International Society of Blood Transfusion Working Party on Red Cell Immunogenetics and Blood Group Terminology: Report of the Dubai, Copenhagen and Toronto meetings

CRISPR-Cas9-driven antigen conversion of clinically relevant blood group systems

The common practice of blood transfusion entirely relies on blood donations from the population. Ensuring blood group compatibility between a donor and a recipient is paramount to prevent critical adverse reactions. Finding compatible blood can be challenging given the high diversity of blood group antigens, especially for chronically transfused patients at higher risk of alloimmunization owing to repeated exposures to foreign RBCs. In addition, due to the immunogenicity of the ABO blood group and the highly polymorphic nature of the Rhesus (Rh) system, they both remain of prime importance in transfusion medicine. Cultured red blood cells (cRBCs) may eventually provide an alternative for blood donations-at least in some circumstances. Combining cRBCs with blood group gene editing could broaden transfusion accessibility by making antigen expression compatible with rare phenotypes, thus meeting the needs of more patients. Starting from mobilized, erythroid-primed hematopoietic stem and progenitor cells (HSPCs), we used virus- and selection-free, CRISPR-Cas9-mediated knockouts to produce erythroid cells devoid of AB and Rh antigen. The approach yielded almost complete conversion to O- and RhNull phenotypes, as determined by standard hemagglutination and flow cytometry analyses. Combined with robust cRBC protocols, these clinically relevant phenotypic changes could eventually expand the accessibility of blood transfusion for specific and unmet clinical needs.

An update on the RHAG blood group system

This update on the RHAG blood group system (ISBT 030) (Chou ST, Westhoff CM. The Rh and RhAG blood group systems. Immunohematology 2010;26:178-86) reports the addition of three new low-prevalence antigens carried on the Rh-associated glycoprotein (RhAG). Kg (previously 700045; now RHAG5) has been demonstrated to be antithetical to the previously described high-prevalence DSLK (RHAG3). Two further low-prevalence antigens (RHAG6 and RHAG7) are described, both resulting from rare missense RHAG mutations encoding amino acid changes predicted to be externally located. All three new low-prevalence antigens have been implicated in hemolytic disease of the fetus and newborn. The RHAG system now comprises six antigens, two of high prevalence and four of low prevalence, including one antithetical pair. RHAG4 has been made obsolete.

Serologic and molecular identification of the variation on ABO*B.01 gene in ABO glycosyltransferases associated with Bw phenotype: a case report

AB antigen is formed by glycosyltransferase enzyme, which catalyzes the corresponding substrates to be connected to the galactose of the precursor substance H antigen. To study the effect of the α-1,3-D galactosyltransferase (GTB) gene mutation on B antigen expression, we explored its molecular mechanism by combining molecular biological methods with bioinformatics. The ABO blood type of the patients was identified using conventional serologic methods, and the polymerase chain reaction (PCR) products of exons 1-7 of the ABO gene were directly sequenced using gene-specific primers and direct sequencing. Proteins in the secretory supernatant of transfected cells were collected in vitro, and GTB content was quantitatively analyzed using western blotting. Bioinformatics software was used to simulate the 3-dimensional structure of the mutant protein. In this case, the patient's serologic test results revealed subtype B. Gene sequencing results confirmed a mutation at base 278 of exon 6. The mutation (c.278C>T) changed the 93rd amino acid of the protein polypeptide chain from proline to leucine (p.P93L). The variant p.P93L did not affect the expression and secretion of GTB, but affected enzyme activity and stability, ultimately manifesting as weakened expression of the B antigen and reduced affinity.

Examination of the relationship between ABO/Rh blood groups and dietary compliance in children with coeliac disease: A single-centre experience

AIM

Coeliac disease (CD) is an autoimmune enteropathy that develops upon ingestion of food containing gluten. The established link between ABO blood groups and numerous infectious and non-infectious illnesses prompted this investigation into blood group distribution and its relationship with dietary compliance among children diagnosed with CD.

METHODS

In this retrospective study, patients with CD who were followed for ≥1 year at the paediatric gastroenterology outpatient clinic of our hospital were evaluated. History, physical examination and coeliac serology results were reviewed for each patient. Patients were divided into two groups based on self-reported compliance to a gluten-free diet: diet-adherent and non-diet-adherent. Patient and control groups were examined in terms of ABO blood groups.

RESULTS

A total of 177 patients with CD were included in the study. A control group of 211 age- and sex-matched children without any chronic disease who had undergone blood group testing for various reasons was included for comparison. A total of 65% (n = 115) of the patients were girls, and 35% (n = 62) were boys. No significant relationship was found between CD diagnosis and ABO blood groups among patients (P = 0.559). Furthermore, the dietary compliance status of the patients was not associated with any specific blood group (P = 0.951).

CONCLUSION

No notable difference was found between patients with CD with or without gluten-free diet compliance in terms of the distribution of ABO blood groups and Rhesus (Rh) factor. Therefore, it can be inferred that all blood groups and subgroups carry an equal risk for CD.

A Review of the Knops Blood Group System

The Knops blood group system is an independent blood group system recognized by International Society of Blood Transfusion (ISBT) in 1992, and latest time consisting of 13 antigens carried on a glycoprotein of 2489 amino acids and called the Complement C3b/C4b Receptor 1 (CR1). Erythrocyte KN antigen was first reported in 1970, and CR1 is a protein coding gene that is a member of the receptors of complement activation (RCA) family and is located in the "cluster RCA" region of chromosome 1. CR1 is an important participant in the erythrocyte immune machinery and plays an major role in inhibiting complement activation, and polymorphisms in its expression have been closely associated with a variety of diseases, including systemic lupus erythematosus (SLE), malaria, Plasmodium falciparum malaria, Alzheimer's disease (AD) and leprosy. Antibodies to the Knops system usually do not bind to complement and do not cause a hemolytic reaction. However, anti-Knops antibodies can be detected in the serum of some pregnant women. Generally, however, they only test positive by direct antiglobulin test (DAT) and most of them do not cause hemolytic disease of the newborn (HDN). This article is a review of the progress of the Knops blood group system.

Whispers in the Blood: Leveraging MicroRNAs for Unveiling Autologous Blood Doping in Athletes

The prevalence of autologous blood transfusions (ABTs) presents a formidable challenge in maintaining fair competition in sports, as it significantly enhances hemoglobin mass and oxygen capacity. In recognizing ABT as a prohibited form of doping, the World Anti-Doping Agency (WADA) mandates stringent detection methodologies. While current methods effectively identify homologous erythrocyte transfusions, a critical gap persists in detecting autologous transfusions. The gold standard practice of longitudinally monitoring hematological markers exhibits promise but is encumbered by limitations. Despite its potential, instances of blood doping often go undetected due to the absence of definitive verification processes. Moreover, some cases remain unpenalized due to conservative athlete-sanctioning approaches. This gap underscores the imperative need for a more reliable and comprehensive detection method capable of unequivocally differentiating autologous transfusions, addressing the challenges faced in accurately identifying such prohibited practices. The development of an advanced detection methodology is crucial to uphold the integrity of anti-doping measures, effectively identifying and penalizing instances of autologous blood transfusion. This, in turn, safeguards the fairness and equality essential to competitive sports. Our review tackles this critical gap by harnessing the potential of microRNAs in ABT doping detection. We aim to summarize alterations in the total microRNA profiles of erythrocyte concentrates during storage and explore the viability of observing these changes post-transfusion. This innovative approach opens avenues for anti-doping technologies and commercialization, positioning it as a cornerstone in the ongoing fight against doping in sports and beyond. The significance of developing a robust detection method cannot be overstated, as it ensures the credibility of anti-doping efforts and promotes a level playing field for all athletes.

