[Molecular biological identification of a case with A223B subtype].

OBJECTIVE: To study the molecular basis for a proband with A subtype B of the ABO blood group and explore the influence of amino acid variant on the activity of glycosyltransferase (GT). METHODS: A proband who had presented at the First Affiliated Hospital of Zhengzhou University on July 2, 2020 was selected as the study subject. Serological identification of the ABO blood groups of the proband and her family members were performed by gel card and test tube methods. The ABO gene of the proband was identified by PCR-sequence specific primers (PCR-SSP) and DNA sequencing. A 3D molecular homologous model was constructed to predict the impact of the variant on the stability of α-(1→3)-D-N-acetylgalactosamine transferase (GTA). RESULTS: The red blood cells of the proband, her mother and two younger brothers showed weak agglutination with anti-A and strong agglutination with anti-B. The sera showed 1~2+ agglutination with Ac and no agglutination with Bc. Based on the serological characteristics, the proband was identified as AwB subtype. Pedigree analysis suggested that the variant was inherited from her mother. The blood group of the proband was identified as A223B type by PCR-SSP. ABO gene sequencing analysis showed that the proband has harbored heterozygous variants of c.297A>G, c.467C>T, c.526C>G, c.657C>T, c.703G>A, c.796C>A, c.803G>C, c.930G>A and c.1055insA. Based on the results of clone sequencing, it was speculated that the genotype was ABO*A223/ABO*B.01. There were c.467C>T and c.1055insA variants compared with ABO*A1.01, and c.1055insA variant compared with ABO*A1.02. Homologous modeling showed that the C-terminal of A223 GT was significantly prolonged, and the local amino acids and hydrogen bond network have changed. CONCLUSION: Above results revealed the molecular genetics mechanism of A223B subtype. The c.1055insA variant carried by the proband may affect the enzymatic activity of GTA and ultimately lead to weakening of A antigen.

Rh Blood Group Antigens and Alloimmunization Risk of Pregnant Women in South Western, Nigeria.

BACKGROUND: Rh blood group antigens are the second most important blood group antigens in clinical transfusion due to their immunogenicity and prevalence. Childbirth, miscarriage, and other obstetrics events are risk factors for alloimmunization in women which increases the likelihood of haemolytic blood transfusion reaction and hemolytic disease of the fetal/newborn (HDNF/B). Even though there are several data on the RhD status of our populations. However, there is a dearth of data on pregnant women's C, E, c, and e status, their alloimmunization risk, and rates in Nigeria. OBJECTIVES: This study aims to provide information on the distribution of the Rh major antigens and risk factors for alloimmunization in pregnant women in southwestern Nigeria. MATERIALS AND METHODS: This was a descriptive cross-sectional study of 133 pregnant women attending routine ante-natal clinics. Questionnaires were administered to collect biodata and obstetrics history. ABO blood grouping and Rh phenotyping were carried out on their blood samples using RAPID LABS Monoclonal Rhesus Typing Reagent. RESULTS AND DISCUSSION: Rh blood group antigen c was present in 100% of the women, followed by e (98.5%) and D (95.5%). C and E are the least prevalent antigens and probably the ones to which antibodies may be formed. The commonest Rh phenotype was Dce. Of all the pregnant women, alloimmunization was present in 0.8%. Of those who were RhD negative, alloimmunization was present in 16.7%. Pregnant women are more likely to be alloimmunized against C and E antigens than c and e antigens due to their low and high frequencies respectively.

