Transfusion Support of Minority Patients: Extended Antigen Donor Typing and Recruitment of Minority Blood Donors

Red Cell Alloimmunisation Among Sickle Cell Disease and Thalassemia Patients Following Rh- and K-Matched Red Cell Transfusion in Southwestern Saudi Arabia: A Multicenter Study

Background

Alloimmunisation remains a major consequence of blood transfusion among sickle cell disease (SCD) and thalassemia patients due to the exposure to non-self-red blood cell (RBC) antigen. The complication is associated with transfusion reactions and delayed transfusion procedure because of the difficulty of finding compatible blood. This study aims to determine the prevalence of alloimmunisation to RBC and alloantibody specificities among SCD and thalassemia patients in, an endemic area of SCD and thalassemia, Jazan province of Saudi Arabia, from three major hospitals.

Methods

This is a retrospective, multicenter cross-sectional study conducted on 1027 patients with SCD and thalassemia, which received Rh/K matched transfusions in 2019 in the three centers. Demographic data and medical records of participants from three transfusion institutions were collected and analysed.

Results

A total of 1027 were enrolled in the cohort; 906 (88.2%) and 121 (11.8%) patients with SCD and thalassemia, respectively. There were 483 (47%) males and 544 (53%) females with median age of 15 (range 1-48). Among the studied population, 78 were alloimmunised with an overall alloimmunisation rate of 7.6%. These patients developed a total of 108 alloantibodies, and anti-E was the most detected antibody (25.9%) followed by anti-K (24.1%).

Conclusion

The overall rate of alloimmunisation to RBC antigen among the studied population in Jazan was low compared to other areas in the country. Most alloantibodies detected were against E and K antigens. The knowledge of most encountered alloantibodies in our population will aid in selecting the most appropriate antigen-negative red cells. Further research, however, is needed to explore factors associated with residual risk of alloimmunisation in these patients.

Neighborhood ethnic density and disparities in proximal blood donation opportunities

BACKGROUND

Despite being the largest racial/ethnic minority group in the United States, Hispanic/Latinos (H/L) are significantly underrepresented among blood donors. A lack of proximal blood donation opportunities may be one factor contributing to these disparities. However, few studies have investigated this possibility.

STUDY DESIGN AND METHODS

Proprietary data on mobile blood collections in Maricopa County, Arizona, were gathered for the period of January 01, 2022 to April 30, 2022 and paired with census tract information using ArcGIS. Maricopa County encompasses the city of Phoenix with a total population of approximately 4.5 million people, including 1.5 million H/L residents. Blood drive count was regressed on H/L ethnic density and total population, and model estimates were exponentiated to obtain odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

During the specified period, approximately 27,000 red blood cell units were collected through mobile drives. Consistent with expectations, when controlling for total neighborhood population, each 10% increase in H/L ethnic density lowered the odds of having a blood drive in the corresponding neighborhood by 12% (OR = 0.88, 95% CI (0.83, 0.92), p < .001).

DISCUSSION

These findings provide initial evidence of fewer proximal donation opportunities in areas with greater H/L population density which may contribute to H/L underrepresentation in blood donation and the need for more inclusive collection efforts. Improved access to blood collection is modifiable and could help to increase the overall blood supply, enhance the ability to successfully match specific blood antigen needs of an increasingly diverse population, and bring about a more resilient blood system.

Advancing Understandings of Blood Donation Motivation and Behavior

In this review, we provide critical analysis of social science research into blood donation motivation and behavior. We first share an understanding of the existing literature and recommendations for future research collectively developed by members of the Working Group on Blood Donors and the Supply: Diversifying while Maintaining the Donor Pool, Donor Selection, and Optimizing Blood Availability and Safety, as part of the National Heart, Lung, and Blood Institute's 2022 State of the Science in Transfusion Medicine symposium. Then, rather than aim for a comprehensive treatment, we review 4 newer manuscripts that exemplify aspects of the group's recommendations and report results from countries where the blood supply is based on voluntary, nonremunerated donations. From the substantial existing literature, we selected: (1) a study that employed motivational interviewing techniques, thematic analysis, and surveys to link donation motivations and barriers reported by diverse young donors in the United States to actual donation behavior over a year of subsequent eligibility; (2) a survey regarding donation motivations and barriers and monetary amounts associated with willingness to participate in whole blood, plasma, or platelet collection; (3) a survey-based assessment of various emotional states reported by donors at 2 time points during donation and the relationship between emotional experience and subsequent vasovagal reactions; and (4) an interpretive discourse analysis of blood collection agency messaging to donors and the public in the beginning of the COVID-19 pandemic. We close by noting several challenges posed by the structure of the United States blood system and the current funding environment to conducting rigorous research and translating findings into practice.

