Partial matching of blood group antigens to reduce alloimmunization in Western India

The Distribution Patterns of Rhesus (Rh) Antigens

INTRODUCTION

The determination of one's blood group is dictated by the inheritance-based diversity in the presence or absence of RBC antigens on the surface. Extended Rhesus (Rh) antigens are the most clinically relevant antigens of blood group systems after the ABO blood group system in transfusion medicine. The aim of this study was to serologically assess the prevalence of extended Rh antigens across diverse blood group systems.

METHODS

A total of 2043 samples were tested for the ABO blood group and Rh typing with monoclonal antisera. The Rh phenotyping (C, c, E, e ) was performed on all the samples.

RESULTS

The most frequently observed ABO blood group was O (36.5%), while AB (13.6%) was identified as the least prevalent. Positive Rh D antigen was found in 91.6% of tested samples, while 8.4% were Rh D-negative. The most frequently encountered antigen was e, followed by D, while the least prevalent was E.

DISCUSSION

Establishing a Rh phenotype repository for blood donors and conducting Rh phenotype assessments as part of pretransfusion testing before initiating the initial blood transfusion for each patient could significantly lower the patients' incidence of alloimmunization.

Determination of the Rh/Kell phenotypes in donor as well as patients might be significant to provide phenotype-matched blood to cancer patients: A retrospective analysis from a tertiary care oncology center in North India

BACKGROUND

Multiple reports are available from different parts of the globe indicating the incidences of alloimmunization and blood transfusion-related reactions, which emphasizes the need for phenotyping and providing antigen-matched safe blood.

AIMS AND OBJECTIVES

This study aims to determine the frequency of Rh and Kell antigens and phenotype for both donors and patients to propose the importance of providing Rh Kell phenotype cross-matched packed red blood cell (RBC) units to minimize the alloimmunization and transfusion reactions.

MATERIALS AND METHODS

Ten thousand blood donors and four thousand patients were investigated between October 2017 and July 2019. Each donor unit was tested for blood grouping, antibody screening, and Rh Kell antigen Phenotyping, and the blood unit was issued after the patient's blood grouping, antibody screening by 3 cell panels, and Rh Kell antigen phenotyping followed by cross-matching with an Rh Kell-matched phenotype RBC unit.

RESULTS

Nine thousand four hundred and fifty-two donors were D positive (94.5%) while 548 tested D negative (5.5%). Overall Rh and K antigens frequencies in donors were: "e" (98%) >"D" (94.5%) >"C" (86.6%) > "c" (57.5%) >"E" (18.8%) >K (0.98%). Among patients, 3762 tested D positive (94.05%), and 238 tested D negative (5.95%). Overall Rh and K antigens frequencies in patients were: "e" (98.5%) >"D" (94.05%) >"C" (90.2%) >"c" (51%) >"E" (18.2%) >K (1.8%).

CONCLUSION

Our study has given us more clarity on the prevalence of major Rh and K antigens in our donor as well as patient populations, highlighting the similarities as well as differences. This variance holds a great significance, since such donor units when transfused into patients may lead to alloimmunization and adverse transfusion reactions. Hence, the determination of Rh and Kell phenotypes and providing phenotype-matched blood will help prevent such events.

An assessment of clinical and laboratory impact in a resource constraint setting: Does Rh and Kell phenotyping of donor units complement type and screen method of compatibility testing?

BACKGROUND AND AIM

Despite knowing benefits of extended phenotyping, a vast majority feel that phenotype matched units add to the cost of blood banking. The purpose of this study was to discuss advantages and disadvantages of performing Rh Kell phenotyping in Indian scenario.

MATERIALS AND METHODS

This was a prospective, observational study conducted at a tertiary healthcare center between July 2014 and February 2020. All consecutive whole blood donors and all consecutive patients whose samples were sent for Rh-Kell phenotyping were included for calculating antigen, phenotype and gene frequencies. For rate of alloimmunization in patients transfused with phenotype matched units, all patients who were given Rh-Kell phenotype matched transfusions were included in the prophylactic antigen matched (PAM) category and those who were given random units were included in the non-PAM category.

RESULTS

A total of 37,588 donors and 258 patients were included in the study for calculation of antigen, phenotype and gene frequencies. Percentage similarity of phenotypes between patient and donor populations was 33.8%. For rate of alloimmunization, results of a total of 31,991 patient samples revealed 0.94% prevalence of unexpected antibodies; highest against the Rh system. Three patients in the non-PAM category and one in the PAM category were alloimmunized during follow-up. Significant clinical and laboratory impact of phenotyping was observed in terms of reduced turnaround time and consumption of resources.

CONCLUSION

Rh-Kell phenotyping of donors can prevent alloimmunization, reduce cost burden on the patient and the laboratory and help the laboratory personnel in smooth routine testing.

Red cell antigen phenotypes in blood donors & thalassaemia patients for creation of red cell antigen-matched inventory

Background & objectives:

Patients with thalasssaemia are at a risk of alloimmunization and the presence of RBC alloantibodies further complicates transfusion therapy. Matching for the critical antigens of Rh, Kell, Kidd and Duffy blood group systems has been shown to minimize alloimmunization. The aim of the present study was to create a database of extensively typed donors for clinically significant and common blood group antigens of Rh, Kidd, Kell and Duffy systems for transfusion therapy of multitransfused thalassaemic patients.