CONTEXTE: Les antigènes du groupe sanguin Rh sont les seconds plus importants en transfusion clinique en raison de leur immunogénicité et de leur prévalence. L'accouchement, la fausse couche et d'autres événements obstétriques sont des facteurs de risque d'alloimmunisation chez les femmes, augmentant ainsi la probabilité de réactions hémolytiques lors de transfusions sanguines et de maladies hémolytiques du fœtus/nouveau-né (HDNF/B). Bien qu'il existe plusieurs données sur le statut RhD de nos populations, il y a un manque de données sur le statut des antigènes C, E, c et e chez les femmes enceintes, leur risque d'alloimmunisation et les taux associés au Nigéria. OBJECTIFS: Cette étude vise à fournir des informations sur la distribution des principaux antigènes Rh et les facteurs de risque d'alloimmunisation chez les femmes enceintes dans le sud-ouest du Nigéria. MÉTHODOLOGIE: Il s'agit d'une étude descriptive transversale de 133 femmes enceintes fréquentant les cliniques prénatales de routine. Des questionnaires ont été administrés pour collecter des données biodémographiques et des antécédents obstétriques. La détermination des groupes sanguins ABO et le phénotypage Rh ont été réalisés sur leurs échantillons de sang à l'aide du réactif de typage Rh monoclonal RAPID LABS. RÉSULTATS ET DISCUSSION: L'antigène c du groupe sanguin Rh était présent chez 100 % des femmes, suivi de e (98,5 %) et D (95,5 %). Les antigènes C et E sont les moins prévalents et probablement ceux contre lesquels des anticorps peuvent être formés. Le phénotype Rh le plus courant était Dce. Parmi toutes les femmes enceintes, l'alloimmunisation était présente chez 0,8 %. Parmi celles qui étaient RhD négatives, 'alloimmunisation était présente chez 16,7 %. Les femmes enceintes sont plus susceptibles de développer une alloimmunisation contre les antigènes C et E que contre les antigènes c et e en raison de leurs fréquences respectives faibles et élevées. MOTS-CLÉS: Antigènes du groupe sanguin Rh, Phénotype, Alloanticorps érythrocytaires, Femmes enceintes.

Frequency of Duffy, Kidd, Lewis, and Rh Blood Group Antigens and Phenotypes Among Donors in the Al-Ahsa Region, Saudi Arabia.

BACKGROUND: In Al-Ahsa, Saudi Arabia, the high consanguinity rates contribute to the prevalence of inherited hemoglobinopathies such as sickle cell disease and thalassemia, which frequently require blood transfusions. These transfusions carry the risk of alloimmunization, necessitating a precise blood component matching to mitigate health risks. Local antigen frequency data is vital for optimizing transfusion practices and enhancing the safety of these medical procedures for the Al-Ahsa population. METHODS: This study investigated the distribution of Duffy, Kidd, Lewis, and Rh blood group antigens in 1,549 individuals from the region; comparing the frequencies with global data. RESULTS: Serological analyses revealed a high prevalence of the Fy(a+b-) and Jk(a+b+) phenotypes in the Duffy and Kidd blood groups, respectively, with Jk(a-b-) being notably scarce. The Lewis blood group exhibited a significant presence of Le(a-b+) and Le(a+b-) phenotypes, whereas Le(a+b+) was less common. In the Rh system, the D antigen was most prevalent, with other antigens following in descending order of frequency. CONCLUSIONS: The study underscores the regional variation in antigen frequencies, emphasizing the need for local blood banks to adapt their screening and matching practices to mitigate the risk of alloimmunization and enhance transfusion safety. These findings are pivotal for refining transfusion strategies and understanding the immunohematology landscape in Al-Ahsa.

Application of RhD Blood Group to Simulate Antibody Identification Test in Immunohematology Education.

BACKGROUND: Immunohematology skill education is an important part of the transfusion medicine professional training. We tried to solve the difficulty of obtaining suitable and sufficient positive samples in the immunohematology education. METHODS: Different identification panels and panel cells were created by RhD-positive red blood cells (RBCs) and RhD-negative RBCs, according to the underlying antibodies. Diluted anti-D reagent was used as simulated plasma for identification. RESULTS: The antibody identification of single antibody with dose-effect and two antibodies present at the same time were successfully simulated. CONCLUSIONS: It is a practical and cheap method for antibody identification training to use RhD blood group, especially when positive samples are short.

Maximum surgical blood ordering schedule for elective surgical procedures in Omdurman teaching hospital, Sudan.

