Benefits of blood group genotyping in multi‐transfused patients from the south of Brazil

We evaluated the usefulness of blood group genotyping as a supplement to hemagglutination to determine the red blood cell (RBC) antigen profile of polytransfused patients with hematological diseases and renal failure. Seventy‐nine patients were selected. They all received more than three units of blood and eight (10%) had already clinical significant alloantibodies occurring alone or in combination against Rh, K, Fya, and Di antigens. DNA was prepared from blood samples and RHCE*E/e, KEL*01/KEL*02, FY*01/FY*02 and JK*01/JK*02 alleles were determined by using PCR‐RFLP. RHD*/RHD*Ψ and RHCE*C/c were tested using multiplex PCR. Discrepancies for Rh, Kell, Duffy, and Kidd systems were found between the phenotype and genotype‐derived phenotype in 16 of the 38 chronically transfused patients. The genotypes of these patients were confirmed by DNA array analysis (HEA Beadchip^?; Bioarray Solutions, Warren, NJ). Genotyping was very important for the determination of the true blood groups of the polytransfused patients, helped in the identification of suspected alloantibodies and in the selection of antigen‐negative RBCs for transfusion. J. Clin. Lab. Anal. 24:311–316, 2010. © 2010 Wiley‐Liss, Inc.     

Another example of a KEL1 variant red cell phenotype due to a threonine to serine change at position 193 of Kell glycoprotein

BACKGROUND: Healthy subjects whose red blood cells (RBCs) react variably with anti-KEL1, but strongly express other Kell blood group antigens, have been described and called KEL1 variant. A 53-year-old Caucasian blood donor was identified whose RBCs reacted with three monoclonal and two polyclonal anti-KEL1 and did not react with two monoclonal and one polyclonal anti-KEL1. The molecular basis of this phenotype was investigated.
STUDY DESIGN AND METHODS: Genomic white blood cell DNA was analyzed for KEL * 1/2 genotype by utilizing sequence-specific primers and polymerase chain reaction. In addition, the region of the KEL * 1/2 polymorphism at position 578 of KEL was analyzed by DNA sequencing.
RESULTS: Genotyping of the donor with the KEL1 variant phenotype revealed that he was KEL * 2 homozygous. Sequencing revealed one typical KEL * 2 allele and a KEL * 2 allele with an adenosine (A) to thymidine (T) substitution at position 577 that predicted a threonine to serine change at position 193.
CONCLUSION: It is not known if this phenotype is clinically relevant, but for at least some genotyping applications probes that identify this polymorphism should be used and anti-KEL1 should be tested for reactivity to this allele.     

A KEL gene encoding serine at position 193 of the Kell glycoprotein results in expression of KEL1 antigen

BACKGROUND: The KEL2/KEL1 (k/K) blood group polymorphism represents 578C>T in the KEL gene and Thr193Met in the Kell glycoprotein. Anti-KEL1 can cause severe hemolytic disease of the fetus and newborn. Molecular genotyping for KEL*1 is routinely used for assessing whether a fetus is at risk. Red blood cells (RBCs) from a KEL:1 blood donor (D1) were found to have abnormal KEL1 expression during evaluation of anti-KEL1 reagents. STUDY DESIGN AND METHODS: Kell genotyping methods, including KEL exon 6 direct sequencing, were applied. KEL cDNA from D1 was sequenced. Flow cytometry was used to assess KEL1 and KEL2 RBC expression. RESULTS: RBCs from the donor, her mother, and an unrelated donor gave weak or negative reactions with some anti-KEL1 reagents. Other Kell-system antigens appeared normal. The three individuals were homozygous for KEL C578 (KEL*2) but heterozygous for a 577A>T transversion, encoding Ser193. They appeared to be KEL*2 homozygotes by routine genotyping methods. Flow cytometry revealed weak KEL1 expression and normal KEL2, similar to that of KEL*2 homozygotes. CONCLUSION: Ser193 in the Kell glycoprotein appears to result in expression of abnormal KEL1, in addition to KEL2. The mutation is not detected by routine Kell genotyping methods and, because of unpredicted KEL1 expression, could lead to a misdiagnosis.     

