Search

Background and Objectives: In Japan, the prevalence of haptoglobin deficiency is approximately 1 in 4000. Haptoglobin‐deficient individuals may produce anti‐haptoglobin from allo‐immunization, leading to serious transfusion reactions. Therefore, implementation of a consistent supply of haptoglobin‐deficient fresh frozen plasma is crucial. We developed a novel reagent to facilitate large‐scale identification of haptoglobin‐deficient individuals as potential donors of plasma products. Materials and Methods: We established mouse monoclonal anti‐haptoglobin‐producing cell lines (three clones) using the hybridoma method by immunizing mice with the haptoglobin protein. Purified antibodies were conjugated with carboxylate‐modified polystyrene latex beads and used for haptoglobin measurements by the latex agglutination method using an automatic analyser (LABOSPECT008). Samples with low protein concentrations were re‐examined by enzyme‐linked immunosorbent assay to confirm the results. Additionally, the haptoglobin gene was amplified by polymerase chain reaction to confirm the haptoglobin deletion allele (Hpdel). Results: From February to October 2022, 7476 blood donor samples were screened. Two haptoglobin‐deficient and 21 low‐haptoglobin‐expressing individuals were identified. Two haptoglobin‐deficient donors were found homozygous for Hpdel, and 19 (90%) of the 21 low‐haptoglobin‐expressing individuals were heterozygous for Hpdel, which includes the first reported case of heterozygous Hpdel/HpJohnson. Conclusion: We developed a new reagent for the detection of haptoglobin deficiency, which is automatable and inexpensive and appears useful for large‐scale screening of blood donors. [ABSTRACT FROM AUTHOR]

Background and Objectives: The Xg blood group is composed of two antigens, Xga (XG1) and CD99 (XG2 and MIC2). The XG and CD99 are homologous genes located on pseudoautosomal region 1 of the X and Y chromosomes. The expressions of Xga and CD99 are co‐regulated by a single nucleotide polymorphism (rs311103) in the GATA‐1 binding region. Another mechanism of the Xg(a−) phenotype is the genomic deletion of approximately 114 kb, including the XG gene. Anti‐Xga seems to be naturally occurring by detection in males who have never been transfused. Materials and Methods: In this study, we identified 23 anti‐Xga producers among 580,115 donors (0.004%). Additional 12 anti‐Xga producers were also identified from a separate cohort. Results: All 35 anti‐Xga producers were male. Genomic DNA was obtained from 34 of 35 producers, and all 34 producers were confirmed to carry the XG‐gene‐deficient allele (XGdel). The breakpoints of all 34 producers were identical. The XGdel was also identified in 12 non‐producers of anti‐Xga among 860 donors who have no antibodies against RBCs, and the breakpoints were also identical with the anti‐Xga producers. Conclusion: Our results will serve as the basis for a more complete understanding of Xg blood group polymorphisms. [ABSTRACT FROM AUTHOR]

Background: CD36 is a glycoprotein expressed on platelets and monocytes of the blood. There are two types of CD36 deficiency, type I and type II. Individuals with type I‐deficiency do not express CD36 in any cell type and can produce the CD36 antibody, which causes pathological conditions, such as fetal/neonatal alloimmune thrombocytopenia (FNAIT) and platelet transfusion refractory (PTR), through antigenic exposure via transfusion or pregnancy. Case presentation: We experienced a case of Philadelphia‐positive acute lymphoblastic leukaemia with PTR. In addition to the CD36 antibody, multiple‐specificity HLA antibodies were present in the patient's plasma, requiring transfusion of HLA‐compatible and CD36‐negative platelets (PC‐HLA). Since the number of donors was limited, it was necessary to set‐up a blood transfusion schedule so that hyper‐fractionated cyclophosphamide, vincristine and doxorubicin therapy (hyper‐CVAD) and ponatinib combination chemotherapy could be safely administered to achieve molecular remission. Rituximab administration resulted in reduced levels of both CD36 antibody and HLA antibody. Given the expression of CD36 on haematopoietic stem cells and the limited availability of CD36‐negative PC‐HLA, haematopoietic stem cell transplantation (HSCT) was not considered to be an option. Conclusion: If CD36‐negative, allogeneic haematopoietic stem cell donors are unable to be found, the indications for HSCT in patients with type I CD36‐deficiency should be carefully weighed. In the present case, molecular remission has been able to be maintained to the present day after completion of a two‐year maintenance regimen. [ABSTRACT FROM AUTHOR]