BACKGROUND: The need for blood during a surgical procedure is greater than what blood banks are able to provide. There is an excessive amount of blood being ordered for elective surgeries, surpassing the actual requirements. Only 30% of the cross matched blood is actually used in these surgeries. The accuracy of estimating the transfusion needs before a surgical procedure can be determined by looking at the cross match to transfusion ratio and the transfusion index. "These indicators play a crucial role in developing the maximum surgical blood ordering schedule; in this study, these indicators were tested." AIM OF STUDY: Is to determine the efficiency of blood ordering and transfusion practices for patients undergoing elective surgeries. METHODS: This study is a prospective cross-sectional hospital-based study done at Omdurman Teaching Hospital-Sudan. Conducted for the duration of 6 months period from July to December 2019.The study participants were patients who underwent elective surgical procedures in general surgery and Urology departments as total coverage sample over a period of study duration. Ethical clearance obtained from ethical committee of Sudan Medical Specialization Board. RESULTS: Two hundreds seven patients included in this study, the amount of blood units requested were 443-unit, cross matching for 98.6% (n 437) of units were done. Only 100 unit were Transfused (22,8%). The calculated CT ratio was 4.4, transfusion index was 1.6 and transfusion probability was 29.9%. CONCLUSION: Transfusion probability and transfusion index of the present study were optimal but comparatively higher than the standard guidelines as most of the cross matched blood was not utilized.

When and why is red blood cell genotyping applicable in transfusion medicine: a systematic review of the literature.

This review aims to provide a better understanding of when and why red blood cell (RBC) genotyping is applicable in transfusion medicine. Articles published within the last 8 years in peer-reviewed journals were reviewed in a systematic manner. RBC genotyping has many applications in transfusion medicine including predicting a patient's antigen profile when serologic methods cannot be used, such as in a recently transfused patient, in the presence of autoantibody, or when serologic reagents are not available. RBC genotyping is used in prenatal care to determine zygosity and guide the administration of Rh immune globulin in pregnant women to prevent hemolytic disease of the fetus and newborn. In donor testing, RBC genotyping is used for resolving ABO/D discrepancies for better donor retention or for identifying donors negative for high-prevalence antigens to increase blood availability and compatibility for patients requiring rare blood. RBC genotyping is helpful to immunohematology reference laboratory staff performing complex antibody workups and is recommended for determining the antigen profiles of patients and prospective donors for accurate matching for C, E, and K in multiply transfused patients. Such testing is also used to determine patients or donors with variant alleles in the Rh blood group system. Information from this testing aides in complex antibody identification as well as sourcing rare allele-matched RBC units. While RBC genotyping is useful in transfusion medicine, there are limitations to its implementation in transfusion services, including test availability, turn-around time, and cost.

Serologic profiling of D variants in donor routine: unveiling the impact on false-negative results and alloimmunization.

The high number of D variants can lead to the unnecessary use of Rh immune globulin, overuse of D- RBC units, and anti-D allommunization. D variant prevalence varies among ethnic groups, and knowledge of the main variants present in a specific population, their behavior in serologic tests, and their impact on clinical practice is crucial to define the best serologic tests for routine use. The present study aimed to explore the serologic profile of D variants and to determine which variants are most associated with false-negative D typing results and alloimmunization. Donor samples were selected in two study periods. During the first period, D typing was performed on a semi-automated instrument in microplates, and weak D tests were conducted in tube or gel tests. In the second period, D typing was carried out using an automated instrument with microplates, and weak D tests were performed in solid phase. Samples from patients typed as D+ with anti-D were also selected. All samples were characterized by molecular testing. A total of 37 RHD variants were identified. Discrepancies and atypical reactivity without anti-D formation were observed in 83.4 percent of the samples, discrepant D typing results between donations were seen in 12.3 percent, and D+ patients with anti-D comprised 4.3 percent. DAR1.2 was the most prevalent variant. Weak D type 38 was responsible for 75 percent of discrepant samples, followed by weak D type 11, predominantly detected by solid phase. Among the D variants related to alloimmunization, DIVa was the most prevalent, which was not recognized by serologic testing; the same was true for DIIIc. The results highlight the importance of selecting tests for donor screening capable of detecting weak D types 38 and 11, especially in populations where these variants are more prevalent. In pre-transfusion testing, it is crucial that D typing reagents demonstrate weak reactivity with DAR variants; having a serologic strategy to recognize DIVa and DIIIc is also valuable.

A patient with anti-f in India identified by extensive immunohematologic workup.

Anti-f is produced by exposure to the compound antigen ce (f) on red blood cells (RBCs), expressed when both c and e are present on the same protein (cis position). Although anti-f was discovered in 1953, there are few cases reported worldwide because the presence of anti-f is often masked by anti-c or anti-e and is not generally found as a single antibody. In the present case, anti-f was identified by using three-cell screening and 11-cell identification panels. The identification of anti-f was further supported by additional testing, including (1) Rh antigen typing; (2) antibody identification panels (enzyme-treated panel [ficin] and an in-house-constructed Rh panel); (3) look-back and phenotyping of donor RBC units, which were responsible for alloimmunization; and (4) molecular testing of the patient's RBCs.

