International Society of Blood Transfusion Committee on Terminology for Red Cell Surface Antigens: Cape Town report

Approach to Pregnancy Affected by Kell Alloimmunization

Hemolytic disease of the fetus and newborn (HDFN) is the development of anemia, hyperbilirubinemia, and finally hydrops fetalis in the fetus when antibodies to antigens on the surface of erythrocytes are transferred from the placenta to the fetus. The most common cause is D-HDFN. K (KEL1) from the Kell blood group system is the most potent immunogenic antigen after D among all blood group antigens. K-HDFN occurs in 0.1-0.3% of pregnant women. It accounts for 10% of cases of antibody-mediated severe fetal anemia. We present a successful management of Kell alloimmunization in a pregnant woman who had 3 times pregnancy loss with hydrops fetalis due to K-HDFN and who was proven to have K-HDFN in the postnatal period in her last pregnancy.

Association between Rhesus Blood Groups and Malaria Infection: A Systematic Review and Meta-Analysis

In the literature, there was inconsistency in the risk of malaria between individuals with Rhesus blood group positive (Rh+) and negative (Rh−). The systematic review aimed to investigate the risk of malaria among participants with different Rh blood types. All observational studies that reported the occurrence of Plasmodium infection and investigation of the Rh blood group were searched in five databases (Scopus, EMBASE, MEDLINE, PubMed, and Ovid). Strengthening the Reporting of Observational Studies in Epidemiology was used to assess the reporting quality in the included studies. A random-effects model was used to calculate the pooled log OR and 95% confidence intervals (CIs). Database searches yielded a total of 879 articles, of which 36 were eligible for inclusion in the systematic review. The majority of the included studies (44.4%) revealed that Rh+ individuals had a lower proportion of malaria than Rh− individuals; however, the remaining studies revealed a higher or no difference in the proportion of malaria between Rh+ and Rh− individuals. Overall, with moderate heterogeneity, the pooled results showed no difference in malaria risk between patients with Rh+ and Rh− (p = 0.85, pooled log OR: 0.02, 95% CI: −0.20–0.25, I2: 65.1%, 32 studies). The current study found no link between the Rh blood group and malaria, even though there was a moderate amount of heterogeneity. Further studies using prospective designs and a definitive method for Plasmodium identification are needed to investigate the risk of Plasmodium infection in Rh+ individuals and increase the reliability and quality of these studies.

Detection of Homologous Blood Transfusion in Sport Doping by Flow Cytofluorimetry: State of the Art and New Approaches to Reduce the Risk of False-Negative Results

This article presents the results of a study aimed to give new suggestions and strategies for improving the implementation of the flow cytofluorimetry-based method for the detection of homologous blood transfusions in doping control. The method is based on the recognition of the phenotypic mismatch between minority blood group antigens possessed by the donor and the recipient. Two strategies have been followed to reduce the risk of false-negative results: (i) the monitoring of a broader range of erythrocytes surface antigens; and (ii) the application of different surface erythrocyte staining protocols, tailored on the different antigens and the type of antigenic mismatch that had to be detected (whether it is the donor or the recipient who expresses or not the antigen to be detected). Special attention has also been focused on the time factor, to avoid prolonged sample storage, since hemolysis may have a significant impact on the reliability and quality of the results. Our experimental evidence suggests that the risk of false-negative results can be minimized by (i) the expansion of the antigen panel, with the inclusion of four additional targets; (ii) a more accurate selection of the gating area of the red blood cells; (iii) the choice of a better fluorochrome (alexa fluor 488) to be conjugated to the secondary antibody; and (iv) the implementation of different staining protocols depending on the nature of the double population to be detected (donor expressing vs. recipient non-expressing and vice versa). The combination of the above approaches allowed a significant reduction of false-negative results, assessed on samples simulating a homologous blood transfusion between two compatible subjects.

Molecular analysis of the GYPB gene to infer S, s, and U phenotypes in an admixed population of Minas Gerais, Brazil

Objective

To implement genotyping for S, s and U antigens of the MNS blood group system at the Fundação Hemominas and to evaluate the occurrence of GYPB gene polymorphisms associated with the U- and U+var phenotypes and deletion of the GYPB gene for the first time in an admixed population of Minas Gerais, Brazil. The S, s and U antigens can cause transfusion reactions and perinatal hemolytic disease. Genotyping is a useful tool in immunohematology, especially when phenotyping cannot be performed.

