit using the PCR-SSP technique. Five hundred forty blood samples were tested for HLA-B27 by microlymphocytotoxicity test (LCT) and PCR-SSP. It was found that 127 (23.5%) and 134 (24.8%) of these samples were positive for HLA-B27 by LCT and PCR-SSP, respectively. The sensitivity and specificity of the PCR-SSP were 94.8 and 100%, respectively, when using LCT as the standard method. The PCR-SSP positive predictive value was 100%, negative predictive value was 98.3%, and a concordance rate of 98.7%. This study shows that the PCR-SSP is simple, convenient, and a more cost-effective in-house test kit.

External quality assessment scheme in red blood cell serology: a 5-year experience in Thailand

From 2000 to 2004, 36, 58, 72, 78, and 86 laboratories participated in an external quality assessment scheme (EQAS) organized by the Department of Transfusion Medicine, Faculty of Medicine Siriraj Hospital. Each year the staff was requested to perform ABO grouping, D typing, antibody screening, antibody identification, and DATs on eight blood samples. Each participant received information on the correct test results and a coded summary. Regarding ABO grouping, the error rate ranged from 0.3 to 1.3 percent, mostly due to human errors. Error rates in D typing ranged from 0.7 to 5.7 percent, the most problematic being weak D phenotype interpretation. Although every sample was negative by the DAT, error rates due to false positive test results were determined to be 0.4 to 2.1 percent. Antibody screening errors were also found; however, errors steadily decreased from 4.2 percent in 2000 to 0.3 percent in 2004. Only 69.4 to 87.2 percent of laboratories performed antibody identification; however, correct results increased from 78.4 to 91.0 percent. In conclusion, an EQAS in RBC serology should be used to compare results from different laboratories and to identify those laboratories that need improvement in testing procedures.

Gene frequencies of the HPA-1 to 6 and Gov human platelet antigens in Thai blood donors

Human platelet alloantigens (HPA) are important in neonatal alloimmune thrombocytopenia (NAIT), posttransfusion purpura (PTP), platelet transfusion refractoriness, passive alloimmune thrombocytopenia, and transplantation-associated alloimmune thrombocytopenia. Thus, HPA genotyping is essential in diagnosis and treatment. We analyzed HPA-1 to 6 and Gov alleles, using PCR with sequence specific primers (PCR-SSP) in 500 Thai blood donors who had been HLA class I antigen typed. HPA-4a was present in all samples. HPA-1b, -2b, -5b, and -6b were rare, and HPA-4b was not found. HPA-3a and -3b showed frequencies of 56.0 percent and 44.0 percent, respectively. Gova and Govb showed frequencies of 49.1 percent and 50.9 percent, respectively. The prevalence rates of HPA-1 to 6 gene frequencies (GFs) were consistent with those of other Asian populations rather than those of Caucasians. We also report on the GFs of Gova and Govb, which also are comparable to those of Asian populations. Our results could establish a useful HPA- and HLA-matched plateletpheresis donor file and provide an improvement of platelet alloantibody detection in alloimmune thrombocytopenic patients, and, therefore, a more effective platelet transfusion program.

Analysis of SERF in Thai blood donors

The Cromer blood group system consists of nine high-prevalence and three low-prevalence antigens carried on decay-accelerating factor (DAF). We recently described one of these Cromer highprevalence antigens,SERF, the absence of which was found in a Thai woman. The lack of SERF antigen in this proband was associated with a substitution of nucleotide 647C>T in exon 5 of DAF, which is predicted to be a change of proline to leucine at amino acid position 182 in short consensus repeat (SCR) 3 of DAF. This study reports on PCR-RFLP analysis of the SERF allele with BstNI restriction endonuclease on more than one thousand Thai blood donor samples. One new donor homozygous (647T) and 21 donors heterozygous (647C/T) for the SERF allele were found. Among this cohort of random Thai blood donors, the SERF allele frequency was 1.1 percent. Thus, like other alleles in the Cromer blood group system, SERF is found in a certain ethnic group.

Mutations at the activated protein C cleavage sites Arg336 and Arg562 of factor VIII in Thai patients with venous thrombosis

Venous thrombosis is a multicausal disease, more than one genetic risk factor may cooperate to effect thrombotic risk. Factor V Leiden is found to be an important hereditary risk factor for venous thromboembolism. Analogous to factor V Leiden, a point mutation at amino acid positions Arg336 and Arg562 in factor VIII may predispose patients to thrombosis. Eighty-one Thai patients with venous thrombosis and 100 Thai healthy volunteers have been studied. Neither heterozygous nor homozygous mutations were detected both thrombosis patients or normal volunteers. However, further studies with larger samples of venous thrombosis patients are recommended.

