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- Jongruamklang, Philaiphon, et al.
(författare)
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Characterization of GYP*Mur and novel GYP*Bun-like hybrids in Thai blood donors reveals a qualitatively altered s antigen
- 2020
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Ingår i: Vox Sanguinis. - : Wiley. - 0042-9007 .- 1423-0410. ; 115:5, s. 472-477
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Tidskriftsartikel (refereegranskat)abstract
- Background and objectives: The Mi(a+) GP(B-A-B) hybrid phenotypes occur with a prevalence of 2%–23% across Southeast Asia. While the s antigen is alleged to be altered, no evidence for specific variants is known. Screening using a monoclonal IgM anti-s mistyped six S‒s+ RBC units as S‒s‒. Further, alloanti-s was identified in an S+s+ patient. Our objective was to investigate the s antigen further. Materials and methods: DNA from 63 Thai blood donor samples PCR-positive for a GYP(B-A-B) hybrid was sequenced with primers spanning GYPB exons 3–4. Flow cytometry was used for semiquantitative analysis of s expression and correlated with the glycophorin genotype. Results: DNA sequencing showed that GYP*Mur was carried by 56/63 samples (88·9%) of which 5/56 lacked normal GYPB: three of these were GYP*Mur homozygotes, one was a compound heterozygote carrying GYP*Mur and a GYP*Bun-like allele (designated GYP*Thai), and the fifth sample carried GYP*Mur and another GYP*Bun-like allele. Seven samples (7/63) were GYP*Thai heterozygotes. IgM monoclonal anti-s (P3BER) did not react with the s antigen carried by GP.Mur or GP.Bun, whereas two IgG anti-s showed enhanced reactivity. Conclusions: We confirmed that GYP*Mur is the most frequent variant in Thai blood donors and also identified GYP*Thai with a frequency of 1·1%. We showed that s antigen on Mi(a+) GP(B-A-B) hybrids is qualitatively altered and should be considered when selecting reagents for phenotyping where such hybrids are prevalent, endemically and in blood centres worldwide.
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| 2. |
- Jongruamklang, Philaiphon, et al.
(författare)
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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of 36 blood group alleles among 396 Thai samples reveals region-specific variants
- 2018
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Ingår i: Transfusion. - : Wiley. - 0041-1132 .- 1537-2995. ; 58:7, s. 1752-1762
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Blood group phenotype variation has been attributed to potential resistance to pathogen invasion. Variation was mapped in blood donors from Lampang (northern region) and Saraburi (central region), Thailand, where malaria is endemic. The previously unknown blood group allele profiles were characterized and the data were correlated with phenotypes. The high incidence of the Vel-negative phenotype previously reported in Thais was investigated. STUDY DESIGN AND METHODS: DNA from 396 blood donors was analyzed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Outliers were investigated by serology and DNA sequencing. Allele discrimination assays for SMIM1 rs1175550A/G and ACKR1 rs118062001C/T were performed and correlated with antigen expression. RESULTS: All samples were phenotyped for Rh, MNS, and K. Genotyping/phenotyping for RhD, K, and S/s showed 100% concordance. Investigation of three RHCE outliers revealed an e-variant antigen encoded by RHCE*02.22. Screening for rs147357308 (RHCE c.667T) revealed a frequency of 3.3%. MN typing discrepancies in 41 samples revealed glycophorin variants, of which 40 of 41 were due to Mia. Nine samples (2.3%) were heterozygous for FY*01W.01 (c.265C>T), and six samples (1.5%) were heterozygous for JK*02N.01. All samples were wildtype SMIM1 homozygotes with 97% homozygosity for rs1175550A. CONCLUSIONS: Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry is an efficient method for rapid routine genotyping and investigation of outliers identified novel variation among our samples. The expected high prevalence of the Mi(a+) phenotype was observed from both regions. Of potential clinical relevance in a region where transfusion-dependent thalassemia is common, we identified two RHCE*02 alleles known to encode an e-variant antigen.
