Application of a simplified PCR-SSP method to detect A4GALT*01 and A4GALT*02 typing among Thai blood donors

OBJECTIVES

An intronic A4GALT single nucleotide variant, rs5751348:G>T, P2 or A4GALT*02 allele has a lower level of the enzyme-encoding A4GALT transcripts than the P1 individuals. Here, we first develop and validate a simple inhouse PCR-SSP method to detect A4GALT*01 and A4GALT*02 alleles, and second, apply this method to compare the allele frequencies between Thai and other populations.

MATERIAL AND METHODS

The conventional test tube technique was used to detect the P1 antigen in 222 blood samples from Thai blood donors at Thammasat University Hospital. A PCR-SSP method was optimized and validated for reproducibility and specificity to identify these alleles and was subsequently tested on 1,840 DNA samples of unknown phenotypes obtained from central, northern and southern Thais. In addition, allele frequencies of central Thais were compared with those of other populations.

RESULTS

In the tested cohort (n = 222), P1 and P2 phenotypes were typed in 26.13 and 73.87% of donors, respectively. The developed PCR-SSP was successfully optimized, and the outcomes were consistent with those of serological phenotyping and DNA sequencing results, demonstrating its validity for predicting P1/P2 phenotype. For central, northern and southern Thais, the A4GALT*01 frequency was 0.1579 (430/2,724), 0.1183 (71/600), and 0.2575 (206/800), whereas the A4GALT*02 frequency was 0.8421 (2,294/2,724), 0.8817 (529/600), and 0.7425 (594/800), respectively. Their observed frequencies among central Thais significantly differed from those in other populations (p < 0.05).

CONCLUSION

Our study has successfully developed a simple, precise, and reliable method to genotype A4GALT*01 and A4GALT*02 using inhouse developed PCR-SSP for predicting P1/P2 status.

Ultrarapid and high-resolution HLA class I typing using transposase-based nanopore sequencing applied in pharmacogenetic testing

Nanopore sequencing has been examined as a method for rapid and high-resolution human leukocyte antigen (HLA) typing in recent years. We aimed to apply ultrarapid nanopore-based HLA typing for HLA class I alleles associated with drug hypersensitivity, including HLA-A*31:01, HLA-B*15:02, and HLA-C*08:01. Most studies have used the Oxford Nanopore Ligation Sequencing kit for HLA typing, which requires several enzymatic reactions and remains relatively expensive, even when the samples are multiplexed. Here, we used the Oxford Nanopore Rapid Barcoding kit, which is transposase-based, with library preparation taking less than 1 h of hands-on time and requiring minimal reagents. Twenty DNA samples were genotyped for HLA-A, -B, and -C; 11 samples were from individuals of different ethnicity and nine were from Thai individuals. Two primer sets, a commercial set and a published set, were used to amplify the HLA-A, -B, and -C genes. HLA-typing tools that used different algorithms were applied and compared. We found that without using several third-party reagents, the transposase-based method reduced the hands-on time from approximately 9 h to 4 h, making this a viable approach for obtaining same-day results from 2 to 24 samples. However, an imbalance in the PCR amplification of different haplotypes could affect the accuracy of typing results. This work demonstrates the ability of transposase-based sequencing to report 3-field HLA alleles and its potential for race- and population-independent testing at considerably decreased time and cost.

Genotyping Approach to Predict Coa and Cob Antigens in Thai Blood Donor Populations

Purpose

Co^a and Co^b antigens of the Colton (CO) blood group system are implicated in acute and delayed hemolytic transfusion reactions (HTRs). Owing to the inadequate supply of specific antiserum, data on CO phenotypes remain limited. This study aimed to develop genotyping methods to predict Co^a and Co^b antigens and to estimate transfusion-induced alloimmunization risks in three Thai blood donor populations.

Materials and Methods

The study included 2451 blood samples from unrelated healthy Thai blood donors obtained from central, northern, and southern Thailand. DNA sequencing was used to determine the CO*A and CO*B alleles. In-house PCR with sequence-specific primers (PCR-SSP) and high-resolution melting curve (HRM) assays were performed and genotyping results were compared using DNA sequencing. CO*A and CO*B allele frequencies among Thais were determined using PCR-SSP and their frequencies were compared with other populations. The risks of Co^a and Co^b transfusion-induced alloimmunization among Thai donor populations were calculated.