HLA alloimmunization in patients receiving multitransfusions of red blood cells

HLA antibodies were studied in 88 patients with chronic hemolytic anemia who received multitransfusions of red blood cells prepared by conventional (PRC-C), inverted centrifugation (LR-I) and leukocyte filter (LR-F) techniques. Their mean age was 8 years and 4 months with a duration of transfusion of 8 years. The patients were divided into five groups: group 1, receiving PRC-C (n=20); group 2, receiving LR-I (n=33); group 3, receiving LR-F (n=11); group 4, subsequently receiving LR-I and LR-F (n=10); and group 5, receiving PRC-C followed by LR-I and LR-F (n=14). The HLA class I antibodies were found in 30 out of 88 patients (34%). All were against HLA antigens commonly found in the Thai population. The patients receiving PRC-C exhibited HLA antibodies of 65%, which was significantly higher than those of patients receiving LR-I (24%) and LR-F (0%). Consequently, the transfusion reactions of fever, chill, rash and urticaria were also commonly found in patients receiving PRC-C (13.4%), which was significantly higher than patients receiving LR-I (0.4%) and LR-F (0%). The leukocyte filter technique has been shown to be effective in preventing HLA alloimmunization and transfusion reactions but the price is rather high. For the inverted centrifugation technique, only transfusion reactions were effectively prevented and the HLA alloimmunization continued to develop. A more effective and low-cost method for the removal of leukocytes should be investigated for these multitransfusion patients.

A preliminary study of the distribution of blood group systems in Thai blood donors determined by the gel test

Two hundred blood samples obtained from volunteer blood donors at the Blood Bank, Army Institute of Pathology were studied for red cell groupings in the ABO, Rh, MNSs, Duffy, Lewis. P. Kell, Lutheran and Kidd Systems. Each sample was tested by the gel test using five cards; the ABO-Rh card, Diaclon Rh sub groups + K card, Antigen profile I card (P, Le(a), Le(b), Lu(a), Lu(b)), Antigen profile II card (k, Kp(a), Kp(b), Jk(a), Jk(b)) and Antigen profile III card (M, N, S, s, Fy(a), Fy(b)). For the ABO System, group O is the most common (40.5%) followed by group B (30.5%), group A (20.5%) and group AB (8.5%). The most common Rh gene complex was CCDee (51.5%), which was similar to other studies. The incidence of MMss and MNss gene complexes were the most common in the MNSs System. Fy(a) is very common as in other Asians. In the Lewis System, the incidence of Le (a-b-) was 23.5%, which is consistent with other findings in the Thai population. Sixty (30%) were positive with anti-P1. For the Kell System, only kk and Kp(b) positive types were observed in this study, as well as Lu (a-b+) in the Lutheran System. Jk (a-b-) was not found, which is considered a rare phenotype among Thai people. This study reveals the blood group distribution in 200 Thai volunteers using the gel test. Because of its simplicity and efficacy, this test is practical in population studies. Moreover, it is useful for mass screening and application in emergency situations.

HLA class II alleles in Japanese patients with non-Hodgkin's lymphoma

The distribution of HLA-DRB1 alleles and DQB1 alleles in 30 Japanese patients with non-Hodgkin's lymphoma (NHL) was analyzed using polymerase chain reaction with the sequence-specific primer (PCR-SSP) method, and the association between the disease and the presence of certain HLA class II alleles was investigated. The frequencies of HLA-DRB1*0803, DRB1*0802 and DRB1*1502 were increased while those of DRB1*1501 and DRB1*0405 were decreased. On the other hand, the incidence of HLA-DQB1 alleles was similar to that in the normal population. However, none of these HLA class II alleles showed significant positive or negative associations with NHL. In addition, when allele frequencies of NHL Japanese patients were compared to Thai patients, only DRB1*0803 was significantly increased in Japanese patients. These results indicate that DRB1*0803 may not contribute to NHL susceptibility in the Japanese population. However, further studies with larger numbers of NHL Japanese patients are needed to confirm our preliminary findings.

Detection of factor V Leiden in Thai patients with venous thrombosis

The molecular defect underlying activated protein C resistance (APC-R) is caused by a G to A point mutation in the codon for arginine 506 in the factor V gene (factor V Leiden) which is a major risk factor for venous thrombosis, especially in Caucasian populations. This study is an analysis of the Thai population to determine the prevalence of the factor V Leiden mutation. Twenty-seven patients with apparent venous thrombosis were divided into two groups according to APC-R test. Thirteen patients were diagnosed as positive for n-APC-SR, ratio < 0.8 and fourteen patients were diagnosed as negative for n-APC-SR, ratio > 0.8. Two of thirteen APC-R positive patients and one of fourteen APC-R negative patients were found to have the heterozygous allele for the factor V Leiden mutation but the homozygous allele was not detected in these groups of patients. Neither the heterozygous nor homozygous Leiden mutation was detected in 200 healthy volunteer blood donors. In conclusion, our findings indicate that factor V Leiden mutation is related to venous thrombosis in Thai people. Moreover, a further study of other mutations at the activated protein C cleavage sites of factor V and factor VIII is recommended.