Red Blood Cell Alloimmunizations in Thalassaemia Patients With Regular Transfusion in China: a Systematic Review and Meta-Analysis

OBJECTIVE

The development of red blood cell alloimmunization intensifies transfusion complication in thalassaemia patients. The purpose of this paper is to evaluate the existing evidence on the prevalence of erythrocyte alloimmunization in China by meta-analysis. We systematically searched cross-sectional studies regarding the alloimmunization of thalassaemia patients with regular blood transfusion in China from year 2000 to May 2021 in the Cochrane library, PubMed, EMBASE, Web of Science, and Chinese databases including CNKI, Wanfang Data, Vip and CBM. Data extraction and quality evaluation of the included studies were performed. Meta-analysis was performed using the DerSimonian and Laird random-effects models with inverse variance weighting. The presence of publication bias was tested by Egger's test, and the methodological quality of each included article was evaluated by the criteria specific to prevalence studies.

RESULTS

A total of 1874 patients and 263 alloantibodies from 11 studies were identified and included in the meta-analysis. The proportion of alloantibodies against antigens belonging to the Rh, MNSs and Kidd systems were as high as 70.3%, 17.9%, and 6.5%, respectively. Meta-analysis showed that the overall prevalence of alloimmunization among transfusion-dependent thalassaemia patients in China is 11.4% (95%CI: 7.2%∼16.3%).

CONCLUSIONS

The characteristics of red blood cell alloimmunization among thalassaemia patients with regular transfusion in China differ greatly from those in other countries. Therefore, transfusion strategies shall be actively adapted in line with thalassaemia patients in China to minimize the risk of alloimmunization.

Transfusion management of Africans with RHD variants in China

The presence of D variant among minorities could produce a higher rate of alloimmunization observed in patients from this group. This is partly due to the ethnic and racial specificity of RHD variants and the limited availability of Rh-matched blood donors. Approximately half a million African migrants in China carrying distinct Rh blood type composition have presented to the health care system with an imperative safety requirement of blood transfusion among 1.3 billion Chinese individuals. We depict the clinically significant RHD alleles among African migrants living in China and identify the genetic similarities and disparities to Chinese. We discussed practical strategies to manage the unique transfusion needs of African migrants in China.

RBCeq: A robust and scalable algorithm for accurate genetic blood typing

Background

While blood transfusion is an essential cornerstone of hematological care, patients requiring repetitive transfusion remain at persistent risk of alloimmunization due to the diversity of human blood group polymorphisms. Despite the promise, user friendly methods to accurately identify blood types from next-generation sequencing data are currently lacking. To address this unmet need, we have developed RBCeq, a novel genetic blood typing algorithm to accurately identify 36 blood group systems.

Methods

RBCeq can predict complex blood groups such as RH, and ABO that require identification of small indels and copy number variants. RBCeq also reports clinically significant, rare, and novel variants with potential clinical relevance that may lead to the identification of novel blood group alleles.

Findings

The RBCeq algorithm demonstrated 99·07% concordance when validated on 402 samples which included 29 antigens with serology and 9 antigens with SNP-array validation in 14 blood group systems and 59 antigens validation on manual predicted phenotype from variant call files. We have also developed a user-friendly web server that generates detailed blood typing reports with advanced visualization (https://www.rbceq.org/).

Interpretation

RBCeq will assist blood banks and immunohematology laboratories by overcoming existing methodological limitations like scalability, reproducibility, and accuracy when genotyping and phenotyping in multi-ethnic populations. This Amazon Web Services (AWS) cloud based platform has the potential to reduce pre-transfusion testing time and to increase sample processing throughput, ultimately improving quality of patient care.

Funding

This work was supported in part by Advance Queensland Research Fellowship, MRFF Genomics Health Futures Mission (76,757), and the Australian Red Cross LifeBlood. The Australian governments fund the Australian Red Cross Lifeblood for the provision of blood, blood products and services to the Australian community.