Elucidation of the low-expressing erythroid CR1 phenotype by bioinformatic mining of the GATA1-driven blood-group regulome

Genetic determinants underlying most human blood groups are now clarified but variation in expression levels remains largely unexplored. By developing a bioinformatics pipeline analyzing GATA1/Chromatin immunoprecipitation followed by sequencing (ChIP-seq) datasets, we identify 193 potential regulatory sites in 33 blood-group genes. As proof-of-concept, we aimed to delineate the low-expressing complement receptor 1 (CR1) Helgeson phenotype on erythrocytes, which is correlated with several diseases and protects against severe malaria. We demonstrate that two candidate CR1 enhancer motifs in intron 4 bind GATA1 and drive transcription. Both are functionally abolished by naturally-occurring SNVs. Erythrocyte CR1-mRNA and CR1 levels correlate dose-dependently with genotype of one SNV (rs11117991) in two healthy donor cohorts. Haplotype analysis of rs11117991 with previously proposed markers for Helgeson shows high linkage disequilibrium in Europeans but explains the poor prediction reported for Africans. These data resolve the longstanding debate on the genetic basis of inherited low CR1 and form a systematic starting point to investigate the blood group regulome.

Lack of the human choline transporter-like protein SLC44A2 causes hearing impairment and a rare red blood phenotype

Blood phenotypes are defined by the presence or absence of specific blood group antigens at the red blood cell (RBC) surface, due to genetic polymorphisms among individuals. The recent development of genomic and proteomic approaches enabled the characterization of several enigmatic antigens. The choline transporter-like protein CTL2 encoded by the SLC44A2 gene plays an important role in platelet aggregation and neutrophil activation. By investigating alloantibodies to a high-prevalence antigen of unknown specificity, found in patients with a rare blood type, we showed that SLC44A2 is also expressed in RBCs and carries a new blood group system. Furthermore, we identified three siblings homozygous for a large deletion in SLC44A2, resulting in complete SLC44A2 deficiency. Interestingly, the first-ever reported SLC44A2-deficient individuals suffer from progressive hearing impairment, recurrent arterial aneurysms, and epilepsy. Furthermore, SLC44A2_null individuals showed no significant platelet aggregation changes and do not suffer from any apparent hematological disorders. Overall, our findings confirm the function of SLC44A2 in hearing preservation and provide new insights into the possible role of this protein in maintaining cerebrovascular homeostasis.

Molecular and structural characterization of a novel high-prevalence antigen of the Augustine blood group system

BACKGROUND

An antibody directed against a high-prevalence red blood cell (RBC) antigen was detected in a 67-year-old female patient of North African ancestry with a history of a single pregnancy and blood transfusion. So far, the specificity of the proband's alloantibody remained unknown in our immunohematology reference laboratory.

STUDY DESIGN AND METHODS

Whole-exome sequencing (WES) was performed on the proband's DNA. The reactivity to the SLC29A1-encoded ENT1 adenosine transporter was investigated by flow cytometry analyses of ENT1-expressing HEK293 cells, and RBCs from Augustine-typed individuals. Erythrocyte protein expression level, nucleoside-binding capacity, and molecular structure of the proband's ENT1 variant were further explored by western blot, flow cytometry, and molecular dynamics calculations, respectively.

RESULTS

A missense variant was identified in the SLC29A1 gene, which encodes the Augustine blood group system. It arises from homozygosity for a rare c.242A > G missense mutation that results in a nonsynonymous p.Asn81Ser substitution within the large extracellular loop of ENT1. Flow cytometry analyses demonstrated that the proband's antibody was reactive against HEK-293 cells transfected with control but not proband's SLC29A1 cDNA. Consistent with this finding, proband's antibody was found to be reactive with At(a-) (AUG:-2), but not AUG:-1 (null phenotype) RBCs. Data from structural analysis further supported that the proband's p.Asn81Ser variation does not alter ENT1 binding of its specific inhibitor NBMPR.

CONCLUSION

Our study provides evidence for a novel high-prevalence antigen, AUG4 (also called ATAM after the proband's name) in the Augustine blood group system, encoded by the rare SLC29A1 variant allele AUG*04 (c.242A > G, p.Asn81Ser).

Alloantigen Copy Number as a Critical Factor in RBC Alloimmunization

RBC alloimmunization remains a significant barrier to ongoing transfusion therapy leading to morbidity, and in extreme cases mortality, due to delayed or insufficient units of compatible RBCs. In addition, the monitoring and characterization of alloantibodies, often with multiple specificities in a single patient, consumes substantial health care resources. Extended phenotypic matching has mitigated, but not eliminated, RBC alloimmunization and is only logistically available for specialized populations. Thus, RBC alloimmunization remains a substantial problem. In recent decades it has become clear that mechanisms of RBC alloimmunization are distinct from other antigens and lack of mechanistic understanding likely contributes to the fact that there are no approved interventions to prevent RBC alloimmunization from transfusion. The combination of human studies and murine modeling have identified several key factors in RBC alloimmunization. In both humans and mice, immunogenicity is a function of alloantigen copy number on RBCs. Murine studies have further shown that copy number not only changes rates of immunization but the mechanisms of antibody formation. This review summarizes the current understanding of quantitative and qualitative effects of alloantigen copy number on RBC alloimmunization.

Intestinal mucin-type O-glycans: the major players in the host-bacteria-rotavirus interactions

Rotavirus (RV) causes severe diarrhea in young children and animals worldwide. Several glycans terminating in sialic acids (SAs) and histo-blood group antigens (HBGAs) on intestinal epithelial cell (IEC) surface have been recognized to act as attachment sites for RV. IECs are protected by the double layer of mucus of which O-glycans (including HBGAs and SAs) are a major organic component. Luminal mucins, as well as bacterial glycans, can act as decoy molecules removing RV particles from the gut. The composition of the intestinal mucus is regulated by complex O-glycan-specific interactions among the gut microbiota, RV and the host. In this review, we highlight O-glycan-mediated interactions within the intestinal lumen prior to RV attachment to IECs. A better understanding of the role of mucus is essential for the development of alternative therapeutic tools including the use of pre- and probiotics to control RV infection.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

International Society of Blood Transfusion Working Party on Red Cell Immunogenetics and Blood Group Terminology Report of Basel and three virtual business meetings: Update on blood group systems

BACKGROUND AND OBJECTIVES

Under the ISBT, the Working Party (WP) for Red Cell Immunogenetics and Blood Group Terminology is charged with ratifying blood group systems, antigens and alleles. This report presents the outcomes from four WP business meetings, one located in Basel in 2019 and three held as virtual meetings during the COVID-19 pandemic in 2020 and 2021.