Results

The validated genotyping results by PCR-SSP and HRM assays agreed with DNA sequencing. The CO*A/CO*A was the most common (100.0, 100.0, and 99.3%), followed by CO*A/CO*B (0.0, 0.0, and 0.7%) among central, northern and southern Thais. Homozygous CO*B/CO*B was not found. The CO*A and CO*B allele frequencies among central Thais significantly differed compared among southern Thais (p < 0.01) but not among northern Thais. Those allele frequencies among Thais were similar to those of Taiwanese, Chinese and Malay-Malaysian populations but not to South Asian, Southeast Asian, Korean, Japanese, Filipino, French Basque, and Maltese populations (p < 0.01). A higher risk of anti-Co^b production rather than anti-Co^a production was particularly noted in the southern Thai population.

Conclusion

This study constitutes the first to determine CO*A and CO*B genotypes using PCR-SSP and HRM assays among Thais and this finding would be beneficial in predicting alloimmunization risk and providing safe transfusions among Thais.

Two novel alleles on Fucosyltransferase 2 from northern Thai para-Bombay family and computational prediction on mutation effect

BACKGROUND

Major characteristics of the para-Bombay phenotype are the absence of ABH antigens on red blood cells due to fucosyltransferase 1 (FUT1) gene mutation and the presence of these antigens in body secretions due to the active fucosyltransferase 2 (FUT2) gene. An ABO blood group discrepancy can be identified via serological testing, and additional tests can be performed for confirmation. This study aimed to resolve the ABO discrepancy and report two novel alleles on the FUT2 gene in northern Thai para-Bombay families.

STUDY DESIGN AND METHODS

Twelve blood samples were collected from five suspected para-Bombay donors and their families. Nucleotide sequences of ABO, FUT1, and FUT2 were analyzed by polymerase chain reaction-sequence-based typing. Bioinformatics tools were used to predict the effect of suspected novel FUT2 alleles.

RESULTS

All samples exhibited normal ABO alleles, concordant with serological test results. FUT1 exhibited three known variants (c.328G>A, c.424C>T, and c.658C>T). Although FUT2 exhibited two known variants (c.357C>T and c.385A>T), two novel alleles were observed. One allele consisted of c.98A>G, c.101T>G, and c.357C>T with predicted normal transferase activity, whereas the other consisted of c.357C>T and c.617T>C with predicted abnormal enzyme activity.

DISCUSSION

Two novel alleles in FUT2 were reported among the affected para-Bombay individuals of northern Thai families. The c.617T>C variant caused an amino acid change from valine to alanine at position 206, predicted to be an inactive FUT2 enzyme. Inheritance of this variant with the recessive FUT1 allele may lead to inheritance of the rare Bombay blood group in the progeny.

Development of DO*A and DO*B Allele Detections to Predict Transfusion-Induced Alloimmunization Risks in Thai Populations

BACKGROUND

Two antithetical antigens, Doa and Dob of the Dombrock (DO) blood group system are implicated in acute to delayed hemolytic transfusion reactions among patients with anti-Doa or anti-Dob. Given the unavailability of specific antiserum, a polymerase chain reaction with sequence-specific primer (PCR-SSP) was developed to identify DO*A and DO*B alleles. This study aimed to determine DO*A and DO*B allele frequencies and to predict transfusion-induced alloimmunization risks in three Thai blood donor populations.

METHODS

DNA samples obtained from 1,300, 300, and 400 blood donors from central, northern, and southern Thailand, respectively, were genotyped for the DO*A and DO*B allele detections using developed PCR-SSP. The results were confirmed by DNA sequencing.

RESULTS

The validated genotyping results by PCR-SSP were in concordance with DNA sequencing. The DO*B/ DO*B was the most common genotype (77.0, 76.0, and 71.0%), followed by DO*A/DO*B (21.0, 22.7, and 25.2%) and DO*A/DO*A (2.0, 1.3, and 3.8%) among central, northern and southern Thais, respectively. The alleles found among central Thais showed significant differences from those found among southern Thais but not from those of northern Thais. The risk of anti-Doa production was higher than anti-Dob production among Thais. Concerning regional groups, the risk of Doa alloimmunization among southern Thais (0.2059) was higher than those among central (0.1771) and northern Thais (0.1824).

CONCLUSIONS

This was the first study to distinguish DO*A and DO*B genotypes in Thai populations using in-house PCR-SSP. This would be useful to predict alloimmunization risks that might result from transfusion-induced reactions of undetermined red cell antigens among blood donors and in reagent red cells.