Generation of 'designer erythroblasts' lacking one or more blood group systems from CRISPR/Cas9 gene-edited human-induced pluripotent stem cells

Despite the recent advancements in transfusion medicine, red blood cell (RBC) alloimmunization remains a challenge for multiparous women and chronically transfused patients. At times, diagnostic laboratories depend on difficult-to-procure rare reagent RBCs for the identification of different alloantibodies in such subjects. We have addressed this issue by developing erythroblasts with custom phenotypes (Rh null, GPB null and Kx null/Kell low) using CRISPR/Cas9 gene-editing of a human induced pluripotent stem cell (hiPSC) parent line (OT1-1) for the blood group system genes: RHAG, GYPB and XK. Guide RNAs were cloned into Cas9-puromycin expression vector and transfected into OT1-1. Genotyping was performed to select puromycin-resistant hiPSC KOs. CRISPR/Cas9 gene-editing resulted in the successful generation of three KO lines, RHAG KO, GYPB KO and XK KO. The OT1-1 cell line, as well as the three KO hiPSC lines, were differentiated into CD34+ CD41+ CD235ab+ hematopoietic progenitor cells (HPCs) and subsequently to erythroblasts. Native OT1-1 erythroblasts were positive for the expression of Rh, MNS, Kell and H blood group systems. Differentiation of RHAG KO, GYPB KO and XK KO resulted in the formation of Rh null, GPB null and Kx null/Kell low erythroblasts, respectively. OT1-1 as well as the three KO erythroblasts remained positive for RBC markers-CD71 and BAND3. Erythroblasts were mostly at the polychromatic/ orthochromatic stage of differentiation. Up to ~400-fold increase in erythroblasts derived from HPCs was observed. The availability of custom erythroblasts generated from CRISPR/Cas9 gene-edited hiPSC should be a useful addition to the tools currently used for the detection of clinically important red cell alloantibodies.

Increased Prevalence of Alloimmunization in Sickle Cell Disease? Should We Restore Blood Donation in French Guiana?

Patients with sickle cell disease often undergo frequent blood transfusions. This increases their exposure to red blood cell alloantigens of donor units, thus making it more likely that they produce alloantibodies. This cross-sectional study aimed to describe the prevalence of allo-immunization in patients with sickle cell disease who were monitored at Cayenne Hospital in 2016. Of the 451 patients recruited during the study period, 238 (52.8%) were female. There were 262 (58.1%) homozygous sickle cell and 151 (33.5%) compound heterozygous sickle cell patients. The median age of the participants was 23.09 years (range, 0.5–68). We noted different red blood cell extended phenotypes: -in the Duffy system, the Fy^a- Fy^b–profile was found in 299 patients (66%);—for the Kidd system, the most represented profile was Jka+ Jkb-, with 213 patients (47%). The Jka antigen was present in 355 patients;—in the MNS system, the S-s+ profile was found in 297 patients (66%);—the Lea antigen of the Lewis system was absent in 319 patients. The most frequent Rh phenotype in our patients was D+ C- E- c+ e+ K-, representing 51% of the patients. A total of 6,834 transfused packed red blood cell units were recorded. Sixty-eight patients (23%; 95% confidence interval, 20–25%) had detectable RBC alloantibodies. In multivariate logistic regression, only the mean number of single transfusions was statistically higher for the alloimmunized patients (p < 0.04). Thirteen (19%) of the patients with alloimmunization developed a delayed hemolytic transfusion reaction, thus representing 4.4% of the total number of transfused patients. Whether differences between donors from France vs. recipients from French Guiana could explain this high prevalence of alloimmunization to be examined. In conclusion, careful transfusion strategies for patients with RBC alloantibodies should allow further reduction of the rate of alloimmunization.

Blood group genotyping in alloimmunized multi-transfused thalassemia patients from Iran

Objectives

Serological methods may not be reliable for RBC antigen typing, especially in multi‐transfused patients. The blood group systems provoking the most severe transfusion reactions are mainly Rh, Kell, Kidd, and Duffy. We intended to determine the genotype of these blood group system antigens among Iranian alloimmunized thalassemia patients using molecular methods and compare the results with serological phenotyping.

Methods

Two hundred patients participated in this study. Blood group phenotype and genotype were determined using the serological method and PCR‐SSP, respectively. The genotypes of patients with incompatibility between phenotype and genotype were re‐evaluated by RFLP‐PCR and confirmed by DNA sequencing.

Results

Discrepancies between phenotype and genotype results were found in 132 alleles and 83 (41.5%) patients; however, there was complete accordance between the three genotyping methods. Most discrepancies were detected in Rh and Duffy systems with 47 and 45 cases, respectively, and the main discrepancy was in the FY*B/FY*B allele when serologically showed Fy(a+b+). All 39 undetermined phenotypes, due to mixed‐field reactions, were resolved by molecular genotyping.