MATERIALS AND METHODS

As in previous meetings, matters pertaining to blood group antigen nomenclature were discussed. New blood group systems and antigens were approved and named according to the serologic, genetic, biochemical and cell biological evidence presented.

RESULTS

Seven new blood group systems, KANNO (defined numerically as ISBT 037), SID (038), CTL2 (039), PEL (040), MAM (041), EMM (042) and ABCC1 (043) were ratified. Two (039 and 043) were de novo discoveries, and the remainder comprised reported antigens where the causal genes were previously unknown. A further 15 blood group antigens were added to the existing blood group systems: MNS (002), RH (004), LU (005), DI (010), SC (013), GE (020), KN (022), JMH (026) and RHAG (030).

CONCLUSION

The ISBT now recognizes 378 antigens, of which 345 are clustered within 43 blood group systems while 33 still have an unknown genetic basis. The ongoing discovery of new blood group systems and antigens underscores the diverse and complex biology of the red cell membrane. The WP continues to update the blood group antigen tables and the allele nomenclature tables. These can be found on the ISBT website (http://www.isbtweb.org/working-parties/red-cell-immunogenetics-and-blood-group-terminology/).

Hemolytic disease of the fetus and newborn caused by anti-sD antibody in a GP.Mur/Mur Thai mother and review of the prevalence of sD in Thai blood donors

BACKGROUND

Low-prevalence antigen s^D (MNS23) is encoded by GYPB c.173C > G. Hemolytic disease of the fetus and newborn (HDFN) due to anti-s^D is rare. A mother delivered a newborn whose red blood cells (RBCs) were DAT-positive and was later diagnosed with HDFN. Serum from the mother was incompatible with the father's RBCs and was used to screen 184 Thai blood donors. This study aimed to investigate the cause of HDFN in a Thai family and determine the prevalence of s^D in Thai blood donors.

MATERIALS AND METHODS

Three family members and four blood donors were investigated in the study. Massively Parallel Sequencing (MPS) was used for genotyping. Standard hemagglutination techniques were used in titration studies, phenotyping, and enzyme/chemical studies. Anti-s, anti-Mi^a , anti-JENU, and anti-s^D reagents were used in serological investigations.

RESULTS

The mother was GYP*Mur/Mur. The father and the four donors were GYPB*s/s^D predicting S - s + s^D +. The baby was GYP*Mur/sD and his RBCs were Mi^a +, s + ^w with anti-s (P3BER) and JENU+^w . RBCs from two GYPB*s^D -positive blood donors reacted with anti-s^D (Dreyer). Proteolytic enzyme α-chymotrypsin-treated s^D + cells did not react with anti-s^D (Wat) produced by the GP.Mur/Mur mother but reacted with the original anti-s^D (Dreyer).

DISCUSSION

This is the first report of HDFN due to anti-s^D in the Asian population. The genotype frequency for GYPB*s^D in a selected Thai blood donor population is 2.2% (4/184). Anti-s^D should be considered in mothers with Southeast Asian or East Asian background when antibody identification is unresolved in pregnancies affected by HDFN.

YTGT: A new high-prevalence antigen in the Yt blood group system in two unrelated Native Americans and transfusion management

BACKGROUND

The Yt system consists of five antigens: antithetical Yt^a /Yt^b and the high-prevalence antigens YTEG, YTLI, and YTOT. We investigated a sample from a Native American (NA) female with post-operative anemia and an unidentified antibody who developed rigors, tachycardia, and hypotension on transfusion of incompatible RBCs.

METHODS AND MATERIALS

Serologic testing methods included LISS, PEG, and IgG gel. Test RBCs were treated with papain, trypsin, alpha-chymotrypsin, 2-amino-ethylisothiouronium, and dithiothreitol. Rare RBCs were tested, and inhibition studies were performed. DNA extracted from WBCs was used for Sanger sequencing.

RESULTS

Initial testing showed strong 3-4+ plasma reactivity with all panel cells at LISS IAT; auto control was negative. Positive reactions were observed with numerous rare RBCs except for PNH-III, which lack GPI-linked DO, Yt, CROM, JMH, and Emm. Enzyme sensitivity patterns suggest Yt specificity, and soluble recombinant srYt neutralized reactivity. ACHE sequencing revealed YT*A/A genotype but with a homozygous change in exon 2, c.290A>G (p.Gln97Arg). Antibody reactivity was reminiscent of that seen in an unrelated NA male investigated previously. His RBCs were nonreactive with her plasma. ACHE carried the same c.290G/G change.

CONCLUSION

Two unrelated NA patients were found to have an antibody to a new high-prevalence Yt antigen, designated YTGT (YT6), associated with a clinically significant transfusion reaction. Identification of the specificity relied on enzyme sensitivity, use of PNH-III RBCs, neutralization using soluble recombinant Yt, and the finding of a novel change in ACHE, c.290A>G (p.Gln97Arg), designated YT*01. ̶ 06. IVIG and steroids were used to mitigate further reactions to transfusion.

Frequency of Extended Red Cell Antigen Phenotype Among Patients of Hematological Diseases: A Single Center Study

Background

Alloimmunization of erythrocytes is a major problem in patients with hematological diseases that require frequent blood transfusions. Matching of extended red cell antigens of Kell, MNS, Kidd, and Duffy can decrease the risk of alloimmunization. Hence, in this study, the frequencies of the extended red cell phenotypes were explored.

Objective

To find out the frequency of extended red blood cell antigen phenotypes among patients with hematological diseases.

Methods

This cross-sectional research study was performed on 488 patients diagnosed with hematological diseases who required blood transfusion at the National Institute of Blood Disease and Bone Marrow Transplantation Karachi for a period of 1.42 years from November 2019 to March 2021. The blood of patients was analyzed for antigen phenotypes of different blood group systems including Kell, MNS, Kidd, and Duffy. The data obtained were interpreted.

Results

Among the 488 patients, 284 (58.20%) patients were male, and 204 (41.80%) patients were female with a mean age of 8.1 years. Beta thalassemia was the most common hematological disease reported in 354 (72.5%) of the patients. The most common blood group was O positive reported in 182 (37.3%) of the patients followed by B positive blood group in 124 (25.4%). The frequencies of extended red cell antigen phenotypes in the patients were K antigen 14 (2.9%), Kp^a antigen 26 (5.3%), Kp^b antigen 424 (86.9%), Fy^a antigen 360 (73.8%), Fy^b antigen 260 (53.3%), Jk^a antigen 294 (60.2%), Jk^b antigen 326 (66.8%), M antigen 410 (84.0%) and N antigen 306 (62.7%).

Conclusion

Beta thalassemia was the most common hematological disease followed by iron deficiency anemia, aplastic anemia, and acute leukemia. Patients with hematological diseases had a higher prevalence of Kp^b antigen followed by M, Fy^a, Jk^b, N, Jk^a, Fy^b, Kp^a, and K antigen. O positive was the most frequent blood group followed by B positive, A positive and AB positive blood group.