Iron-Quercetin Complex Preconditioning of Human Peripheral Blood Mononuclear Cells Accelerates Angiogenic and Fibroblast Migration: Implications for Wound Healing

Cell-based therapy is a highly promising treatment paradigm in ischemic disease due to its ability to repair tissue when implanted into a damaged site. These therapeutic effects involve a strong paracrine component resulting from the high levels of bioactive molecules secreted in response to the local microenvironment. Therefore, the secreted therapeutic can be modulated by preconditioning the cells during in vitro culturing. Herein, we investigated the potential use of magnetic resonance imaging (MRI) probes, the "iron-quercetin complex" or IronQ, for preconditioning peripheral blood mononuclear cells (PBMCs) to expand proangiogenic cells and enhance their secreted therapeutic factors. PBMCs obtained from healthy donor blood were cultured in the presence of the iron-quercetin complex. Differentiated preconditioning PBMCs were characterized by immunostaining. An enzyme-linked immunosorbent assay was carried out to describe the secreted cytokines. In vitro migration and tubular formation using human umbilical vein endothelial cells (HUVECs) were completed to investigate the proangiogenic efficacy. IronQ significantly increased mononuclear progenitor cell proliferation and differentiation into spindle-shape-like cells, expressing both hematopoietic and stromal cell markers. The expansion increased the number of colony-forming units (CFU-Hill). The conditioned medium obtained from IronQ-treated PBMCs contained high levels of interleukin 8 (IL-8), IL-10, urokinase-type-plasminogen-activator (uPA), matrix metalloproteinases-9 (MMP-9), and tumor necrosis factor-alpha (TNF-α), as well as augmented migration and capillary network formation of HUVECs and fibroblast cells, in vitro. Our study demonstrated that the IronQ-preconditioning PBMC protocol could enhance the angiogenic and reparative potential of non-mobilized PBMCs. This protocol might be used as an adjunctive strategy to improve the efficacy of cell therapy when using PBMCs for ischemic diseases and chronic wounds. However, in vivo assessment is required for further validation.

The effects of text messaging for promoting the retention of the first-time blood donors, a randomized controlled study (TEXT study)

BACKGROUND

Donor recruiting remains a challenging process to obtain sufficient blood product supply worldwide. This was a randomized controlled trial aimed to evaluate the efficacy of text messaging for promoting the retention of first-time blood donors.

STUDY DESIGN AND METHODS

Participants enrolled were 18 years of age or older who were first-time blood donors and able to understand text messages. Participants were randomized in a 1:1 ratio (text group vs control group). Only participants who were allocated in the "text group" received a text message once their blood product was dispatched from the transfusion service. The content of the text message was "We would like to inform you that your blood has been used for patients on the date (DD/MM/YY)." The primary outcome of the study was the rate of returning at 9 months after the first donation.

RESULTS

In an intention-to-treat analysis, 1270 participants were allocated to the text group and 1270 participants to the control group. The primary outcome occurred in 199 in the text group (22.4 per 100 donor-years) and 152 in the control group (16.9 per 100 donor-years). The incidence rate ratio was 1.31 (95% confidence interval, 1.06-1.63; P = .005). The number needed to treat was 22. The median time to return for blood donation was 112 days (interquartile range [IQR], 98-146) in the text group and 113 days (IQR, 97-144) in the control group.

CONCLUSION

Among first-time blood donors, text messaging after blood product being dispatched is an effective and simple intervention to increase the retention rate for subsequent donations.

HLA-DRB1*04:05 and HLA-DQB1*04:01: Alleles Potentially Associated with Vogt-Koyanagi-Harada in Northern Thai Patients

PURPOSE

To determine the frequency and association of alleles at human leukocyte antigen (HLA)-DRB1 and HLA-DQB1 loci in VKH disease patients from Northern Thailand.

METHODS

A case-control study was conducted with three subject groups: 23 VKH patients, 20 patients with other uveitis entities, and 40 healthy blood donors. HLA-DRB1 and HLA-DQB1 loci were analyzed and the frequency of HLA-DRB1 and HLA-DQB1 alleles was calculated by direct counting. The measure of association was calculated by odds ratio (OR) and 95% confidence interval.

RESULTS

In VKH patients, the most prevalent allele was HLA-DRB1*04:05, found in 35% of patients and with the highest OR (42.13). HLA-DQB1*04:01 was the next most prevalent, found in 23.91% of VKH patients. HLA-DQB1*05:02 was also detected in 23.91% of patients; however, a higher prevalence was observed in non-VKH and healthy controls (30% and 35%, respectively).