Background: The low‐incidence antigen Sta of the MNS system is usually associated with the GP(B‐A) hybrid molecule, which carries the 'N' antigen at the N terminus. The GP(A‐A) molecule with trypsin‐resistant M antigen has been found in a few St(a+) individuals. Materials and Methods: Among Japanese blood donors, we screened 24 292 individuals for the presence of St(a+) with trypsin‐resistant 'N' antigen and 193 009 individuals for the presence of St(a+) with trypsin‐resistant M antigen. The breakpoints responsible for the Sta antigen were analysed by sequencing the genomic DNAs. Results: A total of 1001 (4·1%) individuals were identified as St(a+) with trypsin‐resistant 'N' antigen. Out of 1001 individuals, 115 were selected randomly for sequencing. Two novel GYP*Sch (GYP*401) variants with new intron 3 breakpoints of GYPA were detected in three cases. Twenty‐five (0·013%) individuals were identified as St(a+) with trypsin‐resistant M antigen. Five individuals had the GYP(A‐ψB‐A) hybrid allele; two of these five individuals were GYP*Zan (GYP*101.01), and the remaining three had a novel GYP(A‐ψB‐A) allele with the first breakpoint in GYPA exon A3 between c.178 and c.203. Nine individuals had a novel GYP(A‐E‐A) allele with GYPE exon E2 and pseudoexon E3 instead of GYPA exon A2 and A3. The 11 remaining individuals had a novel GYP(A‐A) allele with a 9‐bp deletion that included the donor splice site of intron 3 of GYPA. Conclusion: Our finding on diversity of glycophorin genes responsible for Sta antigen provides evidence for further complexity in the MNS system. [ABSTRACT FROM AUTHOR]

Background and objectives: MNS is a highly polymorphic blood group comprising 49 antigens recognized by International Society of Blood Transfusion, some of which may have been generated by genomic recombination among the closely linked genes GYPA, GYPB and GYPE. The GYPE gene has an almost identical sequence to GYPA*01 allele in exon 2 (99% homology), which accounts for M antigen. We investigated an unusual glycophorin molecule with protease‐resistant M antigen. Methods: Blood samples were screened by an automated blood typing system (PK7300) using bromelain‐treated red blood cells (RBCs) and murine monoclonal anti‐M. The M‐positive RBC samples were analysed by immunoblotting using anti‐M as the primary antibody. GYPA, GYPB and GYPE genes were analysed by polymerase chain reaction (PCR), cloning and sequencing using reticulocyte mRNA and genomic DNA. Results: Serological tests and immunoblotting revealed that 103 of the 193 009 individuals (0·0534%) expressed protease‐resistant M‐active glycophorin having a molecular weight of 20 kDa. All the 103 individuals were S+ s− or S− s+. When reticulocyte mRNA from the individuals with M‐active glycophorin (20 kDa) was examined by PCR and cloning followed by sequencing, a novel GYPE‐B hybrid transcript was identified. Long‐range PCR and sequencing using genomic DNA revealed that the individuals had a GYPB‐E(2‐4)‐B hybrid gene. This hybrid gene was predicted to encode a 59‐amino‐acid mature glycoprotein that expresses no S or s antigens Conclusions: The prevalence of the M‐active glycophorin (20 kDa) in the Japanese population is 0·0534%. This glycophorin is predicted to be a 59 amino acids polypeptide encoded by the novel GYPB‐E(2‐4)‐B hybrid gene. [ABSTRACT FROM AUTHOR]

Background: The XG blood group system comprises two antigens, Xg a and CD99. CD99 is known to be carried on both the X and Y chromosomes in pseudoautosomal region 1. We identified five unrelated Japanese individuals with anti-CD99 and investigated their genomic background as well as the clinical significance of anti-CD99., Study Design and Methods: Analysis of CD99 expression on RBCs and a modified monocyte monolayer assay was performed using flow cytometry. Genomic DNA was obtained from the five anti-CD99 producers to identify the deleted region responsible for the lack of CD99, and we conducted a long polymerase chain reaction using primer pairs specific for CD99 and GYG2., Results: CD99 expression from the Y chromosome was higher than that from the X chromosome. The five anti-CD99 plasma samples gave varied agglutination strengths with the red blood cells (RBCs) expressing high and low CD99 levels, in the antiglobulin test. The phagocytosis rate of anti-CD99-sensitized RBCs was 76.6% in one case indicating a risk of hemolytic transfusion reactions (HTR), and it correlated with the level of CD99 expression. The deleted region spanned 115 kb, from CD99 exon 3 to GYG2 exon 1. All five anti-CD99 producers were homozygous for the large deletion allele., Discussion: All five anti-CD99 producers were females with a history of pregnancy in Kyushu, Japan, and this deletion allele may thus be endemic. Our results indicated the possibility of HTR due to anti-CD99, and the risk is low when transfusing RBC products from Xg(a-) females with a low expression of CD99., (© 2025 AABB.)