Methods:

Five hundred O group regular blood donors were phenotyped for Rh, Kell, Duffy and Kidd blood group antigens using haemagglutination technique. Eighty four non-alloimmunized and 15 alloimmunized thalassaemia major patients with known antigenic profiles (determined by polymerase chain reaction with sequence-specific primers) were selected for this study.

Results:

By analyzing antigen profiles of 500 O group regular donors, a database of 193 donors matching perfectly for Rh, Duffy, Kell and Kidd antigens was prepared for 15 alloimmunized patients. For non-alloimmunized 84 thalassaemic patients, a database of 405 donors was created.

Interpretation & conclusions:

A database of 500 regular blood donors phenotyped for common antigens of Rh, Duffy, Kell and Kidd blood group systems was created, which would be useful in providing extended antigen-matched RBCs for thalassaemia patients. This will improve the quality and effectiveness of transfusion therapy.

Molecular genotyping of clinically important blood group antigens in patients with thalassaemia

Background & objectives:

In multitransfused thalassaemic patients, haemagglutination fails to phenotype the patient's blood group antigens due to the presence of donor-derived erythrocytes. DNA-based methods can overcome the limitations of haemagglutination and can be used to determine the correct antigen profile of these patients. This will facilitate the procurement of antigen-matched blood for transfusion to multitransfused patients. Thus, the aim of this study was to compare the serological phenotyping of common and clinically important antigens of Rh, Duffy, Kell, Kidd and MNS blood group systems with molecular genotyping amongst multitransfused thalassaemic patients.

Methods:

Blood samples from 200 patients with thalassaemia and 100 ‘O’ group regular blood donors were tested using standard serological techniques and polymerase chain reaction-based methods for common antigens/alleles (C, c, D, E, e, Fy^a, Fy^b, Jk^a, Jk^b, K, k, M, N, S, s).

Results:

Genotyping and phenotyping results were discordant in 77 per cent of thalassaemic patients for five pairs of antithetical antigens of Rh, Duffy, Kell and Kidd blood group systems. In the MNS blood group system, 59.1 per cent of patients showed discrepancy. The rate of alloimmunization among thalassaemics was 7.5 per cent.

Interpretation & conclusions:

Molecular genotyping enabled the determination of the actual antigen profile in multitransfused thalassaemia patients. This would help reduce the problem of alloimmunization in such patients and would also aid in the better management of transfusion therapy.

Evaluation of the New Lateral Flow Card MDmulticard® Basic Extended Phenotype in Routine Clinical Practice

Background

Transfusion emergencies and critical situations require specifically designed devices to simplify and optimize the standard procedures. In addition, matching antigens over and above ABO-Rh-K would be beneficial.

Methods

Routine blood samples were collected in four immunohematology centers and tested with the new MDmulticard Basic Extended Phenotype for the simultaneous detection of the Duffy, Kidd, and Ss antigens, according to the principle of the lateral flow. Results were compared with those obtained using routine serology methods. Discrepancies were analyzed by molecular techniques/genotyping.

Results

310 samples were tested (167 donors; 75 patients; 28 subjects with positive direct antiglobulin test (DAT); 15 newborns; 25 previously transfused patients). The 285 samples with non-mixed-field reaction yielded 1,710 antigen results with 8 discrepancies (0.47%) six of which in DAT-positive subjects: three false-positive (Fy^a) for MDmulticard, and two false-positive (Fy^a) plus three false-negative (Fy^b) for the reference methods (MDmulticard PPA for donors/patients/newborns: 99.82%; negative percent agreement: 100%; sensitivity: 100%; specificity: 99.39%, positive predictive value: 99.75%; negative predictive value: 100%). The MDmulticard detected mixed-field in 15 antigen reactions from 13 transfused patients, undetected by the comparative method, with the opposite result in 8 antigens (5 patients).

Conclusion

The MDmulticard Basic Extended Phenotype met the criteria prescribed for the testing of donor, patient, DAT-positive, and newborn samples in transfusion laboratory routine.

Evolution of technology for molecular genotyping in blood group systems

The molecular basis of the blood group antigens was identified first in the 1980s and 1990s. Since then the importance of molecular biology in transfusion medicine has been described extensively by several investigators. Molecular genotyping of blood group antigens is one of the important aspects and is successfully making its way into transfusion medicine. Low-, medium- and high-throughput techniques have been developed for this purpose. Depending on the requirement of the centre like screening for high- or low-prevalence antigens where antisera are not available, correct typing of multiple transfused patients, screening for antigen-negative donor units to reduce the rate of alloimmunization, etc. a suitable technique can be selected. The present review discusses the evolution of different techniques to detect molecular genotypes of blood group systems and how these approaches can be used in transfusion medicine where haemagglutination is of limited value. Currently, this technology is being used in only a few blood banks in India. Hence, there is a need for understanding this technology with all its variations.