Molecular basis of two novel high-prevalence antigens in the Kell blood group system, KALT and KTIM

BACKGROUND: The Kell blood group system consists of 25 antigens that result from single-nucleotide polymorphisms. Most polymorphic Kell antigens reside on the N-terminal domain of Kell before the zinc-binding catalytic motif, which is the major site for endothelin-3-converting enzyme activity. Kell antigens are important in transfusion medicine owing to their strong immunogenicity, and the corresponding antibodies are clinically significant. Two probands were studied whose serum samples contained antibodies to different high-prevalence Kell antigens. STUDY DESIGN AND METHODS: Standard hemagglutination methods were used for serologic testing of Proband 1 and Proband 2. DNA was prepared from both probands and family members. The 19 exons and the intron-exon regions of KEL from both probands were amplified by polymerase chain reaction, and the sequences were compared with that of common KEL. The identified substitutions were located on a three-dimensional model of Kell generated based on the crystal structure of neutral endopeptidase, a homolog of Kell. RESULTS: In Proband 1, a homozygous 1988G>A mutation (Arg623Lys) in Exon 17 was present. One sibling of Proband 1 was homozygous for 1988G>A. In Proband 2, a homozygous 1033G>A mutation (Asp305Asn) in Exon 8 was present. Three siblings of Proband 2 were heterozygous for 1033G>A. CONCLUSION: The identified KEL mutations of the two probands are novel and inherited. The antigen absent from the red blood cells (RBCs) of Probands 1 and 2 are named KALT and KTIM, respectively. KALT is unique in that it is the only Kell antigen sensitive to treatment of RBCs by trypsin.     

Serology and gene sequence analysis of the B(A) subtype of patients in Hunan

IntroductionB(A) is a relatively rare ABO subtype. The frequency of B(A) in European Caucasians is low, but is higher in China. B(A) is common in northern China, gradually decreasing from north to south. The frequency of B(A) has been researched in northern China, but not in southern China. This study aimed to investigate the serological characteristics and molecular mechanism of the B(A) subtype in Hunan.MethodsThe phenotypes of ABO blood group were analyzed by blood group serology for the patients in the Third Xiangya Hospital from 2016 to 2020; Exons 1–7 of the ABO gene were screened by PCR-SSP and sequencing.ResultsNine cases were suspected as belonging to the B(A) subtype by serological tests. The activity of D-galactosyltransferase in these patients' serum was significantly higher than that of group B plasma; meanwhile, there was no activity of Nacetylgalactosyltransferase. The ABO genotype was ABO*B.01/O.01.01 or ABO*B.01/O.01.02, and the gene sequencing results confirmed the phenotype as B(A), whose gene frequence was 1/26,000. Allele ABO*BA.02 (1/38,000) had the highest frequency, followed by ABO*BA.04 (1/77,000).ConclusionAmong the patients in Hunan, the most common allele encoding the B(A) phenotype was ABO*BA.02. The identification of the B(A) blood group required serological methods combined with genotyping.     

1例罕见的B(A)亚型的鉴定

B(A)亚型是一种罕见的ABO亚型,其分子机制为B等位基因在正常B基因序列的基础上发生单碱基突变,使其具有编码双功能活性酶的能力。B(A)亚型在血清学检测中除表现B抗原特异性外,还表现少量A抗原特异性,从而干扰血型鉴定及配血工作。B(A)型如误定为AB型,输入AB型红细胞可引起溶血性输血反应。国内已报道7个等位基因,其中B(A)02型发生率为0.78/10万。现将报道1例工作中遇到的B(A)O2型。     

Generation of transgenic mice with antithetical KEL1 and KEL2 human blood group antigens on red blood cells

BACKGROUND: KEL1, also known as “K,” is one of the most immunogenic red blood cell (RBC) antigens. KEL2, also known as “k,” differs from KEL1 by a single amino acid. Anti‐Kell system antibodies can lead to significant adverse clinical outcomes in humans, including hemolytic complications in alloimmunized transfusion recipients or in infants of alloimmunized mothers. To provide a platform for in‐depth immunologic studies of alloimmunization and subsequent sequelae, we generated transgenic mice expressing the human KEL1 or KEL2 antigens. STUDY DESIGN AND METHODS: Vectors were created in which cDNAs encoding either KEL1 or KEL2 were regulated by an erythroid specific β‐globin promoter and enhancer. Pronuclear microinjections were carried out into a C57BL6 background, and founder pups were identified by polymerase chain reaction and screened for expression by flow cytometry. RBC life span and antigen stability were assessed by dye labeling RBCs, transfusing into agammaglobulinemic (µMT) recipients, and tracking by flow cytometry. RESULTS: The expression of either KEL1 or KEL2 is RBC specific and first occurs on early RBC precursors. Both KEL1 and KEL2 RBCs have a normal circulatory life span and stable antigen expression. Expression of KEL1 or KEL2 does not result in altered levels of murine Kell, and resulting RBCs have normal hematologic variables. CONCLUSION: The KEL1 and KEL2 mice represent the first murine system of RBC immunity with antithetical antigens, allowing a more precise modeling of human RBC immunology in general and also a platform for development of novel therapeutics to prevent or minimize the dangers of RBC alloimmunization to the KEL1 and KEL2 antigens in particular.     