CONCLUSION

HLA-DRB1*04:05 and HLA-DQB1*04:01 could be potential genetic markers for VKH.

Impact of using genotyping to predict SERF negative phenotype in Thai blood donor populations

Background

SERF(+) is a high prevalence antigen in the Cromer blood group system that is encoded by a CROM*01.12 allele. The SERF(-) on red cells is caused by a single nucleotide variation, c.647C>T, in exon 5 of the Decay-accelerating factor,DAF gene. Alloanti-SERF was found in a pregnant Thai woman, and a SERF(-) individual was found among Thai blood donors. Since anti-SERF is commercially unavailable, this study aimed to develop appropriate genotyping methods for CROM*01.12 and CROM*01.-12 alleles and predict the SERF(-) phenotype in Thai blood donors.

Methods

DNA samples obtained from 1,580 central, 300 northern, and 427 southern Thai blood donors were genotyped for CROM*01.12 and CROM*01.-12 allele detection using in-house PCR with sequence-specific primer (PCR-SSP) confirmed by DNA sequencing.

Results

Validity of the PCR-SSP genotyping results agreed with DNA sequencing; CROM*01.12/CROM*01.12 was the most common (98.42%, 98.00%, and 98.59%), followed by CROM*01.12/CROM*01.-12 (1.58%, 2.00%, and 1.41%) among central, northern, and southern Thais, respectively. CROM*01.-12/CROM*01.-12 was not detected in all three populations. The alleles found in central Thais did not significantly differ from those found in northern and southern Thais.

Conclusion

This study is the first to distinguish the predicted SERF phenotypes from genotyping results obtained using in-house PCR-SSP, confirming that the CROM*01.-12 allele frequency ranged from 0.007 to 0.010 in three Thai populations. This helps identify the SERF(-) phenotype among donors and patients, ultimately preventing adverse transfusion reactions.

Establishment of KEL*01 and KEL*02 Genotyping to Recruit Uncommon, Kell-positive, Reagent Red Cells Among Thai Blood Donors

BACKGROUND

The reagent red blood cells used to screen and identify antibodies have to include K+ cells in all batch productions. The data of K/k phenotypes among differing Thai blood donor populations remains unknown; hence, mass screening for uncommon K+ donors by serological test has some limitations. Implementing K/k genotyping may be useful to predict uncommon K+ donors to overcome this challenge. This study aimed to establish an in-house K/k genotyping technique and to report KEL*01 and KEL*02 allele frequencies among three Thai blood donor populations to increase the selection of K+ donors in rare blood group databases.

METHODS

A total of 2,239 DNA samples obtained from 1,512 central, 427 southern, and 300 northern Thai blood donors were included. The KEL*01 and KEL*02 genotyping using PCR with sequence-specific primers (PCR-SSP) was developed and validated. All samples were genotyped using developed PCR-SSP. Moreover, the possibility of finding group O and predicted K+ phenotypes among Thai blood donor populations was calculated.

RESULTS

The DNA controls were validated using two sets of primer combinations and the results of KEL*01 and KEL*02 genotyping were in agreement. The KEL*01 allele frequencies were 0.0007, 0.0047, and 0.0000, and KEL*02 allele frequencies were 0.9993, 0.9953, and 1.0000 among central, southern, and northern Thai donors, respectively. In addition, mass screening among 3,795 and 566 donors in central and southern Thai populations was required to find at least one group O and predicted K+ phenotypes.

CONCLUSIONS

The in-house PCR-SSP for KEL*01 and KEL*02 genotyping provided reproducible and accurate results with cost effectiveness. Our results confirmed the low KEL*01 allele frequencies among Thais. PCR-SSP could be used as an alternative technique to simply increase the number of uncommon predicted K+ phenotypes for reagent red blood cell recruitments.