Transfusion support for a woman with RHD*09.01.02 and the novel RHD*01W.161 allele in trans

According to recent work group recommendations, individuals with the serologic weak D phenotypes should be RHD genotyped and individuals with molecular weak D types 1, 2, 3, 4.0, or 4.1 should be treated as D+. We report an African American woman with a long-standing history of metrorrhagia, who presented for infertility evaluation. Blood grouping showed AB with a possible subgroup of A, based on mixed-field agglutination, and a serologic weak D phenotype. Results from routine red cell genotyping for the RHD gene was incongruent with the serologic RhCE phenotype. For the surgical procedure, the patient was hence scheduled to receive group AB, D- RBC transfusions. Subsequent molecular analysis identified the ABO*A2.01 and ABO*B.01 alleles for the ABO genotype and the novel RHD allele [NG_007494.1(RHD):c.611T>A] along with an RHD*09.01.02 allele for the RHD genotype. Using a panel of monoclonal anti-D reagents, we showed the novel RHD(I204K) allele to represent a serologic weak D phenotype, despite occurring as a compound heterozygote, designated RHD*weak D type 161 (RHD*01W.161). Individuals with a weak D type 4.2 allele are prone to anti-D immunization, while the immunization potential of novel RHD alleles is difficult to predict. For now, patients should be treated as D- in transfusion and pregnancy management, when they harbor a novel RHD allele along with any weak D allele other than weak D types 1, 2, 3, 4.0, or 4.1. This study exemplifies strategies for how and when a laboratory should proceed from routine genotyping to nucleotide sequencing before any decisions on transfusion practice is made.

Using Whole Genome Sequencing to Characterize Clinically Significant Blood Groups Among Healthy Older Australians

There have been no comprehensive studies of a full range of blood group polymorphisms within the Australian population. This problem is compounded by the absence of any databases carrying genomic information on chronically transfused patients and low frequency blood group antigens in Australia. Here, we use RBCeq, a web server–based blood group genotyping software, to identify unique blood group variants among Australians and compare the variation detected vs global data. Whole-genome sequencing data were analyzed for 2796 healthy older Australians from the Medical Genome Reference Bank and compared with data from 1000 Genomes phase 3 (1KGP3) databases comprising 661 African, 347 American, 503 European, 504 East Asian, and 489 South Asian participants. There were 661 rare variants detected in this Australian sample population, including 9 variants that had clinical associations. Notably, we identified 80 variants that were computationally predicted to be novel and deleterious. No clinically significant rare or novel variants were found associated with the genetically complex ABO blood group system. For the Rh blood group system, 2 novel and 15 rare variants were found. Our detailed blood group profiling results provide a starting point for the creation of an Australian blood group variant database.

Red blood cell alloimmunization in pregnancy: A 10-year single-center study

Background/Aim. Pregnancy-induced red blood cell (RBC) alloimmunization is important not only because of the possible negative effects on subsequent pregnancy outcomes in case the fetus carries the antigen but also because of the optimal trans-fusion management in cases of obstetric hemorrhage. Timely detection of RBC antibodies is part of testing, prevention, and treatment strategy, aimed at achieving better outcomes for alloimmunized mothers with an affected fetus. The aim of the study was to determine the frequency and specificity of alloantibodies among pregnant women from the South Backa District, Serbia, with special attention to the incidence of anti-D alloantibodies. Methods. A retrospective study was conducted in the Blood Transfusion Institute of Vojvodina and covered the period from January 1, 2010, to December 31, 2019. Screening and antibody identification were performed by an indirect antiglobulin test in gel-microcards (ID-Card Liss/Coombs) with two test RBC (ID-DiaCell I-II screening cells, Bio-Rad, Cressier, Switzerland) on an automated system (IH-500, Bio-Rad). Results. Among 25,694 tested pregnant women, 1.38% were actively immunized, while 1.12% of women acquired antibodies in the current pregnancy. Among 3,622 (14.09%) RhD-negative women, 1.77% produced anti-D antibodies during the ongoing pregnancy. Distribution of anti-body specificity was: anti-D 23.34%, anti-M 11.85%, anti-E 9.41%, anti-K 9.41%, anti-C 5.92%, anti-Fyb 5.92%, anti-c 3.13%, anti-S 3.13%, anti-Lea 3.13%, anti-Leb 3.13%, anti-Cw 1.75%, anti-Jka 1.40%, anti-P 1.05%, anti-Lub 0.70%, anti-Fya 0.35%, autoantibody of undetermined specificity 0.70%, and irregular antibodies of undetermined specificity 15.68%. Conclusion. Immunoglobulin prophylaxis has led to a significant reduction in the frequency of D-alloimmunization among pregnant women in the South Backa District over the last ten years. However, the incidence of anti-D antibodies is still significantly higher than in published data for developed countries. We also identified the other, less commonly present, clinically significant antibodies. There is a need to introduce uniform recommendations for immunohematological testing in pregnancy on the territory of the Republic of Serbia in accordance with modern requirements.

BGvar: A comprehensive resource for blood group immunogenetics

BACKGROUND

Blood groups form the basis of effective and safe blood transfusion. There are about 43 well-recognised human blood group systems presently known. Blood groups are molecularly determined by the presence of specific antigens on the red blood cells and are genetically determined and inherited following Mendelian principles. The lack of a comprehensive, relevant, manually compiled and genome-ready dataset of red cell antigens limited the widespread application of genomic technologies to characterise and interpret the blood group complement of an individual from genomic datasets.

MATERIALS AND METHODS

A range of public datasets was used to systematically annotate the variation compendium for its functionality and allele frequencies across global populations. Details on phenotype or relevant clinical importance were collated from reported literature evidence.

RESULTS

We have compiled the Blood Group Associated Genomic Variant Resource (BGvar), a manually curated online resource comprising all known human blood group related allelic variants including a total of 1700 International Society of Blood Transfusion approved alleles and 1706 alleles predicted and curated from literature reports. This repository includes 1682 single nucleotide variations (SNVs), 310 Insertions, Deletions (InDels) and Duplications (Copy Number Variations) and about 1360 combination mutations corresponding to 43 human blood group systems and 2 transcription factors. This compendium also encompasses gene fusion and rearrangement events occurring in human blood group genes.

CONCLUSION

To the best of our knowledge, BGvar is a comprehensive and a user-friendly resource with most relevant collation of blood group alleles in humans. BGvar is accessible online at URL: http://clingen.igib.res.in/bgvar/.