The HLA-DRB1*11 group-specific allele is a predictor for alloantibody production in the transfusion-dependent thalassemia patients

Background and ObjectivesRecently, researchers have shown an increased interest in thalassemia for detecting susceptible factors in alloimmunization development. Alloimmunization, especially against Rh and Kell blood, occurs in 30% of thalassemia dependent transfusion (TDT) patients. The aim of this study is to determine the role of HLA-DRB1*11 and HLA-DRB1*13 group-specific alleles in the production of Rh and Kell alloantibodies.Materials and Methods106 TDT patients were recruited for this study (54 responders and 52 non-responders). Responder patients developed Rh, Kell and/or specificities alloantibodies. HLA genotyping was done with Sequence-Specific Primers (SSP-PCR) and the results were compared between two groups.ResultsA significant association was found between anti-K (P=0.021, OR=2.546, 95%CI) and anti-E (P=0.049, OR=2.304, 95%CI) alloantibodies production with DRB1*11, respectively. Development of Anti-K and Anti-E alloantibodies were associated with DRB1*11 (P = 0.021, OR = 2.546, 95%CI) (P = 0.049, OR = 2.304, 95%CI), respectively. Further analysis showed that DRB1*11 is more frequent in multi responders (responder with both Rh and Kell alloantibodies) than mono-responders, 71% Versus 29%. There was not found any association between the DRB1*13 group-specific allele and the production of alloantibodies (P = 0.584, OR = 0.308, 95%CI).ConclusionsThe evidence from this study suggests that detecting the DRB1*11 group-specific allele before starting transfusion can be useful to identify susceptible patients, increase HSCT transplantation compatibility and blood transfusion management.     

Genotyping of blood groups in alloimmunized patients with β-thalassemia major by T-ARMS-PCR and multiplex-aso-pcr

IntroductionBeta-thalassemia major is a severe hemolytic anemia requiring life-long blood transfusion. Planned random donor blood transfusion is associated with alloimmunization against incompatible antigens. Determination of the minor blood group systems phenotype or genotype, and administration of the compatible blood components can significantly reduce the rate of alloimmunization.The present study aimed to determine the prevalence of alloimmunization, and genotype/phenotype characteristics of the minor blood groups systems in patients with β-thalassemia major.Material and methodsThis study was conducted on 1147 β-thalassemia major patients. Initially, antibody screening and antibody identification were performed. Then, phenotyping and genotyping for the Rh, Kell, Kidd, and Duffy blood groups were done in alloimmunized patients using monoclonal antibodies and Multiplex-Allele Specific Oligonucleotide-Polymerase Chain Reaction (Multiplex-ASO-PCR) and Tetra-primer amplification refractory mutation system–PCR (T-ARMS-PCR), respectively. Any phenotype/genotype discrepancy was assessed by direct sequencing.ResultsNinety-seven (8.5 %) out of 1147 patients had alloantibodies against the minor blood group antigens (44 males, 45.4 %, and 53 female, 54.6 %). The most common alloantibodies were against the RH (n: 47, 48.5 %), and the Kell (n: 23, 23.7 %) blood groups systems. Twenty-three (2.1 %) genotype/phenotype discrepancies out of 1067 tests, including 9 in the Rh (9.3 %), 8 in Duffy (34.8 %), and 6 in Kidd (26.1 %) blood groups were detected. No discrepancy was found in the Kell blood group system. Direct sequencing revealed that the results of molecular methods were correct.ConclusionMultiplex-ASO-PCR and T-ARMS-PCR molecular methods are fast, reliable and cost-benefit molecular methods for the minor blood group genotyping in multi-transfused β-thalassemia major patients.     