Methods

Ninety-six samples from blood donors and patients with sickle cell disease previously phenotyped for the S, s and U antigens were selected. Allele-specific primer polymerase chain reaction (ASP-PCR) and polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP) assays were employed to identify the GYPB*S and GYPB*s alleles and the GYPB(P2) and GYPB(NY) variants, as well as deletion of the GYPB gene.

Results

The results of allele-specific genotyping (GYPB*S and GYPB*s) were totally in agreement with the phenotyping of S+ (n = 56), s+ (n = 60) and s- (n = 35) samples. However, the GYPB*S allele, in association with the GYPB(P2) variant, was detected in 17.5% of the S- samples (n = 40), which shows the importance of assessing this variant in the Brazilian population. Of the S-s- samples (n = 10), 60% had the deletion of the GYPB gene and 40% were homozygous or hemizygous for the GYPB(P2) variant.

Conclusion

Genotyping was an effective strategy to infer the S, s, and U phenotypes in the admixed population from Minas Gerais (Brazil) and may contribute to transfusion safety.

DARC alleles and Duffy phenotypes in African Americans

BACKGROUND

The DARC (Duffy blood group, chemokine receptor) gene encodes for a transmembrane glycoprotein that functions as a chemokine transporter, is a receptor for Plasmodium vivax and P. knowlesi, and expresses the Duffy blood group antigens (Fy). The Fy(a-b-) phenotype found in people of African descent is typically associated with a -67t>c mutation in the 5'-untranslated region (UTR), which prevents red blood cells being invaded by P. vivax and P. knowlesi. The aim of this study was to establish DARC allele frequencies in an African American blood donor cohort, determine a phylogenetic tree for DARC, and compare human and Neandertal DARC genes.

STUDY DESIGN AND METHODS

The DARC nucleotide sequence of 54 African American blood donors was determined from genomic DNA. Heterozygous substitutions were resolved by sequencing of haplotype-specific amplifications. A phylogenetic tree for DARC was established using the neighbor-joining method with Pan troglodytes as root.

RESULTS

A total of 108 haplotypes of the DARC gene could be unambiguously determined from nucleotide position -300 in the 5' UTR to +300 in the 3' UTR. Eleven different alleles were found, including the clinically relevant FY*A, FY*B, FY*B-67C, FY*B298A, and FY*X alleles. All phenotype predictions based on genotypes matched the serologically determined phenotypes exactly: 52% Fy(a-b-), 28% Fy(a-b+), and 20% Fy(a+b-).

CONCLUSIONS

The nucleotide sequencing approach using one amplicon is a practical genotyping method for DARC and allows the determination of haplotypes even in heterozygous constellations. We developed a phylogenetic tree for DARC alleles and postulated a distinct FY*B allele as ancestral for the extant DARC alleles in humans.

Association between Knops blood group polymorphisms and susceptibility to malaria in an endemic area of the Brazilian Amazon

Complement receptor 1 (CR1) gene polymorphisms that are associated with Knops blood group antigens may influence the binding of Plasmodium parasites to erythrocytes, thereby affecting susceptibility to malaria. The aim of this study was to evaluate the genotype and allele and haplotype frequencies of single-nucleotide polymorphisms (SNPs) of Knops blood group antigens and examine their association with susceptibility to malaria in an endemic area of Brazil. One hundred and twenty-six individuals from the Brazilian Amazon were studied. The CR1-genomic fragment was amplified by PCR and six SNPs and haplotypes were identified after DNA sequence analysis. Allele and haplotype frequencies revealed that the Kn(b) allele and H8 haplotype were possibly associated with susceptibility to Plasmodium falciparum. The odds ratios were reasonably high, suggesting a potentially important association between two Knops blood antigens (Kn(b) and KAM(+)) that confer susceptibility to P. falciparum in individuals from the Brazilian Amazon.

KEL*02 alleles with alterations in and around exon 8 in individuals with apparent KEL:1,-2 phenotypes

BACKGROUND AND OBJECTIVES

Antibodies to antigens in the Kell blood group system, especially anti-KEL1, are involved in both haemolytic disease of the newborn and foetus and haemolytic transfusion reactions. Correct typing results are important and discrepancies between serologic and genetic typing must be resolved. Here, we describe the investigation of three healthy individuals who were initially phenotyped as KEL:1,-2.

MATERIALS AND METHODS

Antigen typing was performed by standard serological techniques and by flow cytometric analysis. The KEL*01/02 polymorphism was tested by an allele-discrimination TaqMan assay as well as by PCR with allele-specific primers and PCR-RFLP. DNA sequencing of the KEL coding region was also performed.