Comparison of the RPHA and EIA techniques for the detection of HBs antigen among pregnant Thai women

Five hundred serum samples obtained from pregnant women attending an antenatal clinic in Bangkok were tested for HBsAg by reverse passive hemagglutination assay (RPHA) and enzyme immunoassay (EIA). It was found that 21 (4.2%) and 28 (5.6%) of the sera were positive by RPHA and EIA, respectively. The sensitivity and specificity of the RPHA were 75% and 100%, respectively, when using EIA as the standard method. The RPHA positive predictive value was 100% and the negative predictive value was 98.5%. Accuracy was 98.6%. This study showed that the RPHA was simple and required inexpensive equipment, making it suitable for mass screening. However, the possibility of false negative readings due to low levels of HBsAg should be kept in mind, especially in the blood transfusion practice.

HLA class II polymorphism in Thai patients with non-Hodgkin's lymphoma

The distribution of HLA-DRB1 alleles and DQB1 alleles in 100 Thai patients with non-Hodgkin's lymphoma (NHL) was analysed using the polymerase chain reaction with sequence-specific primer (PCR-SSP) method, and the association between the disease and the presence of certain HLA class II alleles was investigated. The frequencies of HLA-DRB1*1502 and DRB1*09012 were increased while those of DRB1*0404, DRB1*0803 and DRB1*1106 were decreased. On the other hand, the incidence of HLA-DQB1 alleles was similar to that in the normal population. Interestingly, only HLA-DRB1*1502 showed a significant positive association with NHL, especially in patients < or / = 45 years and in male patients. It is concluded that the DRB1*1502 allele may contribute to NHL susceptibility in the Thai population. However, further studies on the functional roles of the HLA class II alleles are necessary to elucidate NHL susceptibility.

Comparative analysis of serological and molecular results for HLA-DR typing in 120 Thai subjects

In this study, serological HLA-DR typing results were compared to typing results obtained with sequence-specific primers in the polymerase chain reaction (PCR-SSP). HLA-DR typing was performed on 120 random Thai individuals. Differences in HLA-DR typing results were found in 18 out of 120, which were due to cross reactive antibodies and the lack of potent antisera to define proper HLA-DR splits by serology. Furthermore, PCR-SSP is fast and easy to perform as HLA-DR typing results can be obtained within 2 hours. From the results of this study it can be concluded that PCR-SSP is a reliable and promising technique for HLA-DR typing which can replace the serological technique in routine clinical practice.

Effects of heparin on polymerase chain reaction for blood white cells

Polymerase chain reaction (PCR) has been used with increasing frequency to diagnose infectious and genetic diseases. In this study, the effects of heparin on PCR were investigated, because heparinized blood may sometimes be used in PCR studies. HLA-DQA1 gene amplification was used as a model. PCR was clearly interfered with when heparinized blood was used as a source of template DNA, and the degree of interference was affected by the following three factors; (1) type of Taq DNA polymerase; (2) leukocyte count in blood; and (3) concentration of heparin contained. When additional tests were conducted with additions of definite heparin concentrations to a PCR reaction mixture, specimens with large amounts of DNA tended to exhibit less interference by heparin. The addition of > or = 0.1 to 0.0016 U of heparin per reaction mixture (50 microl) suppressed DNA amplification in a dose-dependent fashion. We therefore concluded that much care should be taken when heparinized blood is used as a PCR material.

HLA class I antibodies in thalassemic patients

This study was undertaken to demonstrate the prevalence of HLA class I antibodies among 62 polytransfused patients. The diagnosis included beta-thalassemia major, beta-thalassemia/Hb E disease and severe Hb H disease. Their ages ranged from 1 year to 23 years with the mean age of 10.7 years. The number of packed red cell transfusions ranged from 3 to 235 with the mean of 60 episodes per patient. The standard microlymphocytotoxicity test was performed using 50 panels of lymphocytes which specifically identified the majority of HLA class I antibodies. 31/62 cases (50%) were positive for HLA class I antibodies. The detection of single or multiple antibodies depended upon the number of blood transfusions and the patients' ages. These antibodies were induced by the leukocytes present in the transfused packed red cells. Therefore, leukocyte-reduced packed red cells prepared by either additional inverted centrifrugation or leukocyte filter is suggested for the routine blood bank service.