Paper based analytical devices for blood grouping: a comprehensive review

The clinical importance of blood group (BG) antigens is related to their ability to induce immune antibodies that can cause hemolysis. Yet, ABO and D (Rh) are still considered to be the key antigens for healthy blood transfusion and secondary antigens are the next priority. Serological typing is the most widely used typing method. Rapid and accurate blood grouping plays an important role in some clinical conditions, rather than conventional techniques. Hence, developing a simple and economical model for rapid blood grouping would facilitate these tests. In recent decades, paper-based microfluidics such as μPADs has gained much interest in wide application areas such as point-of-care diagnostic. In this study, we evaluated μPADs that are performed for blood grouping and its recent progress. A comprehensive literature search was performed using databases including PUBMED, SCOPUS, Web of Science and Google Scholar. Keywords were blood grouping or typing, paper analytical device, rapid test, etc. After investigation of search results, 16 papers from 2010 to 2020 were included. Further information in detail was classified in Table 1. Generally, two principles for blood typing μPADs are introduced. The lateral chromatographic flow method and the vertical flow-through method that detects BG in a visual-based manner. To detect results with acceptable clarity many factors and challenges like paper, blood sample, buffer, Ab and RBC interaction and also μPADs stability need to be considered, which are discussed. In conclusion, the simplicity, stability, cheapness, portability and biocompatibility of μPADs for blood grouping confirming its utility and also they have the capability to robust, universal blood-grouping platform. Table 1 Summary of blood grouping tests using paper-based analytical devices Antigens Type of diagnosis Validation method Sample No Accuracy Action time Paper type Stability Sample dilution Buffer Ref A, B, Rh Forward volunteers records 5 - - Whatman No. 4 - 1/2 PBS* (Khan et al. 2010) A, B, Rh Forward gel assay test and conventional slide test 100 100% 1 min Whatman No. 4 and Kleeenex paper towel 7 Days in 4 °C 1/1 NSS (Al-Tamimi et al. 2012) A, B, Rh Forward gel card assay 99 100% 20 Sec + Washing Kleeenex paper towel - 1/1 NSS (Li et al. 2012) A, B, Rh Forward - - - - Kleeenex paper towel - 45/100 PSS (Li et al. 2013) A, B, Rh Forward gel card assay 98 100% 1.5 min Kleeenex paper towel - 85/100 PBS (Guan et al. 2014b) C, E, c, e, K, Jka, Jkb, M, N, S, P1, and Lea Forward gel card assay 266 100% - Kleeenex paper towel - 1/1 NSS (Li et al. 2014b) A, B, Rh Forward and Reverse conventional slide test 96 ≈ 91% 10 min Whatman No. 1 21 Days in 4 °C 1/2 NSS (Noiphung et al. 2015) C, c, E, e, K, k, Fya, Fyb, Jka, Jkb, M, N, S and s, P1, Lea and Leb Forward - 478 - - Kleeenex paper towel - 1/1 NSS, PBS (Then et al. 2015) A, B Forward and Reverse conventional slide test 76 100% 5-8 min Whatman No. 4 38 Days in 4 °C 1/4, 1/1 NSS (Songjaroen and Laiwattanapaisal 2016) D, K Forward volunteers records 210 - 7.5 min Kleenex paper towel - 1/1 NSS (Yeow et al. 2016) A, B, c, e, D, C, E, M, N, S, s, P1, Jka, Jkb, Lea, Leb, Fya, and Fyb Forward and Reverse gel card assay 3550 ≈100% 30 s Fiber glass and cotton linter 180 Days in 25 °C 45/100, 1/1 PBS (Zhang et al. 2017) A, B Forward conventional slide test 598 100% 3 min Whatman No. 113 14 Day in 4 °C 1/1 NSS (Songjaroen et al. 2018) A, B, Rh Forward conventional slide test - - 30 Sec + Washing Unrefined sisal paper - 1/2 NSS (Casals-Terré et al. 2019) A, B, Rh Forward - - - - Whatman No.1 - 1/1 NSS (Ansari et al. 2020) ABO & Rh Forward and Reverse conventional slide test - 100% Unrefined Eucalyptus papers - 1/2 NSS, PBS (Casals-Terré et al. 2020) A, B, Rh Forward - - - 30 Sec + Washing Whatman No. 4 modified with chitosan  ≥ 100 days in 25 °C 1/1 NSS (Parween et al. 2020) ^*phosphate buffer saline, normal saline solution.

Frequency of Rh and K antigens in blood donors in Riyadh

Objectives

Investigate the prevalence of Rh and the K antigens and their phenotypes in the red blood cells of blood donors in Riyadh, Saudi Arabia.

Methods

This is a retrospective study. The five principal Rh antigens (D, C, c, E, e) and the Kell antigen from the Kell blood group were tested in 4,675 random samples collected from four blood bank centers in Riyadh. Data were collected for seven weeks (from January 4, 2019 to February 28, 2019). Antigens were tested using the TANGO Optimo system.

Results

We found that approximately 86% of the donors had the D antigen, 66% had C, 78% had c, 26% had E, 97% had e and 14% had K. The most common Rh phenotypes were R1r (31%) and R1R1 (22%).

Conclusion

The differences in the results between the study population and other populations, such as Caucasian, Indian and African populations indicate the importance of establishing a population-specific database.

Maternal red blood cell alloimmunisation Working Party, literature review. RH blood group system: Rare specificities

This report is part of a series reporting the GRADE review performed by the 2018-2020 French Working Party on maternal red blood cell alloimmunisation. This report focusses on the clinical significance in obstetrics, as published in the scientific literature, of the rare RH antibodies, variants and antigens (i.e. excluding conventional RH1 trough RH8 antigens, RH12, RH22 and RH27, which are discussed in other reports of this series). Extremely severe or severe haemolytic disease of the fetus and the newborn (HDFN), leading to death or requiring transfusions, have been reported for: anti-RH1 (-D) associated with DVI, DBT and DIVb phenotypes, RHD*12.04 (DOL4), RHD*03.03 (DIIIc), RHD*D-CE(2-5)-D, RHD*01EL.31 (RHD*148+1T), anti-RH9 (-C^X), anti-RH11 (-E^W), anti-RH17 (-Hr⁰), anti-RH18 (-Hr), anti-RH19 (-hr^S), anti-RH23 (-D^W), anti-RH29 ("total" Rh), anti-RH30 (-Go^a), anti-RH32, anti-RH34 (-Hr^B), anti-RH36 (-Be^a), anti-RH40 (-Tar), anti-RH46 (-Sec), anti-RH48 (-JAL), anti-RH54 (DAK), and antibodies to high prevalence antigens such as those associated with RHCE*02.08.02 (RHCE*C^W-RHD(6-10)), RHCE*03N.01 (RHCE*cEMI). HDFN of moderate, mild or undetailed severity have been reported for: anti-RH1 associated with DHar, DIIIa and DIVa phenotypes, RHD*01EL.08 (RHD*486+1A),RHD*01EL.44 (RHD*D-CE(4-9)-D),RHD*25 (DNB), anti-RH20 (-VS), anti-RH31 (-hr^B), anti-RH37 (-Evans), ani-RH42, anti-RH49 (-STEM), anti-RH51 (-MAR), anti-RH55 (-LOCR), anti-RH58 (-CELO). Positive direct antiglobulin test in the newborn but no clinically significant HDFN has been reported for anti-RH1 (-D) associated with RHD*10.05 (DAU5), RHD*12.02 (DOL2). Because so many specificities are associated with severe HDFN in the RH system, all RH antibodies should be considered as potentially able to cause HDFN, even if none has been reported yet.