Distribution of Diego blood group alleles and genotypes in the Chinese Korean population and sequence-based identification

ObjectiveTo investigate Diego blood group alleles in the Chinese Korean population. The Diego blood group system plays an important role in transfusion medicine, but the distribution of the blood group in many Chinese ethnic populations remains unclear.MethodsSequence Specific Primer Polymerase Chain Reaction (SSP-PCR) was used for Diego genotyping and sequence-based typing PCR (PCR-SBT) was used to verify single nucleotide polymorphisms in the coding region of SLC4A1 starting from exon 19. Nine hundred and ten samples from the Chinese Korean population were investigated.ResultsThe frequency of the DI*01 and DI*02 alleles in the Chinese Korean population was 0.0516 and 0.9484, respectively. The most predominant genotype was DI*02/DI*02, with a frequency of 90.22 % (821/910). The frequency of DI*01/DI*02 was 9.23 % (84/910) and that of DI*01 /DI*01 was 0.55 % (5/910). The genotype distributions of the Diego blood group conformed to the Hardy-Weinberg equilibrium (P > 0.05).ConclusionThe data obtained from this study will be helpful for the creation of a donor database to provide antigen-negative blood to patients with allo-antibodies. Genotyping can be used as a substitute for the serological technique when antisera are unavailable and is suitable for screening a large number of donors for rare-blood-group databases.     

Genotyping analysis of the MNS blood group system of thalassemia patients with alloantibodies in Iran

BackgroundSerological methods are unreliable for accurate determination of blood group antigens in multi-transfused thalassemia patients. The MNS blood group system has five high-frequency antigens. Many studies demonstrated that some antibodies including anti-S, anti-s, and anti-U may cause acute and delayed transfusion reactions and hemolytic disease of the fetus and newborn. This study aimed to determine the genotype of the MNS blood group in thalassemia patients with alloantibodies by molecular methods.Material and methodsIn this study, 104 blood samples from thalassemia patients were collected. The blood group phenotype for M, N, S and s antigens was determined by the tube hemagglutination method. MNS blood group genotyping was performed using PCR-SSP and DNA Sequencing methods.ResultsAll patients were genotyped with a total of 6 pairs of primers. Discrepancies between genotype and phenotype were observed in 22 patients with S/s alleles and 2 patients with M/N alleles, however, there was full accordance between the results of SSP-PCR and DNA sequencing. The frequency of MNS blood group alleles was determined as follows: 25 % MNSs, 23 % MNss, 21 % MMSs, 9% MMSS, 9% MMss, 8% NNss, 2%MNSS, and NNSS, NNSs, MM genotypes at 1% each.ConclusionIn conclusion, molecular genotyping is more reliable than serological methods in multiple transfusion patients and can lead to a more compatible blood unit for transfusion in these patients.     

Prognostic Value Evaluation of HLA-DRB1*07:01, *10, *12, *13:01 Alleles for Alloimmunization in Transfusion-Dependent Thalassemia

BackgroundTransfusion is a lifesaving treatment for lots of patients. However, in chronic blood recipients such as thalassemia patients, there are high concerns about alloantibody production that affects the quality of their life. Therefore, research on risk factors of alloimmunization has been started and followed. This study aimed at the determination of correlation probability between some HLADRB1 alleles and alloimmunization in Iranian thalassemia patients.Materials and methodsThe present study was conducted on 60 alloimmunized and 60 non-alloimmunized transfusion-dependent thalassemia patients. Antibody screening and identification tests were carried out using the tube method, and HLA-DRB1 genotyping was done using a single specific primer-polymerase chain reaction (PCRSSP).ResultsThe results of antibody screening showed that the most prevalent alloantibodies were Anti-K (46.7 %), and followed by Anti-E (32.5 %), Anti-C (15.8 %), Anti-D (13.3 %), Anti-e (8 %), and Anti-c (5.8 %), respectively. DRB1*07:01 was detected more in non-responder patients (28.3 %). However, data analysis showed that there is no significant relationship between DRB1*07:01, *10, *13:01 frequency among responder and non-responder groups (p = 0·195, 0.648, 0.402, respectively). There was not any significant correlation between HLA-DRB1*10 and *13:01 allele and alloimmunization. There was a significant association between HLA-DRB1*12 and alloimmunization (p < 0·05, OR = 2.071, CI: 1.716–2.501).ConclusionThe findings of this study represented that there is a significant relationship between HLADRB1*12 and Kell and E alloantibodies. Although more developed studies on other HLA alleles are demanded, these findings can be valuable in determining important alloimmunization risk factors to better management of transfusion complications.     