[The Identification Idea of Antibodies Against Ku and Other High-Frequency Antigens].

OBJECTIVE: This study was aimed to provide ideas for identifying the antibodies to high-frequency antigens by analyzing a female case of high-frequency antigen antibody (anti-Ku) using serological and sequencing method. METHODS: The methods for identification of blood group, erythrocyte antigen, screening and identification of antibody were used to detect the blood type and antibody in the proband. The proband's serum and reagent screening cells treated with Sulfhydryl reagent were applied to judge the type and characteristics of this antibodies when reacted with the regaent screening cells or proband's serum respectively. Gene sequencing was used to determine the genotype of the proband's blood group. RESULTS: The proband's red blood cells were determined as O type RhD positive, whose serum showed strong positive reaction to antibody-screening cells and antibody identification cells with the same intensity in saline and IAT medium, however, the self-cells showed negative effect. The Direct Antihuman Globulin of proband's red blood cells also showed weak positive reaction, and the other blood types were CcEe, Jk(a+b-), P1-, Le(a-b -), Lu (a-b +), K-, k-, Kp(a-b-). Serum of the proband treated with 2-ME still react with three groups of screening cells in IAT medium. The reaction intensity of proband's serum was also unchanged with the cells modified with papain and bromelain, but showed negative effect when the cells were treated with sulfhydryl agents including DTT and 2-ME. Gene sequencing revealed that the KEL genotype of the patient was KEL*02N.24 . This patient had a rare K0 phenotype. CONCLUSION: The rare Kell-null blood group (also known as K0) were identified by serological and molecular tests in the proband who produced both IgG and IgM type of antibody to high-frequency antigen (anti-Ku). These two methods are of great significance in the identification of this rare blood group as well as the antibody to high frequency antigen.

[Distribution Characteristics of Rh Phenotype and Feasibility of Compatible Blood Transfusion in Pregnant and Postpartum Women].

OBJECTIVE: To analyze the distribution characteristics of Rh phenotype in pregnant and postpartum women in Chongqing area, and to explore the clinical significance of Rh phenotype in pregnant and postpartum women and the feasibility of Rh phenotype compatible blood transfusion. METHODS: The ABO blood group and Rh phenotype of 65 161 pregnant and postpartum women were detected by microcolumn gel method, and 48 122 males in the same period were taken as controls. The data were analyzed by Chi-square test. RESULTS: There were 112 870 cases (99.64%) of RhD+ in 113 283 samples. In RhD+ cases, CCDee (48.39%) and CcDEe (32.88%) were the main phenotypes. The first case of D-- phenotype in Chongqing area was detected. 413 cases (0.36%) of RhD- were detected, with ccdee (52.78%) and Ccdee (33.41%) as the main phenotypes. Compared with RhD- group, RhD+ group showed statistically significant difference in Rh phenotype distribution (P < 0.01). Among 65 161 maternal samples, the positive rate of 5 antigens of Rh blood group from high to low was D > e > C > c > E, and there was no significant difference compared with male samples (P >0.05). There was no significant difference in the distribution of Rh phenotype between males and pregnant/postpartum women, as well as between pregnant/postpartum women with different ABO blood groups (P >0.05). In pregnant and postpartum women, there was no significant difference in distribution of Rh phenotype among the normal pregnancy population, the population with adverse pregnancy history, the population using human assisted reproductive technology (ART) and the population with infertility (P >0.05). There was no significant difference in the distribution of Rh phenotype between the 4 populations mentioned above and the inpatients in the local general Grade A hospitals and the blood donors (P >0.05). In RhD positive pregnant and postpartum women, the probability of finding compatible blood for CcDEe phenotype was 100%, the probability of finding compatible blood for CCDee, CcDee and CCDEe phenotypes was 45%-60%, the probability of finding compatible blood for ccDEE, ccDEe and CcDEE phenotypes was 5%-10%, and the probability of finding compatible blood for other phenotypes was lower than 0.5%. The supply of blood with CCDee and ccDEE phenotypes can meet the compatible transfusions requirements of 7 Rh phenotypes in more than 99% of patients. CONCLUSION: Rh phenotype detection should be carried out for pregnant and postpartum women, and it is feasible to carry out Rh phenotype-matched or compatible blood transfusion for pregnant and postpartum women who need blood transfusion.