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| 3. |
- Jongruamklang, Philaiphon, et al.
(författare)
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Platelets inhibit erythrocyte invasion by Plasmodium falciparum at physiological platelet:erythrocyte ratios
- 2022
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Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 32:2, s. 168-174
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the effect of platelet:erythrocyte (P:E) ratios on Plasmodium falciparum erythrocyte invasion.BACKGROUND: Recent reports have shown that platelets are directly involved in the immune response towards P. falciparum during erythrocyte invasion. However, the literature both supports and conflicts with a role for platelets in limiting invasion. Also, the effect of platelet numbers on invasion (parasitemia) has not been thoroughly investigated.METHODS/MATERIALS: The P. falciparum strains FCR3S1.2 and W2mef were cultured with group O erythrocytes. The cultures were synchronised and supplemented with pooled platelets at P:E ratios ranging from 1:100 to 1:2. Parasitemia was measured at 40 h by flow cytometry and by microscopy of blood smears.RESULTS: A linear relationship was observed between reduced invasion and increased platelet numbers at P:E ratios ranging from 1:100 to 1:20. However, this effect was reversed at lower ratios (1:10-1:2). Microscopic evaluation revealed aggregation and attachment of platelets to erythrocytes, but not specifically to parasitised erythrocytes.CONCLUSION: We have shown that under physiological P:E ratios (approx. 1:10-1:40), platelets inhibited P. falciparum invasion in a dose-dependent manner. At ratios of 1:10 and below, platelets did not further increase the inhibitory effect and, although the trend was reversed, inhibition was still maintained.
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| 4. |
- Jongruamklang, Philaiphon
(författare)
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Studies of Thai blood group and platelet polymorphism. Implications for malaria susceptibility.
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objectives of the thesis were to seek a better understanding of polymorphic RBC surface molecules in the Thai, and to investigate the role of certain blood groups in malarial invasion. MALDI-TOF MS was employed in Study I as an efficient method for genotyping to establish the common blood group and platelet antigen genotypes of 396 blood donors. Investigation of outliers identified variation among these samples, both expected and novel. The expected high prevalence of the Mi(a+) phenotype was observed, and identified that 2.3% of samples carried FY c.265T, a polymorphism carried on FY*01 instead of FY*02 as found in the Caucasians. Of potential clinical relevance in a region where transfusion-dependent thalassemia is common, we identified two RHCE*02 alleles known to encode an e-variant antigen. Allelic discrimination assays for extended testing of platelet polymorphism predicted the expected antigen distribution for Southeast Asia. In Study II, homozygosity for a novel nonsense mutation (c.420T>G) in B3GALNT1 (GLOB*01N.13) was identified in two Thai sisters suffering from recurrent spontaneous abortions due to the Pk phenotype, adding to the twelve null alleles already known in the GLOB system. Screening of the blood donor cohort revealed another individual carrying this allele, suggesting regional occurrence of this rare allele. In Study III, DNA sequencing not only confirmed that GYP*Mur is the most frequent allele of the variant glycophorin genes in Thai blood donors, but also identified a GYP*Bun-like allele (designated GYP*Thai) that was shown to be relatively common (MAF = 0.01) in this group. These hybrid alleles have a previously uncharacterized effect on s antigen expression on RBCs, qualitatively and quantitatively, that has implications for reagent selection in transfusion medicine. Study IV turned to platelets, which showed an inhibitory effect on RBC invasion by P. falciparum under physiological platelet:RBC ratios (approx. 1:10 - 1:40) in a dose-dependent manner and that was still effective at levels considered to be thrombocytopenic. At higher platelet concentrations, the trend was reversed so that platelets did not increase the inhibitory effect on RBC invasion further. However, platelet-dependent killing, as witnessed by increased extracellular parasites, remained effective. Despite all we know about blood group polymorphism, much remains to learn. This thesis has explored allelic variation in a region of the world where malaria has long been endemic and the observed blood cell traits highlight our intriguing ability to adapt.
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