Pancytopenia in a newborn due to maternal piperacillin and human leukocyte antigen antibodies

BackgroundPiperacillin antibody-induced immune hemolytic anemia is not rare in adults, and there have been reports of anti-HLA antibody-induced newborn platelet transfusion refractoriness. However, there has been no report of piperacillin-accompanied anti-HLA antibody-induced newborn pancytopenia.Case ReportWe herein present the case of a newborn with pancytopenia from a mother who carried anti-HLA-B55, anti-HLA-DR11, and piperacillin antibodies. The newborn HLA genotypes were HLA*B55:02 and HLA*DRB1*11:01. IgG antibodies can be transferred to the newborn via the placenta and induce the destruction of the platelet and white blood cells, which carry the corresponding antigens. Piperacillin antibodies coupling with newborn red blood cells (RBCs) led to the destruction of the RBCs and hemolytic anemia.ResultsThe direct anti-globulin test was positive for RBCs in the newborn, and piperacillin antibodies were positive in both the newborn and his mother. Anti-HLA antibodies were positive in the maternal serum, whereas homologous antigens were positive in the newborn. The direct anti-globulin test of platelet was weekly positive in the newborn.ConclusionPiperacillin and anti-HLA antibodies can pass through the placenta, induce incompatible blood cell destruction, and cause a series of clinical syndromes in newborns.     

Blood group genotyping in multi-transfused patients

BackgroundIn chronically transfused patients, the classical hemagglutination assays may be inaccurate in defining the RBC phenotypes of the patients due to previous transfusions.DesignDNA samples from 39 multi-transfused patients including thalassemia and sickle cell disease were used for red blood cell genotyping. The Rh-Type and KKD-Type (BAGene, BAG Healthcare) were used to determine the polymorphisms associated with antigen expression for RHD, RHCE and Kell, Kidd, Duffy blood group systems, respectively. Results were compared with previously determined phenotyping results for RhD, RhCcEe and Kell by hemagglutination method.ResultsNineteen out of the 37(51%) patients had discrepancies between genotyping and phenotyping results in a total of 25 alleles. In 12 patients, the discrepancies had the potential of alloimmunization.ConclusionBlood group genotyping has vital importance in transfusion management of chronically transfused patients especially if the patients were not phenotyped before starting the initial transfusions.     

Discrepancies between red cell phenotyping and genotyping in daily immunohematology laboratory practice

False-positive and false-negative reactions exist for serological and molecular antigen typing methods. If the predicted phenotype is inconsistent with the patient`s known antibodies or serological phenotype, the discrepancy must be investigated. False-negative and false-positive results are clinically problematic in blood donors and patients. In this study, we investigated discrepant results between serology and molecular testing in patients and blood donors that occurred in daily molecular laboratory practice over a two year-period. SCD patients represented a large percentage of our cases of discrepancies but we also observed a high prevalence of discrepancies between phenotypes and genotypes in blood donors. The main reasons that led to discrepancies were recent transfusions and limitations of phenotyping. Discrepancies classified as false positive phenotype/true negative genotype and false negative phenotype/true positive genotype occurred mainly in patients with recent transfusions and individuals with RH variants while those classified as true negative phenotype/false positive genotype involved null phenotypes due to silent genes. Despite the limitations of molecular methods currently employed, we found more false-negative and false-positive phenotypes than genotypes demonstrating that genotyping is more efficient to define the blood types, especially in transfusion dependent patients.     

Genetic and functional analyses describe a novel 730delG mutation in the KEL gene causing K0 phenotype in a Taiwanese blood donor

Aims/Objectives: The purpose of this study was to explore the molecular basis of the K₀ phenotype of a Taiwanese blood donor found to have anti‐Ku alloantibodies. Background: With respect to Kell blood group antigens, almost all Taiwanese have the (K−, k+) phenotype. Materials and Methods: Alloantibody identification and KEL antigen typing were performed. Enzymatic function assays were carried out to detect the Kell glycoprotein on RBCs. The KEL genes were sequenced to detect genetic variation. To determine the origin of this novel allele, family studies were conducted. Results: The alloantibody was identified as anti‐Ku. The donor was typed K₀. The KEL gene‐sequencing data revealed that this K₀ donor is a compound heterozygote with two different null alleles. He bears a novel 730delG mutation in one allele. Family studies suggested that the donor inherited the 730delG mutation from his father. The endothelin‐converting activity assay indicated that his RBCs had no functional Kell glycoprotein. Other family members who had only one null allele with the 730delG mutation had the phenotype (K−, k+). Conclusion: For blood transfusion safety, it is important to establish an effective screening algorithm to identify rare phenotypes, such as the K₀ phenotype, and to establish a database of rare blood groups.     