RESULTS

Two KEL*02N alleles with mutated splice sites around exon 8 were identified: intron 7 -1g>c (novel) and intron 8 +1g>t (previously reported in one case of K(0)). In the third sample, a missense mutation in exon 8, 787G>A (novel) predicting Gly263Arg, was detected on a KEL*02 allele and associated with dramatically weakened KEL2 antigen expression.

CONCLUSION

Resolution of discrepant phenotype/genotype results identified silencing mutations in or around exon 8. A combination of molecular and serologic methods has the potential to improve the quality of test results and was required to ensure both the accurate KEL2 antigen status and KEL*01 zygosity of these individuals.

Blood groups and malaria: fresh insights into pathogenesis and identification of targets for intervention

PURPOSE OF REVIEW

This review summarizes recent advances in our understanding of the interaction between malaria parasites and blood group antigens and discusses how the knowledge gleaned can be used to target the development of new antimalarial treatments and vaccines.

RECENT FINDINGS

Studies of the interaction between Plasmodium vivax and the Duffy antigen provide the clearest example of the potential for basic research on blood groups and malaria to be translated into a vaccine that could have a major impact on global health. Progress is also being made in understanding the effects of other blood group antigens on malaria. After years of controversy, the effect of ABO blood groups on falciparum malaria has been clarified, with the non-O blood groups emerging as significant risk factors for life-threatening malaria, through the mechanism of enhanced rosette formation. The Knops blood group system may also influence malaria susceptibility, although conflicting results from different countries mean that further research is required. Unanswered questions remain about the interactions between malaria parasites and other blood group antigens, including the Gerbich, MNS and Rhesus systems.

SUMMARY

The interplay between malaria parasites and blood group antigens remains a fascinating subject with potential to contribute to the development of new interventions to reduce the global burden of malaria.

Novel single-nucleotide change in GYP*A in a person who made an alloantibody to a new high-prevalence MNS antigen called ENEV

BACKGROUND

Alloantibodies that define some high-prevalence MNS antigens are made by people with glycophorin A (GPA) altered by a single-amino-acid change or replacement of amino acids from part of the Pseudoexon 3 of GYP*B. The finding of a patient whose plasma contained a novel alloanti-En(a)FR prompted this study.

RESULTS

The patient's serum contained an alloantibody to a high-prevalence antigen, resistant to papain, ficin, trypsin, alpha-chymotrypsin, or dithiothreitol. The antibody was strongly reactive with all panel red blood cells (RBCs) tested, showed reduced reactivity with ENEP- and ENAV- RBCs, and was nonreactive with M(k)M(k), En(a-), GP.Hil/GP.Hil, and GP.JL/M(k) RBCs. The patient's RBCs typed M+N-S+s-, Wr(a-b+(w)), ENEP-, and ENAV-. These results indicated that the antibody recognized a new high-prevalence antigen in the MNS system. Sequencing of DNA prepared from the patient's white blood cells revealed a GYP*A nucleotide substitution of 242T>G (predicted to change Val62 of GPA to Gly). This change ablates an RsaI restriction enzyme site and polymerase chain reaction-restriction fragment length polymorphism confirmed that the proband was homozygous for Nucleotide 242G.

CONCLUSIONS

We describe a novel high-prevalence MNS antigen, characterized by Val62 in GPA and named ENEV. The absence of the antigen is associated with Gly62. The change explains the weakened reactivity of the patient's serum with ENEP- and ENAV- RBCs and nonreactivity with anti-ENEP and anti-ENAV against her RBCs. The ENEV antigen has been assigned the ISBT number MNS45.

[The red blood cell antigen terminologies]

Since the discovery of blood groups in humans, several hundred new red blood cell antigens have been identified. Multiple terminology modes have been used to denote each new antigen identified, but without any consistent rules, nor international consensus. This was largely due to the many discoverers of these antigens, using either letters of the alphabet, numbers, part of the patient or donor's name, place of discovery or animal names. Besides, alternative terminologies for the Rh system were implemented in the middle of the twentieth century (Rosenfield, Fisher-Race, Wiener). The International Society of Blood Transfusion described for the first time in 1980 the advantages of an alphanumeric and homogeneous nomenclature, keeping with the genetic bases of blood groups, as well as a classification of all RBC antigens within several families. A variant of this new terminology, exclusively numerical, was simultaneously established, mainly designed for computer data exchange. Nearly 30 years later, 308 red blood cell antigens are described within 30 systems, 12 collections, one 700 series and one 901 series of blood groups. Any person involved in the field of immuno-haematology must master both the usual and international nomenclatures. The Wiener nomenclature used for Rh haplotypes, still largely used today, is also important to be known. The systematic use of the international nomenclature should be strongly encouraged, either in the labelling of blood products, clinical laboratory reports or blood type cards.