Conclusion

Molecular genotyping is more reliable compared with the serological method, especially in multi‐transfused patients. Therefore, the addition of blood group genotyping to serological assays can lead to an antigen‐matched transfusion in these patients.

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

BACKGROUND AND OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Racial/ethnic disparities among women receiving intrauterine transfusions for alloimmunization at a single fetal treatment center

Disparities are prevalent in numerous areas of healthcare. We sought to investigate whether there were racial/ethnic disparities among pregnant women with the most severe form of alloimmunization who require intrauterine transfusions (IUT). We reviewed patients who underwent IUT for alloimmunization at a single fetal treatment center between 2015 and 2020. This "IUT cohort" was compared to an "Alloimmunization cohort": patients seen at our institution with a diagnosis of alloimmunization during pregnancy, who did not receive IUT. We collected maternal demographics including self-identified race/ethnicity and primary language, transfusion, and antibody characteristics. The cohorts were compared using unpaired t-tests, Mann-Whitney tests, and Fischer's exact tests, as appropriate. The IUT cohort included 43 patients and the alloimmunization cohort included 1049 patients. Compared to the alloimmunization cohort, there were significantly more patients of Latina descent in the IUT cohort (23.3% vs. 3.4%, p < .0001), and more non-English speakers (18.6% vs. 4.6%, p = .001). Twenty-one percent (9/43) of patients had immigrated to the United States, all of whom had pregnancies or miscarriages in their country of origin. A third of patients had new antibodies identified on serial screens during the current pregnancy. Significantly more women of Latina ethnicity and non-English speakers required IUTs compared to the cohort of women with alloimmunization. Insufficient access to care prior to arriving in the United States and among racial and ethnic minorities in the United States may contribute to these findings. Providers should be cognizant of potential, racial, and ethnic inequalities among women receiving intrauterine transfusions.

Maintaining adequate donations and a sustainable blood supply: Lessons learned

Background

The availability of a safe blood supply is a key component of transfusion medicine. A decade of decreased blood use, decreased payment for products, and a dwindling donor base have placed the sustainability of the US blood supply at risk.

Study Design and Methods

A literature review was performed for blood center (BC) and hospital disaster management, chronically transfusion‐dependent diseases, and appropriate use of group O‐negative red blood cells (RBCs), and the Choosing Wisely campaign. The aim was to identify current practice and to make recommendations for BC and hospital actions.

Results

While BCs are better prepared to handle disasters than after the 9/11 attacks, messaging to the public remains difficult, as donors often do not realize that blood transfused during a disaster was likely collected before the event. BCs and transfusion services should participate in drafting disaster response plans. Hospitals should maintain inventories adequate for patients in the event supply is disrupted. Providing specialty products for transfusion‐dependent patients can strain collections, lead to increased use of group O RBCs, and create logistical inventory challenges for hospitals. The AABB Choosing Wisely initiative addresses overuse of blood components to optimally use this precious resource. Group O‐negative RBCs should be transfused only to patients who truly need them.

Conclusions

Collecting and maintaining a blood supply robust enough to handle disasters and transfusion‐dependent patients in need of specialty products is challenging. Collaboration of all parties should help to optimize resources, ensure appropriate collections, improve patient care, and ultimately result in a robust, sustainable blood supply.

How do I see the production of engineered blood cells available for transfusion?

The in vitro production of red blood cells and platelets is a groundbreaking technology that can-when optimized-surrogate for donated blood cells, in total or in part. Here we discuss questions that may arise when the technology is available, relative to safety issues (comprising both quantitative and qualitative parameters) and to ethics, an item often forgotten in the debates so far.

Utilising red cell antigen genotyping and serological phenotyping in sickle cell disease patients to risk-stratify patients for alloimmunisation risk

BACKGROUND

Alloimmunisation and haemolytic transfusion reactions (HTRs) can occur in patients with sickle cell disease (SCD) despite providing phenotype-matched red blood cell (RBC) transfusions. Variant RBC antigen gene alleles/polymorphisms can lead to discrepancies in serological phenotyping. We evaluated differences between RBC antigen genotyping and phenotyping methods and retrospectively assessed if partial antigen expression may lead to increased risk of alloimmunisation and HTRs in SCD patients at a tertiary centre in Canada.

METHODS

RBC antigen phenotyping and genotyping were performed by a reference laboratory on consenting SCD patients. Patient demographic, clinical and transfusion-related data were obtained from a local transfusion registry and chart review after research ethics board approval.