Inactivation of Zika virus in plasma and derivatives by four different methods

Zika virus (ZIKV) is an emerging arbovirus with increasing prevalence in recent years. To reduce the risk of ZIKV transmission by transfusion, some mitigation strategies were recommended based on pathogen reduction technologies for blood products. In this study, we aimed to study the efficacy of several common pathogen reduction methods in the inactivation of ZIKV. The fresh frozen plasma and derivatives were spiked with a high titer of ZIKV or Sindbis virus (SINV). Viral titers and ZIKV RNA were measured before and after the inactivation treatment by methylene blue (MB), solvent/detergent (S/D), pasteurization, and low pH. The mean ZIKV infectivity titers in plasma and derivatives were 7.08 ± 0.14, 5.17 ± 0.14, 7.08 ± 0.14, and 5.80 ± 0.14 log₁₀ TCID₅₀ /mL, respectively before MB, S/D, pasteurization, and low pH inactivation. We found no detectable ZIKV RNA after five successive passages of inoculation on host cells, indicating there is no infectivity after inactivation. Similar inactivation results were observed for SINV. In conclusion, we achieved robust ZIKV inactivation through the four inactivation procedures in several blood products. These findings suggest that the pathogen reduction technologies commonly applied in plasma and derivatives have the capacity to mitigate the risk of ZIKV transmission by transfusion.

Mixed-field agglutination observed in column agglutination testing is not always associated with the A3 subgroup

Mixed-field agglutination (MFA) can be observed in forward typing of samples from A3 individuals with serologic ABO typing methods. The results of column agglutination testing (CAT) and tube agglutination testing using different antibody clones can be discordant. In this report, we reveal our experience using polymerase chain reaction-sequence-based typing (PCR-SBT) of ABO exon 7 to clarify serologic method discordance of A subgroup blood typing in Northern Thai donors. A total of 21 group A blood donors with either MFA or weak agglutination on routine ABO CAT were recalled. CAT was repeated with human and monoclonal anti-A, and tube agglutination testing with monoclonal anti-A and PCR-SBT of ABO exon 7 was performed. A total of 13 of the 21 donors returned, and ABO CAT with human anti-A was repeated. Eleven samples showed MFA suspected to be the A3 subgroup, and two samples showed 2+ strength suspected to be the Aweak subgroup. When tube agglutination testing using monoclonal antibody was performed, MFA was not observed in 9 of 11 samples with previously observed MFA from routine CAT, which were then interpreted as A2. From PCR-SBT performed in only exon 7 of the ABO gene, 7 of 13 sample results were consistent with ABO*A2 or ABO*AW alleles. Two samples suspected to be A2 or A3 had an ABO*AW allele. In two samples suspected to be Aweak, no mutation was detected in ABO exon 7, suggesting genetic variation elsewhere in the gene. Although other coding exons were not examined, in the alleles that could be assigned, ABO*A3 alleles were found less frequently than would be predicted from the serologic findings. These findings suggest that when MFA in routine CAT is observed, an A3 subgroup cannot be presumed. Caution should be exercised when MFA is noted in routine CAT.

Red Cell Genotyping by Multiplex PCR Identifies Antigen-Matched Blood Units for Transfusion-Dependent Thai Patients

BACKGROUND

Antigen-negative red cell transfusion is required for transfusion-dependent patients. We developed multiplex PCR for red cell genotyping and calculated the possibility of finding compatible predicted phenotypes in Thai blood donor populations according to red cell alloantibodies found among Thai patients.

METHODS

600 DNA samples obtained from unrelated healthy central and northern Thai blood donors were tested with the newly developed multiplex PCR for FY*A, FY*B, JK*A, JK*B, RHCE*e, RHCE*E, DI*A and GYP*Hut, GYP*Mur, GYP*Hop, GYP*Bun, and GYP*HF allele detections. Additionally, the possibility of finding compatible predicted phenotypes in two Thai blood donor populations was calculated to estimate the minimal number of tests needed to provide compatible blood.

RESULTS

The validity of multiplex PCR using known DNA controls and the phenotyping and genotyping results obtained by serological and PCR-SSP techniques were in agreement. The possibility of finding at least one compatible blood unit for patients with multiple antibodies was comparable in Thai populations.

CONCLUSIONS

The multiplex PCR for red cell genotyping simultaneously interprets 7 alleles and 1 hybrid GP group. Similar strategies can be applied in other populations depending on alloantibody frequencies in transfusion-dependent patients, especially in a country with limited resources.

Frequencies of human neutrophil antigen-4 and human neutrophil antigen-5 among Thai blood donors

Context:

Antibodies against human neutrophil antigens (HNAs) are implicated in immune-mediated neutropenia, transfusion-related acute lung injury and febrile transfusion reactions.

Aims:

This study aimed to determine HNA gene frequencies of the HNA-4 and HNA-5 systems among Thai populations and compare these frequencies with those previously reported for other populations.