Red cell genotyping and the future of pretransfusion testing

Over the past 20 years the molecular bases of almost all the major blood group antigens have been determined. This research has enabled development of DNA-based methods for determining blood group genotype. The most notable application of these DNA-based methods has been for determining fetal blood group in pregnancies when the fetus is at risk for hemolytic disease of the fetus and newborn. The replacement of all conventional serologic methods for pretransfusion testing by molecular methods is not straightforward. For the majority of transfusion recipients matching beyond ABO and D type is unnecessary, and the minority of untransfused patients at risk of alloimmunization who would benefit from more extensively blood group–matched blood cannot be identified reliably. Even if a method to identify persons most likely to make alloantibodies were available, this would not of itself guarantee the provision of extensively phenotype-matched blood for these patients because this is determined by the size and racial composition of blood donations available for transfusion. However, routine use of DNA-based extended phenotyping to provide optimally matched donations for patients with preexisting antibodies or patients with a known predisposition to alloimmunization, such as those with sickle cell disease, is widely used.

Transfusion in the age of molecular diagnostics

DNA-based tests are increasingly being used to predict a blood group phenotype to improve transfusion medicine. This is possible because genes encoding 29 of the 30 blood group systems have been cloned and sequenced, and the molecular bases associated with most antigens have been determined. RBCs carrying a particular antigen, if introduced into the circulation of an individual who lacks that antigen (through transfusion or pregnancy), can elicit an immune response. It is the antibody from such an immune response that causes problems in clinical practice and the reason why antigen-negative blood is required for safe transfusion. The classical method of testing for blood group antigens and antibodies is hemagglutination; however, it has certain limitations, some of which can be overcome by testing DNA. Such testing allows conservation of antibodies for confirmation by hemagglutination of predicted antigen-negativity. High-throughput platforms provide a means to test relatively large numbers of donors, thereby opening the door to change the way antigen-negative blood is provided to patients and to prevent immunization. This review summarizes how molecular approaches, in conjunction with conventional hemagglutination, can be applied in transfusion medicine.

Applications and Experience with PCR-Based Assays to Predict Blood Group Antigens

DNA-based tests are increasingly being used to predict a blood group phenotype. This is possible because genes encoding 29 of the 30 blood group systems have been cloned and sequenced, and the molecular bases associated with most antigens have been determined. RBCs carrying a particular antigen, if introduced into the circulation of an individual who lacks that antigen, can elicit an immune response. It is the antibody from such an immune response that causes problems in clinical practice and the reason why antigen-negative blood is required for safe transfusion. The classical method of testing for blood group antigens and antibodies is hemagglutination; however, it has certain limitations, some of which can be overcome by testing DNA. Such testing allows conservation of antibodies for confirmation by hemagglutination of predicted antigen-negativity. High-throughput platforms provide a means to test relatively large numbers of donors, thereby opening the door to change the way antigen-negative blood is provided to patients. This chapter discusses how molecular approaches can be applied in transfusion medicine, and summarizes experiences of using laboratory developed tests and DNA arrays at the New York Blood Center.

Single base extension in multiplex blood group genotyping

Transfusion recipients who become alloimmunized to blood group antigens require antigen-negative blood to limit adverse transfusion reactions. An alternative strategy to phenotyping blood is to assay genomic DNA for the associated single nucleotide polymorphisms (SNPs). A multiplex PCR coupled with a single base oligonucleotide extension assay using genomic DNA can identify SNPs related to D, C/c, E/e, S/s, K/k, Kp(a/b), Fy(a/b), Fy0 (-33 promoter silencing polymorphism), Jk(a/b), Di(a/b), and HPA-1a/b. Using this technology, individual SNP call rates vary from 98 to 100%. The platform has the capacity to genotype thousands of samples per day. The suite of SNPs provides rapid data for both blood donors and transfusion recipients and is poised to change whose blood is provided for potential transfusion recipients. The potential to dramatically lower the incidence of alloimmunization and to avoid serious hemolytic complications of transfusions can be realized with the implementation of this technology.