A Review of the Literature Organized Into a New Database: RHeference

Hundreds of articles containing heterogeneous data describe D variants or add to the knowledge of known alleles. Data can be difficult to find despite existing online blood group resources and genetic and literature databases. We have developed a modern, elaborate database for D variants, thanks to an extensive literature search with meticulous curation of 387 peer-reviewed articles and 80 abstracts from major conferences and other sources. RHeference contains entries for 710 RHD alleles, 11 RHCE alleles, 30 phenotype descriptions (preventing data loss from historical sources), 35 partly characterized alleles, 3 haplotypes, and 16 miscellaneous entries. The entries include molecular, phenotypic, serological, alloimmunization, haplotype, geographical, and other data, detailed for each source. The main characteristics are summarized for each entry. The sources for all information are included and easily accessible through doi and PMID links. Overall, the database contains more than 10,000 individual pieces of data. We have set up the database architecture based on our previous expertise on database setup and biocuration for other topics, using modern technologies such as the Django framework, BioPython, Bootstrap, and Jquery. This architecture allows an easy access to data and enables simple and complex queries: combining multiple mutations, keywords, or any of the characteristics included in the database. RHeference provides a complement to existing resources and will continue to grow as our knowledge expands and new articles are published. The database url is http://www.rheference.org/.

ABO system combination with Rh, Kell and MN group in Georgian blood donors

There are numerous scientific data about the study of the prevalence of blood group antigens in the different donor population. Several studies showed that the profile of major blood group antigens is not similar in blood donors from different local areas.

RESEARCH OBJECTIVE

Our scientific goal was to study of the prevalence blood group antigens in the Georgian blood donor population. In the current study, we analyzed the 48 phenotypically combinations based on four major (ABO, Rh, Kell, and MN) blood groups.

RESEARCH METHODS

The blood of 1009 donors has been studied on RBC antigens. The sample were collected from the diagnostic laboratory of Medina Ltd Health Centre of Batumi. Blood typing of the sample has been carried out on the basis of the immunogenetics laboratory of Batumi Shota Rustaveli State University. The universal monoclone antibodies was used for identify minor blood group antigens. We used as forward as reverse grouping methods. For identification erythrocytes, blood group antigens also were used ID cards, such as ABO/D + Reverse Grouping.

RESULT

12 phenotypic combinations have been identified in each O, A, B, AB group of ABO system. Out of 48 theoretically possible phenotypic combinations, we can actually find 1,9 times less phenotypes and the real amount is 25 phenotypes. The remaining 23 phenotypic combinations have not been observed in the studied donors. These are: 1. O, Rh^-K⁺ MM; 2. O, Rh^-K^- MN; 3. O, Rh^-K^- NN; 4. A, Rh^-K⁺ MN; 5. A, Rh^-K⁺ MM; 6. A, Rh^-K⁺ NN; 7. A, Rh^-K^- MM; 8. A, Rh^-K^- NN; 9. B, Rh⁺K⁺ NN; 10. B, Rh^-K⁺ MN; 11. B, Rh^-K⁺ MM; 12. B, Rh^-K⁺ NN; 13. B, Rh^-K^- MN; 14. B, Rh^-K^- MM; 15. B, Rh^-K^- NN; 16. AB, Rh⁺K⁺ MN; 17. AB, Rh⁺K⁺ NN; 18. AB, Rh⁺K^- NN; 19. AB, Rh⁺K^- MM; 20. AB, Rh^-K⁺ MN; 21. AB, Rh^-K⁺ MM; 22. AB, Rh^-K⁺ NN; 23. B, Rh^-K^- NN. The value of χ² in the case is equal to 3221,16. The P-Value is < .00001. The result is significant at P < .05. Out of 1009 studied donors 349 are carriers of phenotypic group A (II), while 19 donors carry AB (IV) group specification. This means that 36.23% of the studied donors have A antigen on the surface of erythrocyte membrane. The majority of them A1 subgroup.

CONCLUSION

As our research showed there is a quit high polymorphism of blood group phenotype combinations in Georgian blood donors in the example of one clinic. This kind of data is very important for the clinics' rational preparation of whole blood or blood components.

An open-source python library for detection of known and novel Kell, Duffy and Kidd variants from exome sequencing

BACKGROUND AND OBJECTIVES

Next generation sequencing (NGS) has promising applications in transfusion medicine. Exome sequencing (ES) is increasingly used in the clinical setting, and blood group interpretation is an additional value that could be extracted from existing data sets. We provide the first release of an open-source software tailored for this purpose and describe its validation with three blood group systems.

MATERIALS AND METHODS

The DTM-Tools algorithm was designed and used to analyse 1018 ES NGS files from the ClinSeq® cohort. Predictions were correlated with serology for 5 antigens in a subset of 108 blood samples. Discrepancies were investigated with alternative phenotyping and genotyping methods, including a long-read NGS platform.

RESULTS

Of 116 genomic variants queried, those corresponding to 18 known KEL, FY and JK alleles were identified in this cohort. 596 additional exonic variants were identified KEL, ACKR1 and SLC14A1, including 58 predicted frameshifts. Software predictions were validated by serology in 108 participants; one case in the FY blood group and three cases in the JK blood group were discrepant. Investigation revealed that these discrepancies resulted from (1) clerical error, (2) serologic failure to detect weak antigenic expression and (3) a frameshift variant absent in blood group databases.

CONCLUSION

DTM-Tools can be employed for rapid Kell, Duffy and Kidd blood group antigen prediction from existing ES data sets; for discrepancies detected in the validation data set, software predictions proved accurate. DTM-Tools is open-source and in continuous development.

Rapidly freeze-dried human red blood cells for pre-transfusion alloantibody testing reagents

Prior to transfusion of red blood cells (RBCs), recipients must be tested for the presence of alloantibodies to avoid immune complications. Liquid-preserved reagent RBCs with known blood group antigen phenotypes are used for testing. However, these reagents have practical constraints, including limited shelf-life and require constant refrigeration. To address these issues, we explore the effects of rapid freeze-drying conditions with trehalose cryoprotectant (0.1-1 M concentrations) on human RBCs and storage of freeze-dried RBCs (FDRBCs) at room temperature (RT) for up to 12 months. We report that rapid freeze-drying of RBCs for 2.5 hr with 0.5 M trehalose achieves recoverable cells with near-normal morphological shape, although size-reduced. The FDRBCs are metabolically active and functional in antibody-agglutination tests by the column agglutination test (CAT) for ABO and Rhesus-D blood group antigens. Expression of the Duffy blood group protein (CD234) decreases by 50% after freeze-drying RBCs. The initial recovery rate is ≤25%; however, 43% of these FDRBCs are still recoverable after RT storage for 12 months. In this proof-of-principle study, we show that rapid freeze-drying can stabilize RBCs. Further refinements to improve the recovery rate and preservation of antigenic epitopes will make FDRBCs a practical alternative source of reagent RBCs for pre-transfusion alloantibody identification.