Materials and Methods:

800 DNA samples obtained from 500 unrelated healthy blood donors from Bangkok and 300 samples from Chiang Mai, Thailand were included. Samples were typed for each HNA allele including HNA-4a, HNA-4b, HNA-5a, and HNA-5b using an in-house polymerase chain reaction with sequence-specific primer technique.

Results:

The frequencies of HNA-4a and HNA-4b alleles in central Thais were 0.975 and 0.025, respectively and for Northern Thais, their frequencies were 0.965 and 0.035, respectively. For HNA-5a and HNA-5b alleles, their frequencies were 0.771 and 0.229; 0.748, and 0.252 in central and Northern Thais, respectively. The frequencies of HNA-4 and HNA-5 systems in central Thais are closely related to those in Northern Thais (P > 0.05). However, their frequencies were different from other populations (P < 0.001), except HNA-5a and HNA-5b gene frequencies in Thais were similar to Caucasians (P > 0.05).

Conclusion:

This study could contribute to predict the risk of alloimmunization to HNA-4 and HNA-5 systems, especially in feto-maternal incompatibility in Thais.

Risk estimation of HNA-3 incompatibility and alloimmunization in Thai populations

Severe transfusion-related acute lung injury (TRALI) is often due to antibodies in blood components directed against human neutrophil antigen (HNA)-3a. This study aimed to report the genotype frequencies of the HNA-3 system and to estimate the potential risk of HNA-3 incompatibility and alloimmunization in two Thai populations. Eight hundred DNA samples obtained from 500 unrelated healthy blood donors at the National Blood Centre, Thai Red Cross Society, Bangkok and 300 samples from the Blood Bank, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand were included. HNA-3 genotyping was performed using an in-house polymerase chain reaction with sequence-specific primer (PCR-SSP) technique. The observed frequencies of the HNA-3a/3a, HNA-3a/3b, and HNA-3b/3b genotypes were 0.528, 0.380, and 0.092 in central Thais and 0.600, 0.350, and 0.050 in northern Thais, respectively. The frequencies were used to estimate HNA-3 incompatibility and risk of HNA-3a alloimmunization. The HNA-3 incompatibility in central Thais (33.28%) was higher than northern Thais (28.75%), corresponding to a significantly higher probability of HNA-3a alloimmunization (P<0.05) similar to Japanese and Chinese populations. This study showed the high risk of HNA-3 incompatibility and alloimmunization, especially in central Thai blood donors. A molecular-based identification of the HNA-3 genotype of female donors is suggested to reduce the risk of TRALI following plasma and whole blood allogeneic transfusion.

Frequency of FCGR3B alleles in Thai blood donors

Background

Human neutrophil antigens (HNAs) are involved in autoimmune and alloimmune neutropenia and transfusion-related acute lung injury. The HNA-1 system is important in immunogenetics, and allele frequencies have been described in different populations. This study investigated the frequency of FCGR3B alleles encoding HNA-1a, HNA-1b, and HNA-1c among Thai blood donors and compared these frequencies with those previously reported for other populations.

Methods

Eight hundred DNA samples obtained from unrelated healthy blood donors at the National Blood Centre, Thai Red Cross Society, Bangkok, and the Blood Bank, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand, were included. Samples were simultaneously typed for each FCGR3B allele using an in-house polymerase chain reaction with sequence-specific primer (PCR-SSP) technique.

Results

The frequencies of FCGR3B*1, FCGR3B*2, and FCGR3B*3 alleles in central Thai blood donors were 0.548, 0.452, and 0.004, respectively; only FCGR3B*1 and FCGR3B*2 alleles were found in northern Thai blood donors (0.68 and 0.32, respectively). Compared with other Asian populations, central Thais had higher frequencies of the FCGR3B*2 allele (P<0.001), while the frequencies of the FCGR3B*1 and FCGR3B*2 alleles in northern Thais were similar to those previously reported in Taiwanese and Japanese populations. In contrast, the frequencies of the FCGR3B*1 and FCGR3B*2 alleles in the northern Thai population were statistically different from those observed in central Thai, Korean, German, and Turkish populations.

Conclusions

FCGR3B allele frequencies were significantly different between central and northern Thai blood donors. Our in-house PCR-SSP method is a simple, cost-effective, and convenient method for FCGR3B allele detection.