The Variation of RhD Blood Group in Different Periods in a Patient with Systemic Lupus Erythematosus.

BACKGROUND: Autoimmune hemolytic anemia disease often produces a large number of various autoantibodies, and some autoantibodies may be related to Rh blood group. In rare cases, autoantibodies can specifically target Rh antigen, thus interfering with the identification of Rh blood group. METHODS: A case of systemic lupus erythematosus (SLE) with inconsistent RhD blood group identification results in different periods was reported and the reasons were analyzed. RESULTS: Some autoantibodies can completely block D antigen on red blood cells, resulting in no redundant D sites on red blood cells binding to reagent anti D. In addition, the immunity of the body is extremely low, and the expression of red blood cell blood group antigens in part of the body is inhibited, which will cause the weakening of the expression of Rh antigen in red blood cells. Therefore, when testing the RhD blood type of the patient, the reagent anti D does not agglutinate with the patient's red blood cells, and a false negative result of the initial screening appears. Through the RhD negative confirmation test, the patient's blood type is a serologically weak D phenotype. CONCLUSIONS: If the result of serological preliminary screening test is RhD negative or RhD variant, the recipient should be treated as RhD negative, and RhD negative red blood cells should be transfused during blood transfusion. Conditional laboratories can implement RHD genotyping, which is conducive to improving the precise blood transfusion management level of RhD negative blood recipients, saving rare blood resources and improving the treatment efficiency of patients.

Meeting the transfusion needs of a patient with anti-Ena requires an international effort.

This extraordinary case showcases the identification of a rare anti-Ena specificity that was assisted by DNA-based red blood cell antigen typing and collaboration between the hospital blood bank in the United States, the home blood center in Qatar, the blood center Immunohematology Reference Laboratory, as well as the American Rare Donor Program (ARDP) and the International Society for Blood Transfusion (ISBT) International Rare Donor Panel. Ena is a high-prevalence antigen, and blood samples from over 200 individuals of the extended family in Qatar were crossmatched against the patient's plasma with one compatible En(a-) individual identified. The ISBT International Rare Donor Panel identified an additional donor in Canada, resulting in a total of two En(a-) individuals available to donate blood for the patient.

How do transfusion services manage patients taking therapies such as anti-CD38 and anti-CD47 known to interfere with red blood cell compatibility testing?

BACKGROUND: Drugs such as daratumumab (Darzalex, anti-CD38) and Hu5F9-G4 (magrolimab, anti-CD47) may interfere with red blood cell compatibility testing as CD38 and CD47 are expressed on red blood cells. STUDY DESIGN AND METHODS: A survey of AABB member transfusion services was undertaken to understand their experiences of managing patients taking therapeutic monoclonal antibodies that are known to interfere with blood grouping and compatibility testing. RESULTS: The survey was distributed to the contact person at US-based AABB member transfusion services. The response rate was 27%. 172 of 240 (72%) indicated they had difficulties in performing compatibility testing in patients taking daratumumab and 66 of 91 (73%) reported difficulties in performing compatibility testing in patients taking magrolimab. Actions taken to provide compatible blood for these patients included referral of all samples to a reference center, blood group pheno/genotyping the patient in advance of starting the drug, treating reagent cells with 0.2 M dithiothreitol and using K-negative red cell units for patients taking daratumumab, and Gamma-clone (Immucor) anti-IgG for indirect antiglobulin testing for patients taking magrolimab. Lack of communication from clinical services about drug treatment was identified as a concern. CONCLUSION: The results of the survey demonstrate that transfusion services are having challenges with the transfusion management of patients taking therapeutic monoclonal antibodies, and further education is needed.

Estimating waiting time for compatible blood: A Negative Binomial approach.

