RBC alloantibody specificity and antigen potency in Olmsted County, Minnesota

Prevalence of red blood cell alloantibodies among blood donors in the French Military Blood Institute: A 10-year retrospective study

BACKGROUND AND OBJECTIVES

Screening for red blood cell alloantibodies (RBC-Ab) is a critical step in ensuring blood transfusion safety performed by blood donation screening laboratories. We aim to evaluate the prevalence of the RBC-Ab among healthy blood donors.

MATERIALS AND METHODS

Antibody screening of serum of all voluntary blood donors was performed as a routine immune-haematological procedure by a solid-phase method on a fully automated immunohaematology analyser. Positive sera were further investigated to identify the specificity of RBC-Ab by a commercially available red cell panel.

RESULTS

Between January 2012 and December 2021, a total of 212,218 donations were screened for the presence of RBC-Ab, 74% from male donors (n = 157,898) and 26% from female donors (n = 54,320). Mean age at donation time was 32 ± 12 years. A total of 1007 donations were screened positive (0.47%), and 131 were confirmed positive for alloantibodies in their serum, yielding a prevalence of 0.06% (95% confidence interval: 0.05-0.07). Most frequent alloantibodies identified were of RH blood group system (64%), followed by anti-MNS (19%), anti-Kidd and Lewis (6% each) and anti-KEL (4%). The results showed a statistically higher prevalence of alloantibodies in women than men. Our results showed a lower prevalence as compared to the available data, which might be related to our study population.

CONCLUSION

The prevalence of positive antibody screening in healthy donors in this study was found to be 0.47%, while the prevalence of alloantibodies was 0.06%. The most common alloantibodies were anti-RH1 (25%) and anti-RH3 (24%).

Implementation of a molecular genotyping protocol for patients with warm autoantibodies

BACKGROUND

Warm autoantibodies (WAAs) cause delays and additional expenses while determining suitable products when using a traditional protocol (TP). In 2013, Carter BloodCare Immunohematology Reference Laboratory (IRL) introduced a molecular protocol (MP) for patients with WAAs.

STUDY DESIGN AND METHODS

Retrospective review of records for samples referred to the IRL from November 2004 to September 2020, was performed. Referrals, alloantibody(ies), gender, and age were recorded. Additionally, the count of common clinically significant antigens needed for phenotypically matched red blood cells (RBCs) were recorded for patients in MP. To further analyze charges and time spent testing patients with WAAs, 300 patients were selected.

RESULTS

Analysis of average charges to the referring hospital and time spent testing in the IRL determined savings at two or more referrals. Overall, 219 of 300 (73%) of patients in the study met or exceeded the number of referrals. Further analysis shows that while the population of patients with WAA (n = 300) shared similar demographics, there was a statistically significant difference between the average time testing patients in TP (M = 264.18, SD = 15.06) and MP (M = 156.00, SD = 90.37), t(157) = 14.46, p < .001, 95% confidence interval [CI] (93.41-122.97). Additionally, the assumption that each patient received two RBCs per referral provided no statistically significant difference between average charges to the hospitals of patients in TP (M = 1222.58, SD = 165.69) and MP (M = 1269.78, SD = 433.52), t(192) = -1.25, p = .214, 95% CI (-121.95-27.54).

CONCLUSION

The MP has been effective in saving time spent testing patients with WAAs, which benefits referring hospitals, patients, and IRLs. Charges for prophylactic phenotypically matched blood were negligible and a MP would alleviate some of the current laboratory difficulties while providing safe products to patients.

Frequency and Underlying Causes of Alloimmunization Against Red Blood Cell Antigens in Patients Referred to the Blood Bank of the Tertiary Referral Hospital of Tehran from 2018 to 2020

BACKGROUND

Alloimmunization against blood group antigens is an important non-infectious complication of blood transfusion, and early detection of these alloantibodies by antibody screening before transfusion is crucial. Identifying which underlying factors will affect the occurrence of alloimmunization will be necessary to manage this event as accurately as possible. We aimed to assess the prevalence rate and main determinants of RBC alloimmunization among patients referred to a large referral blood bank in Iran.

METHODS

This retrospective cross-sectional study was conducted on all patients referred to a blood bank at Imam Khomeini Hospital between October 2018 and September 2020. Information was collected by referring to the archives of the hospital information system as well as the documents recorded at the blood bank ward and reviewed by two pathologists and completed documents.

RESULTS

In total, 39270 cases were cross-matched. Accordingly, the frequency of alloimmunization cases was equal to 220 cases, which indicated a prevalence of 0.56%. The most common alloantibodies were anti-K (43.2%, 95% CI: 36.8‒49.5), anti-E (34%, 95% CI: 27.7‒40.5), and anti-C (16.3%, 95% CI: 11.4‒21.4). Among patients with positive alloimmunization, the most common blood groups were blood group B (34.6%), followed by blood group A (34.1%). Most of these patients were Rh-positive (77.3%). In patients with positive alloimmunization, the frequency of hemoglobinopathy was estimated to be 37.7%. Frequent blood transfusions were found in 42.2%, a history of malignancy in 17.3%, graft history in 11.3%, and a history of pregnancy in 35.0%.