Acute hemolytic transfusion reaction caused by anti-Yta

Many patients with anti-Yt^a receive multiple transfusions of Yt(a+) red blood cells (RBCs) with no ill effects. However, anti-Yt^a has been implicated in hemolytic transfusion reactions. Antibody identification typically determines specificity of antibodies and their clinical significance to justify blood requirements for antigen-negative blood when clinically significant antibodies are involved. Occasionally, specificity of antibody is of variable significance. Variability in clinical significance is a characteristic of anti-Yt^a that may affect the clinical management of such patients. This case reports the outcome of an incompatible transfusion in an 83-year-old female patient with anti-Yt^a, -D, -C, -Le^ab, and -HI who was admitted to the hospital for a severe urinary tract hemorrhage and fever. The patient was transfused with 1 crossmatch-incompatible group A, Yt(a+), D-, C-, E-, S- RBC unit in an emergency medical event. During that time, the patient exhibited chills, shivering, and tachycardia. Decreases in hemoglobin and hematocrit were noted. Laboratory parameters for hemolysis, such as total bilirubin, direct bilirubin, and lactate dehydrogenase, were increased. Based on clinical and laboratory evaluation, it was concluded that the patient had an acute hemolytic transfusion reaction caused by anti-Yt^a. The patient was successfully treated with antipyretics, antihistamines, and corticosteroids. Urinary tract hemorrhaging was stopped. Anemia was additionally improved with parenteral iron supplementation, and further transfusion was not required. Immunohematology 2021;37:13-17. Many patients with anti-Yt^a receive multiple transfusions of Yt(a+) red blood cells (RBCs) with no ill effects. However, anti-Yt^a has been implicated in hemolytic transfusion reactions. Antibody identification typically determines specificity of antibodies and their clinical significance to justify blood requirements for antigen-negative blood when clinically significant antibodies are involved. Occasionally, specificity of antibody is of variable significance. Variability in clinical significance is a characteristic of anti-Yt^a that may affect the clinical management of such patients. This case reports the outcome of an incompatible transfusion in an 83-year-old female patient with anti-Yt^a, -D, -C, -Le^ab, and -HI who was admitted to the hospital for a severe urinary tract hemorrhage and fever. The patient was transfused with 1 crossmatch-incompatible group A, Yt(a+), D–, C–, E–, S– RBC unit in an emergency medical event. During that time, the patient exhibited chills, shivering, and tachycardia. Decreases in hemoglobin and hematocrit were noted. Laboratory parameters for hemolysis, such as total bilirubin, direct bilirubin, and lactate dehydrogenase, were increased. Based on clinical and laboratory evaluation, it was concluded that the patient had an acute hemolytic transfusion reaction caused by anti-Yt^a. The patient was successfully treated with antipyretics, antihistamines, and corticosteroids. Urinary tract hemorrhaging was stopped. Anemia was additionally improved with parenteral iron supplementation, and further transfusion was not required. Immunohematology 2021;37:13–17.

Pharmacogenomics with red cells: a model to study protein variants of drug transporter genes

The PharmacoScan pharmacogenomics platform screens for variation in genes that affect drug absorption, distribution, metabolism, elimination, immune adverse reactions and targets. Among the 1,191 genes tested on the platform, 12 genes are expressed in the red cell membrane: ABCC1, ABCC4, ABCC5, ABCG2, CFTR, SLC16A1, SLC19A1, SLC29A1, ATP7A, CYP4F3, EPHX1 and FLOT1. These genes represent 5 ATP-binding cassette proteins, 3 solute carrier proteins, 1 ATP transport protein and 3 genes associated with drug metabolism and adverse drug reactions. Only ABCG2 and SLC29A1 encode blood group systems, JR and AUG, respectively. We propose red cells as an ex vivo model system to study the effect of heritable variants in genes encoding the transport proteins on the pharmacokinetics of drugs. Altered pharmacodynamics in red cells could also cause adverse reactions, such as haemolysis, hitherto unexplained by other mechanisms.

Monocyte monolayer assay in pre-transfusion testing: A magic key in transfusing patients with recurrent bad cross-match due to alloimmunization

BACKGROUND

The monocyte monolayer assay (MMA) is an in-vitro assay that can predict the outcome of blood transfusion of antigen positive units when serologically compatible blood is not available.

MATERIALS AND METHODS

Fifty-four patients testing positive by the antibody screening test using gel agglutination were further examined by the alloantibody identification panel to determine alloantibody specificity. After determining and categorizing the antibodies, patients' samples were examined using the MMA to determine the clinical significance of the detected alloantibodies. We also tested 2 seeding methods (24-well cell culture plates versus 8-well chamber-slides) and 3 visualization/staining techniques (unstained phase contrast, Leishman and Giemsa staining).

RESULTS

35 out of the 54 cases (64.8%) had a monocyte index of >5% which is predictive of occurrence of hemolytic reaction after transfusion; 23 cases with antibodies known to be clinically significant [anti-C, anti-E, anti-c, anti-K, anti-Fy(a), anti Fy(b), anti-JK(b)], 2 with Anti-M specificity, 7 cases with autoantibodies and 3 cases with multiple antibodies. On the other hand, 19 out of the 54 (35.2%) cases included in the study showed a monocyte index of <5% which is predictive of absence of hemolytic reaction after transfusion. The 8-well chamber-slides were better than the 24-well culture plates, as the latter showed a lot of un-phagocytosed RBCs in the background. Also, Leishman staining was better than Giemsa staining with better and clearer differentiation between the RBCs, monocytes and phagocytic vacuoles.

CONCLUSION

MMA can be used as a surrogate cross-match test for the selection of blood units in cases where antigen-negative blood units are not available.

SCAR: The high-prevalence antigen 013.008 in the Scianna blood group system

BACKGROUND

The Scianna (SC) blood group system comprises seven antigens. They reside on the erythroblast membrane-associated glycoprotein (ERMAP). The ERMAP and RHCE genes are juxtaposed to each other on chromosome 1. We report a novel SC antigen.

STUDY DESIGN AND METHODS

Blood samples came from a patient and his two sisters in Saudi Arabia. To investigate the antibody specificity we used the column agglutination technique and soluble recombinant ERMAP protein. The significance of anti-SCAR was evaluated by the transfusion history and a monocyte monolayer assay. We determined the genomic sequence of ERMAP and RHCE genes.

RESULTS

The patient's serum showed an antibody of titer 8 against a high-prevalence antigen. The soluble recombinant ERMAP protein inhibited the antibody. The propositus genotyped homozygous for an ERMAP:c.424C>G variant, for which his sisters were heterozygous. The c.424C>G variant occurred in the SC*01 allele in one haplotype with the RHCE*03 (RHCE*cE) allele. No signs of hemolysis occurred following an incompatible blood transfusion. The monocyte monolayer assay was negative.

CONCLUSIONS

We characterized a high-prevalence antigen, with the proposed name "SCAR," which is the eighth antigen of the Scianna blood group system (proposed designation 013.008). Individuals homozygous for ERMAP:p.(Gln142Glu) protein variant can produce anti-SCAR. Although we did not observe any sign of hemolysis at this time, the anti-SCAR prompted a change of the treatment regimen. A review of the known reports indicated that all SC alloantibodies of sufficient titer should be considered capable of causing hemolysis.