Assessment of a self-deferral form for screening blood donors, Chiang Mai University Hospital, Thailand

A self-deferral form has been used to screen Chiang Mai University Hospital blood donors and was improved in 2005. It has never been evaluated. The study aimed to assess the self-deferral form procedures in detecting infected donors. Sera from 5,083 donors, who passed the self-deferral screening form, were tested with the routine immuno-assays (serology) for HIV 1 and 2 antibodies, P24 antigen, HCV antibodies, HBV surface antigen, and syphilis. Antibody negative sera were also tested individually with the the Procleix Ultrio Assay for HIV-1 DNA, HCV RNA, and HBV DNA. The donors who had discrepant results between serology and NAT were evaluated with additional tests, including a more sensitive Alternative Nucleic Acid Test, AntiBcore IgM, AntiBcore IgG, HBsAg and Anti HBs. Among 5,083 donors, 331 (6.5%) had at least one positive marker. In multiple logistic regression analysis, the statistically significant factors (adjusted odds ratio and 95% CI) for infection were age 30 years or below [1.45 (1.03, 2.03)], male gender [2.73 (1.64, 4.56)], primary school or lower education [1.56 (1.09, 2.23)], first-time donation [1.82 (1.25, 2.67)], and frequent donation [0.80 (0.70, 0.92)]. The safest donors were females, older than 30 years, with an education more than primary school, and frequent donation. Because of missing responses to some sensitive questions, there remains a need for further improvement of the self-deferral form.

Evaluation of a multiplex human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus nucleic acid testing assay to detect viremic blood donors in northern Thailand

BACKGROUND

Screening of blood donors with nucleic acid testing (NAT) for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) has been implemented recently in the United States. There are limited data, however, on the additional NAT yield of donors in developing countries in Asia where the prevalence of infection is higher. In addition, data on hepatitis B virus (HBV) NAT in high prevalence areas are minimal.

STUDY DESIGN AND METHODS

A total of 5083 whole-blood donors at the Chiang Mai University Hospital, Thailand, blood bank were evaluated with a commercially available NAT assay (Procleix Ultrio, Gen-Probe, Inc.) to screen individual donations.

RESULTS

No NAT yield cases were found for HIV-1 or HCV. There were 17 samples with discrepant HBV DNA NAT and hepatitis B surface antigen (HBsAg) tests, however. Seven of these were HBV DNA NAT-positive, HBsAg-negative; of these 7, 1 was NAT-positive at baseline, but negative on follow-up, and considered a false-positive, 1 had an acute infection, and 5 had chronic prevalent HBV infections, for a NAT yield of 6 in 4798 HBsAg negative donors (1:800). In addition there were 10 NAT-negative, HBsAg-positive serum samples. All were anti-hepatitis B core antigen immunoglobulin G-positive; on testing with a more sensitive NAT target capture assay, 5 were positive (1.8-20.6 IU/mL) and 5 were negative.

CONCLUSION

Multiplex NAT screening of individual-donor serum samples in Northern Thailand detected approximately 1 per 800 HBV NAT-positive, HBsAg-negative donors. The especially high prevalence of HBV infection in Thailand and other Asian countries suggests that HBV NAT screening of donors will be more cost-effective than in other areas.

HLA-B27-associated acute anterior uveitis in the University Referral Centre in North Thailand: clinical presentation and visual prognosis

BACKGROUND

Acute anterior uveitis (AAU) is the most frequent type of uveitis encountered in the west. Although human leucocyte antigen (HLA)-B27-associated ankylosing spondylitis was reported in South East Asia, it is not known whether HLA-B27-associated ocular disease is prevalent in Thailand.

METHODS

A prospective study of 100 unrelated blood donors and 121 consecutive patients with AAU was carried out. All people underwent HLA-B27 typing and full ocular examination. Radiological examination of the sacroiliac joints was conducted in patients with low back pain or arthralgias.

RESULTS

The prevalence of HLA-B27 was 10% among the blood donors in contrast with 44% in the AAU group (p<0.001). The clinical characteristics of HLA-B27-associated AAU were similar to those published throughout the world (unilaterality in 74%, hypopyon in 31%, recurrent AAU in 64%). However, the increased intraocular pressure (IOP) was more common in the HLA-B-27-negative group (p = 0.03) than in their HLA-B27-positive counterparts. At least 15% of the HLA B27-positive group had radiological signs of ankylosing spondylitis.

CONCLUSION

The prevalence of HLA-B27 in the population without uveitis in Thailand is about 10% and clinical characteristics of HLA-B27-positive AAU are similar to those reported in the west. In contrast with earlier reports, HLA-B27-negative AAU in Thailand was associated with increased IOP and should be further studied.