B(A)血型分子机制研究及其家系分析

目的 研究罕见B(A)血型的血清学特性和分子机制,为B(A)血型的临床输血提供理论基础.方法 利用单克隆抗体检测1例先证者、家系成员及献血者红细胞ABO血型抗原,用标准A、B、O红细胞检测其血清中的ABO抗体.采用盐水法、凝聚胺法和抗球蛋白法进行先证者与献血者交叉配合试验.采用PCR技术扩增ABO基因的第6、7外显子序列,对先证者、家系成员、献血者标本的ABO基因外显子6、7和侧翼内含子序列进行测序分析,并对先证者标本进行单倍体序列分析.结果 先证者及其2位家系成员红细胞上有A、B抗原,同时血清中存在抗A_1抗体,血清学表型为A_2B.直接测序分析发现先证者标本第6、7外显子存在261G/del、297A/G、526C/G、657C/T、700C/G、703A/G、796A/C、803G/C、930A/G杂合,可推断为B(A)_(02)/O_(01)基因型杂合子;家系中其母亲基因型为B(A)_(02)/B_(101),外祖母为B(A)_(02)/O_(01).先证者单倍体序列分析得到2个等位基因B(A)_(02)和O_(01);与B_(101)序列相比,B(A)_(02)位第700位C>G,导致1个氨基酸改变:第234位脯氨酸变成丙氨酸.既往血清学特性为A_2B的2个献血者,1个基因型为B(A)_(02)/O_(01),另1个基因型是A_(208)/B_(101).B(A)血型先证者与这2名献血者进行交叉配血试验均相合,临床输注后无不良反应.结论 α-1,3-半乳糖基转移酶等位基因(B等位基因)700C>G突变可导致形成B(A)血型,其血清学特性显示为A_2B表型.B(A)血型临床输血相配合的供者可选择A_2B表型的献血者.     

中华骨髓库造血干细胞捐献志愿者HLA基因分型中模棱两可结果解决方案的探讨

目的 探讨中华骨髓库造血干细胞捐献志愿者HLA基因分型中模棱两可结果的解决方案。方法 采用聚合酶链式反应(PCR)-测序分型技术(SBT)对20621名中华骨髓库供者的HLA-A、B、DRB1基因进行高分辨分型，并对其中的模棱两可分型结果进行精确分型。根据精确分型后的HLA等位基因频率计算模棱两可结果中真基因型的相...     

Red blood cell alloimmunization in transfusion-dependent Egyptian patients with thalassemia in a limited donor exposure program

BACKGROUND: Thalassemia is considered the most common hemoglobinopathy in Egypt and is one of its major health problems. Lifelong red blood cell (RBC) transfusion remains the main treatment for severe forms; however, RBC alloimmunization results as a complication of regular transfusions due to repeated exposure to foreign antigens. The objective was to compare the frequency of alloantibodies in a group of patients in a limited donor exposure program (LDEP) with those receiving RBCs from multiple donors in Egyptian transfusion‐dependent patients with thalassemia. STUDY DESIGN AND METHODS: A total of 235 regularly transfused patients with thalassemia were studied, 36 of which were on LDEP. All patients were investigated for the presence of RBC autoantibodies and alloantibodies, followed by antibody identification for positive patients. RESULTS: Forty‐six (19.5%) patients developed RBC alloantibodies. The most common clinically significant alloantibodies were directed against antigens in the Kell and Rh systems. Development of alloantibodies was associated with older age, higher transfusion frequency, and splenectomy. A trend toward lower alloimmunization was elicited in the LDEP group, where 8.3% (3/36) patients were alloimmunized compared to 21.6% (43/199) in the non‐LDEP one (p = 0.057). CONCLUSIONS: Examination of donor RBCs for presence of Kell and Rh(E) antigens before transfusion can help decrease RBC alloimmunization. Further larger studies are required to assess the frequency of alloantibody production in patients on LDEP.