Silent red blood cell autoantibodies: Are they naturally occurring or an effect of tolerance loss for a subsequent autoimmune process?

Unexpected anti-red blood cell (RBC) alloantibodies are routinely investigated in immunohematology and blood banking since their existence in pregnant women may induce haemolytic disease of the foetus and newborn, and their presence in donors may induce haemolytic transfusion reactions or hyperacute rejection in solid organ transplantation. Unexpected anti-RBC alloantibodies may target antigens of the most blood types excluding the expected antibodies targeting the ABO antigens. Their incidence in humans was originally linked to alloimmunization events such as blood transfusions, transplants, or pregnancies. But later, many findings revealed their existence in pathogenic processes such as malignancies, infections, and autoimmune diseases; and usually (but not always) associated to autoimmune haemolytic anaemia (AIHA). Nevertheless, unexpected anti-RBC autoantibodies are also occasionally found in healthy individuals in the absence of AIHA and with no history of alloimmunization or the associated pathologic processes. Hence, they are generally known as non-clinically significant, are excluded for typification and called "silent red blood cell autoantibodies (SRBCAA)". This review highlights evidence related to genetic predisposition, molecular mimicry, immune dysregulation, and immune tolerance loss surrounding the existence of anti-RBC antibodies, describing the presence of SRBCAA as possible early witnesses of the development of autoimmune diseases.

Lack of the multidrug transporter MRP4/ABCC4 defines the PEL-negative blood group and impairs platelet aggregation

The rare PEL-negative phenotype is one of the last blood groups with an unknown genetic basis. By combining whole-exome sequencing and comparative global proteomic investigations, we found a large deletion in the ABCC4/MRP4 gene encoding an ATP-binding cassette (ABC) transporter in PEL-negative individuals. The loss of PEL expression on ABCC4-CRISPR-Cas9 K562 cells and its overexpression in ABCC4-transfected cells provided evidence that ABCC4 is the gene underlying the PEL blood group antigen. Although ABCC4 is an important cyclic nucleotide exporter, red blood cells from ABCC4null/PEL-negative individuals exhibited a normal guanosine 3',5'-cyclic monophosphate level, suggesting a compensatory mechanism by other erythroid ABC transporters. Interestingly, PEL-negative individuals showed an impaired platelet aggregation, confirming a role for ABCC4 in platelet function. Finally, we showed that loss-of-function mutations in the ABCC4 gene, associated with leukemia outcome, altered the expression of the PEL antigen. In addition to ABCC4 genotyping, PEL phenotyping could open a new way toward drug dose adjustment for leukemia treatment.

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.

Is ABO blood group a risk or prognostic factor for patients with endometrioid endometrial cancer? A retrospective analysis in Germany

BACKGROUND

A relationship is known to exist between gastric and pancreatic cancers and ABO antigens, caused by various immune modulations related to the ABO blood group of the patient. A similar relationship with regard to gynaecological cancers remains controversial.

MATERIALS AND METHODS

Patients who underwent surgery for endometrioid endometrial cancer in International Federation of Gynaecology and Obstetrics (FIGO) stage I, II, III or IV from 2006 to 2018 were identified. The research explored the existence of a relationship between the patients' blood group or Rhesus factor and the incidence of endometrial cancer, grade (G1, G2, G3), FIGO stage, nodal status, recurrence, menopausal status, parity, and body mass index. Statistical methods such as the chi-square test, analysis of variance and the Scheffé post-hoc test were used.

RESULTS

Two hundred and two patients with endometrioid endometrial cancer were included: 96 had blood group A, 19 blood group B, 75 blood group 0, and 12 had blood group AB. This distribution corresponds to the general blood group distribution in Germany. The vast majority of the dependent variables, such as grade, FIGO stage, nodal status or recurrence were not significantly associated with ABO blood group or Rhesus factor status. The relative frequencies of G1 and G3 endometrial cancers with respect to blood group were similar. Menopausal status, parity, and body mass index were not related to more advanced FIGO stages at initial diagnosis or to ABO blood group.

DISCUSSION

Blood group screening would probably not be helpful in the diagnosis of endometrioid endometrial carcinomas in early stages compared to the current gold standard. Furthermore, a specific blood group does not increase either the risk of recurrence or the risk of a dedifferentiated type of endometrial carcinoma.

Characterization of sheep erythrocyte glycosphingolipids recognized by human anti-Forssman antibodies

The FORS histo-blood group system is the most recently discovered carbohydrate-based human blood group system. FORS is a rare blood group system, and most individuals have naturally occurring anti-FORS1 antibodies in plasma. Screening for anti-FORS1 antibodies is often done by hemagglutination assays using FORS1-expressing sheep erythrocytes, since FORS1-positive human erythrocytes are most often not available. Here, we have characterized the non-acid glycosphingolipids from sheep erythrocytes and isolated subfractions, with mass spectrometry, binding of antibodies and lectins, and by enzymatic hydrolysis. This demonstrated the presence of Forssman and Galili pentaosylceramides, and a Galili heptaosylceramide. Two complex glycosphingolipids recognized by human anti-FORS1 antibodies were characterized as a Forssman neolacto hybrid hexaosylceramide (GalNAcα3GalNAcβ3Galβ4GlcNAcβ3Galβ4Glcβ1Cer) and a Forssman Galili hybrid heptaosylceramide (GalNAcα3GalNAcβ3Galα3Galβ4GlcNAcβ3Galβ4Glcβ1Cer). These are novel glycosphingolipid structures, and to our knowledge, the first case of an elongated Galili antigen. Thus, the anti-Forssman antibodies in human serum bind not only to the classical Forssman pentaosylceramide (GalNAcα3GalNAcβ3Galα4Galβ4Glcβ1Cer), but also when the GalNAcα3GalNAcβ3 sequence is presented on a neolacto core chain and even on a Galili carbohydrate sequence.

Do Blood Group Antigens and the Red Cell Membrane Influence Human Immunodeficiency Virus Infection?

The expression of blood group antigens varies across human populations and geographical regions due to natural selection and the influence of environment factors and disease. The red cell membrane is host to numerous surface antigens which are able to influence susceptibility to disease, by acting as receptors for pathogens, or by influencing the immune response. Investigations have shown that Human Immunodeficiency Virus (HIV) can bind and gain entry into erythrocytes, and therefore it is hypothesized that blood groups could play a role in this process. The ABO blood group has been well studied. However, its role in HIV susceptibility remains controversial, while other blood group antigens, and the secretor status of individuals, have been implicated. The Duffy antigen is a chemokine receptor that is important in the inflammatory response. Those who lack this antigen, and type as Duffy null, could therefore be susceptible to HIV infection, especially if associated with neutropenia. Other antigens including those in the Rh, Lutheran and OK blood group systems have all been shown to interact with HIV. More recently, experiments show that cells which overexpress the P^k antigen appear to be protected against infection. These reports all demonstrate that red cell antigens interact and influence HIV infection. However, as the red cell membrane is complex and the pathogenesis of HIV multi-factorial, the role of blood group antigens cannot be studied in isolation.