Geographical distribution and disease associations of the CD45 exon 6 138G variant

CD45 is crucial for normal lymphocyte signalling, and altered CD45 expression has major effects on immune function. Both mice and humans lacking CD45 expression are severely immunodeficient, and single-nucleotide polymorphisms in the CD45 gene that cause altered splicing have been associated with autoimmune and infectious diseases. Recently, we identified an exon 6 A138G polymorphism resulting in an increased proportion of activated CD45RO T cells and altered immune function. Here we report a significantly reduced frequency of the 138G allele in hepatitis C Japanese patients and a possibly reduced frequency in type I diabetes. The allele is widely distributed in the Far East and India, indicating that it may have a significant effect on disease burden in a large part of the human population.

HLA class I serotypes and cytotoxic T-lymphocyte responses among human immunodeficiency virus-1-uninfected Thai volunteers immunized with ALVAC-HIV in combination with monomeric gp120 or oligomeric gp160 protein boosting

Antigen-induced cellular immunogenicity may vary between populations due to differences in human leukocyte antigen (HLA) diversity and, hence, may play a critical role in the protection afforded by vaccines. In the setting of two, phase I/II human immunodeficiency virus-1 vaccine trials of a recombinant canarypox prime, and boosting with either recombinant monomeric gp120 or oligomeric gp160, we assessed the association between specific human leukocyte antigen (HLA) class I serotypes and the presence of cytotoxic T-lymphocyte response measured by 51Cr-release assay. HLA class I serotypes A11, A24, A33, B46, and B75 were the most common, present in 10% or more of 245 individuals studied. Forty of 187 (21.4%) Thai adults who received either ALVAC-HIV with gp120 or oligomeric gp160 or ALVAC alone had a precursor cytolytic CD8 T-cell response (pCTL). HLA-B44 was positively and significantly associated with a pCTL response (odds ratio 7.6, 95% CI: 2.7-21.2), whereas B46 was negatively associated but not robust when adjusted for multiple comparisons. Responses to Env proteins accounted for the majority (nine of 11) of pCTL activity among those persons with B44. This HLA class I serotype occurred in 9.4% of participants overall (including the placebo group), less commonly than what is reported from populations of European ancestry. These results strengthen the importance of assessing HLA class I distributions in conjunction with studies of vaccines designed to elicit cellular immunity in different populations.

A CD45 polymorphism associated with abnormal splicing is absent in African populations

The CD45 antigen is essential for normal antigen receptor-mediated signalling in lymphocytes, and different patterns of splicing of CD45 are associated with distinct functions in lymphocytes. Abnormal CD45 splicing has been recognized in humans, caused by a C77G transversion in the gene encoding CD45 (PTPRC). Recently the C77G polymorphism has been associated with multiple sclerosis and increased susceptibility to HIV-1 infection. These studies suggest that the regulation of CD45 splicing may be critical for the proper function of the immune system. Because of these data we examined the frequency of the C77G allele in African and Asian populations from countries with high or low prevalence of HIV infection. Here we report that the variant CD45 C77G allele is absent in African populations. We further show that populations living in the Pamir mountains of Central Asia have a very high prevalence of the C77G variant.

HLA gene frequencies of northern Thais

We investigated the distribution of HLA-A and B locus, gene frequency (GF), antigen frequency (AF), haplotype frequency (HF) and non detectable antigens in Northern Thais. Of 289 native northern Thai people residing in Chiang Mai province for many generations were tested using lymphocytotoxicity test and 146 unrelated subjects were selected for analysis. The common alleles were A2, A11 and A24 for A locus with GF of 36.4%, 35.4% and 15.6%, respectively and B46, B40 and B13 for B locus with GF of 21.1%, 15.7% and 8.6%, respectively. The frequent linkage disequilibrium haplotypes were A2,B46; A33,B17 with HF of 15.9%; 5.0% and LD of 8.3%; 4.6%, respectively (p < 0.0001). The undetectable antigens (blanks) occurred with GF = 11.64% at A locus and GF = 4.92% at B locus. Comparing the GFs to other Thai ethnic groups, showed that the Northern Thais shared several alleles such as A2, A11, B46, and B62 in common with Dai Lue (Thai-speaking people who lived in the southern part of China), (p > 0.05), more than Thais, Thai/Chinese or present-day Thais (p < 0.001). Especially, HLA-B46 with the GF of 21.1% is considered to be a very typical antigen for Southern Mongoloids. These similarities will support the root of migration and origin of Northern Thais.