Large-scale blood group genotyping: clinical implications

The molecular background of blood group antigen expression of the major clinically significant blood group antigens has been largely accomplished. Despite this large body of work, blood group phenotype prediction by genotyping has a marginal supporting role in the routine blood bank. It has however had a major impact in the prenatal determination of fetal blood group status in the management of haemolytic disease of the fetus and newborn. In the past few years several high throughput systems have been in development that have the potential capacity to perform genotyping on a mass scale. Such systems have been designed for use on donor- and patient-derived DNA and provide much more comprehensive information regarding an individuals blood group than is possible by using serological methods alone. DNA-based typing methodology is easier to standardize than serology and has the potential to replace it as a front line diagnostic in blood banks. This review overviews the current situation in this area and attempts to predict how blood group genotyping will evolve in the future.

Novel GYP(A-B-A) hybrid gene in a DANE+ person who made an antibody to a high-prevalence MNS antigen

BACKGROUND

The glycophorin (GP) molecule associated with the GP.Dane phenotype is a GP(A-B-A) hybrid that contains some amino acids encoded by the Pseudoexon 3 of GYPB and Asn(45) of GPA and carries the low-prevalence MNS antigens DANE and Mur. Serum from a woman of English ancestry contained an immunoglobulin M alloantibody to a high-prevalence MNS antigen, and the purpose of this study was to identify the molecular basis of her phenotype.

STUDY DESIGN AND METHODS

Hemagglutination, Western blotting, and DNA analyses were performed by standard methods.

RESULTS

Tests of the proband's RBCs with monoclonal antibodies indicated a change of amino acids between positions 27 and 55 of GPA. Her RBCs expressed M, s, Mur, and DANE antigens and were M(g)-negative. The antigen recognized by her antibody was sensitive to treatment with papain, ficin, and trypsin and resistant to alpha-chymotrypsin and dithiothreitol. Sequencing of DNA from the proband revealed a sequence of nucleotides identical to the GYP(A-B-A) encoding GP.Dane but without the adenyl nucleotide substitution, which has been predicted to change Ile(46) of GPA to Asn(45). Testing of her immediate family revealed the presence of an M(k) gene.

CONCLUSION

The proband had a novel GYP(A-B-A) encoding a DANE+ GP that is in cis to GYPB(s) and in trans to M(k). The high-prevalence antigen lacking from this GP.Dane phenotype and recognized by the proband's serum is called ENDA (ISBT Number MNS44). Our results indicate that the change of Ile(46) of GPA to Asn(45) of GP.Dane is not required for expression of the DANE antigen.

Blood doping in athletes--detection of allogeneic blood transfusions by flow cytofluorometry

Athletes may undergo blood transfusion to increase their red cell mass and the oxygen carrying capacity of their blood in order to confer a competitive advantage. Allogeneic transfusions are normally mismatched at one or more minor blood group antigens. The most sensitive and accurate method known to detect this form of blood doping is flow cytometry. Low percentages of antigen-positive and antigen-negative red blood cells (RBCs) can be quantitated using suitable specific alloantibodies and careful analysis. By testing blood samples taken at various times, a reduction in the percentage of a minor population of RBCs will indicate transfusion has occurred.

McLeod syndrome: a neurohaematological disorder

The X-linked McLeod syndrome is defined by absent Kx red blood cell antigen and weak expression of Kell antigens, and this constellation may be accidentally detected in routine screening of apparently healthy blood donors. Most carriers of this McLeod blood group phenotype have acanthocytosis and elevated serum creatine kinase levels and are prone to develop a severe neurological disorder resembling Huntington's disease. Onset of neurological symptoms ranges between 25 and 60 years, and the penetrance of the disorder appears to be high. Additional symptoms of the McLeod neuroacanthocytosis syndrome that warrant therapeutic and diagnostic considerations include generalized seizures, neuromuscular symptoms leading to weakness and atrophy, and cardiopathy mainly manifesting with atrial fibrillation, malignant arrhythmias and dilated cardiomyopathy. Therefore, asymptomatic carriers of the McLeod blood group phenotype should have a careful genetic counseling, neurological examination and a cardiologic evaluation for the presence of a treatable cardiomyopathy.

Three new high-prevalence antigens in the Cromer blood group system

BACKGROUND

The Cromer blood group system consists of nine high-prevalence and three low-prevalence antigens carried on decay-accelerating factor (DAF). This report describes three new Cromer high-prevalence antigens, named ZENA, CROV, and CRAM.