Detection of thalassemia genes using smeared blood film or leukocytes adhering to polysthylene fibers

Presently genetic analyses for thalassemia types require relatively large amounts of heparinized blood (5 to 10 ml), and transport as well as degeneration of these sample is a problem in the developing world. We have developed a new method to simplify this procedure and obtain DNAs from small specimens. As experimental materials, thinly smeared blood on a glass slide or blood filtered with and adhered on polysthylene telephtalate (PST) fibers were used. These materials could be safely stored without interfering with DNA extraction for up to 3 months. The slide materials were digested with proteinase K, and DNA was extracted with Tris-EDTA-phenol:chloroform and precipitated with absolute ethanol. The PST specimens were washed with physiologic saline and treated in the same manner as described above. Products were easily amplified by PCR and digested with restriction endonucleases for beta thalassemia typing as well as for HLA-DQA1 gene typing. Results obtained by this method correlated well with previously reported incidences for thalassemia and HLA-DQA1 types in Thailand. This method can be used in the routine laboratory because it allows for stable and biosafe genetic analyses.

A preliminary study of HLA class II alleles in Thai patients with non Hodgkin's lymphoma

The HLA class II alleles were analyzed by the PCR-SSP technique in the DNA samples obtained from 27 Thai patients with non Hodgkin's lymphoma (NHL). It was found that (1) the incidence of HLA-DRB1*15 and HLA-DRB1*09 was slightly decreased (P > 0.05). On the other hand, the incidence of HLA-DQB1 alleles was the same as control. However, further study is suggested in order to conclude the close relationship between the presence of certain HLA class II alleles and susceptibility to NHL in Thai patients.

A comparative study of three techniques for eluting red cell antibodies

Sixty-seven eluates obtained from the heat, ether and acid elution techniques were tested with the specific red blood cells (RBCs) and were compared according to their reactivities using the indirect antiglobulin test (IAT). It was found that the ether elution technique was superior in eluting Rh antibodies except for anti-e while the acid elution technique was superior in eluting Miltenberger (Mi(a)) antibodies (P < 0.05). The heat elution technique gave the lowest reactivity among the three techniques. In conclusion, the reactivities of the eluates obtained from the acid elution technique were overall comparable to those from the ether elution technique. The acid elution technique is practical for routine use in most blood banks because it is less time consuming and reduces the risk of exposing hazardous chemicals.

The benefit of the direct antiglobulin test using gel technique in ABO hemolytic disease of the newborn

The direct antiglobulin test (DAT) using the gel technique was included in the investigation of infants with hyperbilirubinemia in the first week of life. Twelve cases were preterm and 48 cases were full term infants. The patients were divided into 2 groups: the study group comprised 22 cases of blood group A or B infants born to blood group O mothers; the control group comprised 38 cases of ABO blood groups compatible with those of their mothers. The mean +/- SD (39 +/- 26 hours) of the age at the onset of hyperbilirubinemia induced by ABO hemolytic disease of the newborn (HDN) was significantly earlier than that due to other causes. The positive rate of DAT in the ABO incompatible group was similar by both the conventional technique and the gel technique, 54.5% and 50% respectively. However, the scores by the gel technique were higher than those of the conventional technique. The gel technique is simple, reliable, involves less technical error and requires a small amount of blood sample. The grading system is clear-cut, especially grade 1 + or weak positive as compared to the conventional technique which requires examination under a microscope. Therefore, the DAT using the gel technique is beneficial to the diagnosis of ABO HDN. It should be included in the investigation of infants with hyperbilirubinemia especially in case of suspected ABO HDN.

Comparison between the conventional tube technique and the gel technique in direct antiglobulin tests

OBJECTIVES

The direct antiglobulin test (DAT) is a diagnostic procedure demonstrating in-vivo antibody or complement coating on red cells. The gel technique (GT) for this test is sensitive and easier to do than the conventional tube technique (CTT).

METHODS

We tested 52 newborns with hyperbilirubinemia and 6 children and 17 adults with autoimmune hemolytic anemia (AIHA) using the (DAT) in the form of the conventional tube technique (CTT) and the gel technique (GT) simultaneously. The gradings of the agglutination reactions of both techniques were scored as 12, 10, 8, 5, 3, 0 for 4+, 3+, 2+, 1+ and w+ and negative, respectively.

RESULTS

The GT yielded higher scores than the CTT (p < 0.01). The overall sensitivity and specificity of the GT were 93.5 and 88.6%, respectively. The specificity of the DAT-positive results in newborns was determined by IgG only, while in AIHA, it was determined by IgG and/or C3d and, in only one sample, by IgM.

CONCLUSION

The GT is equal to or better than the CTT. Since the GT is simple, the exposure of blood bank personnel to the blood sample is low. We highly recommend the GT, especially in areas where HIV infection is prevalent.