RESULTS

A total of 106 SCD patients were enrolled, and 91% (n = 96) showed additional clinically relevant genotyping information when compared to serological phenotyping alone. FY*02N.01 (FY*B GATA-1) (n = 95; 90%) and RH variant alleles (n = 52, 49%; majority accompanied by FY*02N.01) were common, the latter with putative partial antigen expression in 25 patients. Variability in genotype-phenotype antigen prediction occurred mostly in the Rh system, notably with the e antigen (kappa: 0.17). Fifteen (14.2%) patients had a history of alloimmunisation, with five having HTR documented; no differences in clinical outcomes were found in patients with partial antigen expression. Genotype/extended-phenotype matching strategies may have prevented alloimmunisation events.

CONCLUSION

We show a high frequency of variant alleles/polymorphisms in the SCD population, where genotyping may complement serological phenotyping. Genotyping SCD patients before transfusion may prevent alloimmunisation and HTRs, and knowledge of the FY*02N.01 variant allele increases feasibility of finding compatible blood.

Distribution of Red Blood Cell Alloantibodies Among Transfusion-Dependent β-Thalassemia Patients in Different Population of Iran: Effect of Ethnicity

The best approach for prevention of alloimmunization in β-thalassemia (β-thal) patients is perfect matching of all red blood cell (RBC) antigens associated with clinically significant antibodies, but this is expensive and may limit the blood supply. Knowing the most common alloantibodies in transfusion-dependent β-thal patients make it possible to establish more cost-effective matching strategies for high-risk antigens. With this in mind, we intended to determine the most common alloantibodies in different parts of Iran. A total of 480 alloimmunized β-thal major (β-TM) patients who were referred to the Tehran Adult Thalassemia Clinic in Tehran, Iran from all provinces between 2015 and 2017, were included in this study. Antibody screening was performed on the fresh serum of all patients. Subsequently, the specification of antibodies was identified using a panel of recognized blood group antigens. Anti-K was the most common alloantibody detected in β-TM patients in all regions of Iran. The prevalence of this antibody reached to 37.7% in the western area, but in southeastern region, anti-E was predominant. Interestingly, the rare alloantibody anti-Kp^a was detected with a high prevalence in the western region. The antibodies against E and D antigens were also encountered with high prevalence in most regions of the country. The present study demonstrated the distribution of alloantibodies in alloimmunized transfusion-dependent β-thal patients from diverse ethnic and racial backgrounds of the Iranian population. The results of this study can be used as a basis to establish cost-effective RBC phenotyping and matching strategies for high-risk antigens in donors and chronic transfusion recipients in different regions of Iran.

Towards a Regional Registry of Extended Typed Blood Donors: Molecular Typing for Blood Group, Platelet and Granulocyte Antigens

BACKGROUND

The provision of compatible blood products to patients is the most essential task of transfusion medicine. Besides ABO and Rh, a number of additional blood group antigens often have to be considered for the blood supply of immunized or chronically transfused patients. It also applies for platelet antigens (HPA) and neutrophil antigens (HNA) for patients receiving platelet or granulocyte concentrates. Here, we describe the molecular screening for a number of blood group, HPA, and HNA alleles. Based on the screening results we are building up a regional blood donor registry to provide extended matched blood products on demand.

METHODS

We developed and validated TaqMan™ PCR and PCR-SSP methods for genetic markers defining 37 clinically relevant blood group antigens (beyond ABO and Rh), 10 HPA, and 11 HNA. Furthermore, we describe a feasible method for fast molecular screening of the HNA-2null phenotype. All data were statistically evaluated regarding genotype distribution. Allele frequencies were compared to ExAC data from non-Finnish Europeans.

RESULTS

Up to now more than 2,000 non-selected regular blood donors in south-west Germany have been screened for blood group, HPA, and HNA alleles. The screening results were confirmed by serology and PCR-SSP methods for selected numbers of samples. The allele frequencies were similar to non-finnish Europeans in the ExAC database except for the alleles encoding the S, HPA-3b and HNA-4b antigens, with significantly lower prevalence in our cohort, as well as the LU14 and the HNA-3b antigens, with a higher frequency compared to the ExAC data. We identified 71 donors with rare blood groups such as Lu(a+b-), Kp(a+b-), Fy(a-b-) and Vel-, and 169 donors with less prevalent HPA or HNA types.

CONCLUSION

Molecular screening for blood group alleles by using TaqMan™ PCR is an effective and reliable high-throughput method for establishing a rare donor registry.