STUDY DESIGN AND METHODS

Sequence analyses were performed on DNA from three probands whose serum samples each contained an alloantibody to a high-prevalence antigen in the Cromer blood group system. Polymerase chain reaction-restriction fragment length polymorphism analysis to detect the mutation encoding the CROV- phenotype was performed on 100 Croatian donors. To map the respective epitopes, DAF deletion mutants were tested by immunoblotting with eluates containing the antibodies.

RESULTS

In each proband, sequence analysis revealed a single-nucleotide substitution in DAF: ZENA, 726T>G mutation, predicted change His242Gln; CROV, 466G>A mutation, predicted change Glu156Lys; and CRAM, 740A>G mutation, predicted change Gln247Arg. By analysis of DAF deletion mutants, the CROV antigenic determinant mapped to the complement control protein (CCP) domain 2, which is encoded by exon 3, whereas ZENA and CRAM mapped to CCP4, which is encoded by exon 6.

CONCLUSION

This study describes three novel high-prevalence antigens in the Cromer blood group system each characterized by a predicted single-amino-acid substitution. The antigens have been assigned the following International Society of Blood Transfusion (ISBT) numbers: ZENA is CROM13, CROV is CROM14, and CRAM is CROM15.

Two missense mutations in the CD44 gene encode two new antigens of the Indian blood group system

BACKGROUND

Blood samples were referred over a 10-year period from five patients whose serum samples contained antibodies to unidentified high-incidence antigens. Three patients (A, B, C) were of Moroccan origin and their antibodies and red blood cells (RBCs) were mutually compatible, but incompatible with those of the other two patients (D, E), who were of Pakistani origin. The antibodies and RBCs of D and E were mutually compatible, but incompatible with those of Patients A, B, and C. All the antibodies were detected during pregnancy.

STUDY DESIGN AND METHODS

Serologic tests, including the use of enzyme-treated and chemically modified RBCs, suggested a relationship to CD44 (Indian blood group system). The monoclonal antibody immobilization of erythrocyte antigens (MAIEA) assay with monoclonal CD44 antibodies, immunoblotting of RBC membranes, and CD44 gene sequencing were carried out.

RESULTS

Positive reactions in the MAIEA assay confirmed that the patients' antibodies are directed at CD44. Immunoblotting with two of the antibodies gave positive reactions of identical size to monoclonal anti-CD44 and failed to react with the RBCs of a CD44-deficient patient. One of the antibodies reacted with purified CD44. Sequencing of Exons 1 to 5 of CD44 revealed 255C>G in Exon 3 for A, B, and C encoding H85Q and 488C>A in Exon 5 for D and E encoding T163K [corrected]

CONCLUSION

Two novel CD44 antigens of high incidence have been identified: IN3 (INFI) and IN4 (INJA) in the IN (Indian) blood group system. Lack of IN3 and IN4 results from homozygosity for mutations encoding H85Q and T163R in CD44, respectively.

Production of soluble recombinant proteins with Kell, Duffy and Lutheran blood group antigen activity, and their use in screening human sera for Kell, Duffy and Lutheran antibodies

The aim of this study was to show that soluble recombinant (sr) proteins can mimic blood group antigens and be used to screen human sera for blood-group-specific antibodies. The blood of all pregnant women and pretransfusion patients should be screened for blood-group-specific antibodies to identify and monitor pregnancies at risk of haemolytic disease of the foetus and newborn (HDFN), and to prevent haemolytic transfusion reactions. Current antibody screening and identification methods use human red blood cell panels, which can complicate antibody identification if more than one antibody specificity is present. COS-7 cells were transfected to produce sr forms of the extracellular domains of the red blood cell membrane proteins that express Kell, Duffy or Lutheran blood group antigens. These sr proteins were used to screen for and identify anti-Kell, anti-Duffy or anti-Lutheran blood-group-specific allo-antibodies in human sera by haemagglutination inhibition and in solid-phase enzyme-linked immunosorbent assays (ELISAs). There is a positive correlation (correlation coefficient 0.605, P value 0.002) between antibody titre by standard indirect antiglobulin test (IAT) and signal intensity in the ELISA test. This work shows that sr proteins can mimic blood group antigens and react with human allogeneic antibodies, and that such proteins could be used to develop solid-phase, high-throughput blood group antibody screening and identification platforms.