OBJECTIVES: Screening blood units for compatibility constitutes a Bernoulli series. Estimating the number of units needed to be screened represents a classic waiting time problem that may be resolved using the Negative Binomial Distribution. The currently recommended method for estimating the number of units screened, n, to find a required number of compatible units, r, with a given probability, p, is n = r/p. This coincides with the mean of the Negative Binomial Distribution so that the actual number of units screened will often be underestimated by the current method. METHODS: The cumulative distribution function of the Negative Binomial Distribution provides the probability of success (compatibility), F(n;r,p), as a function of the number of trials performed (attempted crossmatches), n, the probability of success on each trial, p, and the number of successes (compatible units) required, r. Choosing a threshold cumulative probability sufficiently high, such as F ~ 0.9, for example, will provide confidence that the projected number of units screened will be underestimated less often (~10% of the time). RESULTS: With F ≥ 0.9, the estimated number of attempted crossmatches ranges from 1.3 to 2.3 times as many as the number calculated by the current method. As a rule of thumb approximately 1.6 times the current estimated number provides a similar estimate (n ~ 1.6∙r/p). CONCLUSIONS: Waiting time underestimation will be reduced significantly by using the Negative Binomial Distribution solution and should be accompanied by improved customer satisfaction.

Serology and molecular genetic analysis of two unrelated individuals with the same novel CisAB blood type.

OBJECTIVE: This study aims to report two unrelated individuals with the same novel CisAB blood type and confirm this rare blood type using a comprehensive approach that combines serological and molecular biology techniques. METHODS: Peripheral blood samples were collected from two patients and their family members. ABO blood typing and antibody detection were performed using conventional tube methods. Molecular biology techniques were employed to amplify and sequence the 6th and 7th exons of the ABO gene, with reference to gene mutation databases provided by NCBI and ISBT. RESULTS: The genotypes of the two unrelated individuals were identical and were confirmed as a new genotype through ISBT gene database comparison. Serological testing results showed different antigen reaction patterns, especially in terms of reverse typing. Gene sequencing identified a series of mutation points, and both unrelated individuals and one of their daughters had mutations at 297 A>G, 526 C>G, 657 C>T, 703 G>A, 803 G>C, and 930 G>A. According to the comprehensive results from The Blood Group Antigen Gene Mutation Database provided by NCBI, the genotype was determined as Bw37. However, based on the results from Names for ABO (ISBT 001) blood group alleles v1.1 171023, the sequencing results indicated a novel mutation combination not found in the ISBT database. Considering the serological reactions of all three individuals, the final determination was CisAB. CONCLUSIONS: This study confirmed the novel CisAB blood type in two individuals through the comprehensive application of serology and molecular biology techniques. The identified gene mutation points were not recorded in known databases, emphasizing the uniqueness of CisAB blood types. This research provides important insights into the genetic basis of ABO subtypes and the characteristics of CisAB blood types, and the relevant results have been submitted to the ISBT website for further research.

Frequency of red blood cell phenotypes from genotyped Australian blood donors.

BACKGROUND: Australian Red Cross Lifeblood (Lifeblood) performs human erythrocyte antigen (HEA) genotyping for a subset of repeat whole-blood donors through preferential selection which aims to maximise variation of results and possibility of identifying donors lacking high frequency red cell antigens. MATERIALS AND METHODS: The HEA Molecular Bead chip™ assay is used by Lifeblood for donor genotyping. A review of all donor HEA genotype data from March 2019 to May 2022 (3 years) was conducted. RESULTS: HEA genotyping was performed for 20,185donors. Due to selective genotyping of donors, a higher frequency of R1R1 predicted phenotype was identified. However, frequencies of other red cell phenotypes were relatively similar to previous reported in the Australian population. A small number of donors with rare red cell phenotypes was identified. CONCLUSION: Genotyping of blood donors provides an available pool of extended matched red blood cell products for matching to recipients. Additionally genotyping can improve the identification of donors with rare phenotypes. Whilst limitations exist, genotyping may reduce the need for labour intensive serotyping, improve blood inventory management, and may be useful in donor recruitment and retention.

[Feasibility Analysis of Establishing Combat Readiness Blood Bank Based on Low Titer Group O Whole Blood and Group A Plasma].

OBJECTIVE: To explore the feasibility of establishing combat readiness blood bank with low titer group O whole blood and group A plasma. METHODS: The Galileo automatic blood analyzer was used to detect the titers of IgM anti-A and anti-B antibodies in the samples of group O blood donors and IgM anti-B titer in the samples of group A blood donors. Group O blood donors with antibody titers below 128 were selected and included in the mobile blood bank for combat readiness, group A plasma with anti-B titer lower than 128 and group O whole blood with antibody titers below 128 were included in the combat readiness entity blood bank. RESULTS: A total of 1 452 group O blood donors were selected, and the anti-A/B antibody titers were detected. Both antibody titers were distributed below 512, and both peak values of sample distribution were at titer 4. The proportion of samples with titers>128 for both antibodies was relatively low. There was a significant positive correlation between the titers of the two antibodies (r =0.383), and the proportion of samples with IgM anti-A titer higher than IgM anti-B titer was relatively high. 1 335(91.94%) group O blood donors with IgM anti-A and anti-B antibody titers <128 could be included in the mobile blood bank. The anti-B titer of group A blood was detected in 512 cases and the results showed that as the antibody titer increased, the proportion of blood donors gradually decreased. 99.8% of group A blood donors had anti-B antibody titer less than 128, and only one case did not meet the inclusion criteria. CONCLUSION: The proportion of group O blood donors whose whole blood meet the low antibody titer standard is high, and almost all plasma of group A blood donors meet the low titer standard, which improves the blood supply rate in emergencies.

Study of the antigenic characteristics of red blood cells units and their sickle cell disease recipients and the G6PD activity of transfused red blood cells units.

INTRODUCTION: Transfusion has a central place in the treatment of patients with sickle cell disease (SCD). Matching blood groups of red blood cell (RBC) units with the blood groups of the patient is essential to prevent alloimmunization and delayed hemolytic transfusion reaction. African ancestry donors have the best phenocompatibility with patients of the same origin, however their RBCs may present characteristic that can alter quality of the unit such as glucose-6-phosphate dehydrogenase (G6PD) deficiency. The objective is to analyze transfusion protocol, immunization rate and mismatch situations of SCD recipients and to evaluate the frequency of G6PD deficiency in RBCs units from African ancestry donors. METHODS: Samples of units transfused to SCD patients were analyzed. Transfusion data were collected from institutional databases. The activity of G6PD was measured in the segment of the RBC units. RESULTS: A total of 98 segments of units transfused to 37 SCD recipients in 41 transfusions episodes was collected. Among patients, 35.1% (n = 13) had no antibodies; 10.8% (n = 4) had antibodies against Fya/Fyb, Jka/Jkb, M/N, S/s; 21.6% (n = 8) against RH/K antigens. In all cases, the protocols were in line with the recommendations. G6PD deficiency was observed in 9 units, that were all collected from Afro-Caribbean donors. CONCLUSION: The transfusion protocol is established to prevent immunological reactions due to disparities in blood group antigens between donors and SCD recipients. However, the units of African ancestry donors, which allowed the best compatibility, displayed a high rate of G6PD deficiency. The storage and recovery impact of this deficiency must be evaluated.

A machine-learning method for biobank-scale genetic prediction of blood group antigens.

A key element for successful blood transfusion is compatibility of the patient and donor red blood cell (RBC) antigens. Precise antigen matching reduces the risk for immunization and other adverse transfusion outcomes. RBC antigens are encoded by specific genes, which allows developing computational methods for determining antigens from genomic data. We describe here a classification method for determining RBC antigens from genotyping array data. Random forest models for 39 RBC antigens in 14 blood group systems and for human platelet antigen (HPA)-1 were trained and tested using genotype and RBC antigen and HPA-1 typing data available for 1,192 blood donors in the Finnish Blood Service Biobank. The algorithm and models were further evaluated using a validation cohort of 111,667 Danish blood donors. In the Finnish test data set, the median (interquartile range [IQR]) balanced accuracy for 39 models was 99.9 (98.9-100)%. We were able to replicate 34 out of 39 Finnish models in the Danish cohort and the median (IQR) balanced accuracy for classifications was 97.1 (90.1-99.4)%. When applying models trained with the Danish cohort, the median (IQR) balanced accuracy for the 40 Danish models in the Danish test data set was 99.3 (95.1-99.8)%. The RBC antigen and HPA-1 prediction models demonstrated high overall accuracies suitable for probabilistic determination of blood groups and HPA-1 at biobank-scale. Furthermore, population-specific training cohort increased the accuracies of the models. This stand-alone and freely available method is applicable for research and screening for antigen-negative blood donors.