CONCLUSION

Alloimmunization was more prevalent and more predictable among patients with hemoglobinopathies and those receiving recurrent transfusions. Therefore, a history of repeated blood transfusions should be regarded as a risk factor contributing to alloimmunization.

Anti-JMH alloantibody in inherited JMH-negative patients leads to immunogenic destruction of JMH-positive RBCs

The clinical significance of the specific anti-John Milton Hagen (JMH) alloantibody in inherited JMH-negative patients remains unclear. During clinical blood transfusion, it is often classified as an anti-JMH autoantibody in acquired JMH-negative patients, which might further lead to the occurrence of haemolysis events. In this study, we found that the proportion of inherited JMH-negative people in the Guangzhou population was 0.41%, based on the study of 243 blood samples by flow cytometry. Gene sequencing analysis revealed two novel variants located in exon 11 (c.1348G>A, p.Ala449Thr) and exon 14 (c.1989G>T, p.Leu663Phe). Specific antigen presentation showed that JMH-positive RBCs (red blood cells) could be internalized by SEMA7A^-/- dendritic cells (DCs) and that SEMA7A^-/- DCs activated by the semaphorin 7a (Sema7a) protein or JMH-positive erythrocytes further induced activation of CD4⁺ T cells to secrete interferon (IFN)-γ. Transfusion of JMH-positive RBCs could lead to the production of the specific anti-JMH alloantibody in Sema7a knock-out (KO) C57 mice. After erythrocyte sensitization, complement C3 was specifically fixed, causing the destruction of JMH-positive erythrocytes. The anti-JMH alloantibody caused immunological destruction of JMH-positive erythrocytes and promoted the clearance of JMH-positive RBCs. We should be cautious when making conclusions about the clinical significance of the anti-JMH alloantibody.

Reduction of anti-K-mediated hemolytic disease of newborns after the introduction of a matched transfusion policy: A nation-wide policy change evaluation study in the Netherlands

BACKGROUND

During pregnancy, maternal red blood cell (RBC) antibodies can lead to life-threatening fetal hemolysis and anemia. Women can become immunized by a pregnancy or an unmatched transfusion. Our aim was to quantify the effect of a nationwide K-matched transfusion policy for women of childbearing age potential to prevent K-immunization in pregnancy.

STUDY DESIGN AND METHODS

In this nation-wide policy change evaluation study we determined the occurrence of RBC antibodies before and after introduction of a K-matched transfusion policy and evaluated the cause K alloimmunization 10 years after introduction of this measure. K-matched transfusion for females under 45 years of age is advised in the Dutch transfusion guideline since 2004. We used laboratory data from pregnancies with RBC antibodies identified in the period 1999-2018 obtained as part of a population-based screening program in the Netherlands.

RESULTS

Tests of 36 286 pregnancies produced a positive antibody screening result which concerned anti-K in 1550 pregnancies. The occurrence of anti-K decreased from 67.9 to 20.2 per 100 000 pregnancies. The relative risk reduction was 0.70 which largely exceeded the relative risk reduction of 0.27 for antibodies against RBC antigens for which no preventive matching is required. The number of pregnancies at risk for anti-K-mediated disease decreased from 9.7 to 4.2 per 100 000 pregnancies.

CONCLUSIONS

A K-matched transfusion policy is associated with a major decrease in a number of pregnant women with anti-K and pregnancies at risk for anti-K-mediated disease. A relatively simple measure is now shown to impact prevention of hemolytic disease in the fetus and newborn.

Prevalence of Red Blood Cell Alloimmunization among Transfused Chronic Kidney Disease Patients in Hospital Universiti Sains Malaysia

Objectives

Red blood cell (RBC) immunization is a common complication in blood transfusion recipients. Patients with chronic kidney disease (CKD) eventually develop anemia, which is multifactorial, and requires regular blood transfusions, which exposes patients to the development of RBC antibodies. We sought to determine the prevalence and specificity patterns of RBC immunization and its risk factors among transfused CKD patients.

Methods

We conducted a cross-sectional study over one year from January to December 2018 in the Transfusion Medicine Unit, Hospital Universiti Sains Malaysia. A total of 249 samples were recruited from CKD patients who received a blood transfusion (at least one-pint), which only match for ABO and Rh(D) antigen. The serum was screened for the presence of the RBC antibody using the gel agglutination technique (Diamed gel cards). Samples with positive antibody screening were subjected to antibody identification.

Results

Of the 249 transfused CKD patients, 31 (12.4%) developed RBC immunization. Thirty (12%) were alloimmunized, and one (0.4%) was autoimmunized. Anti-Mia was the most common antibody (n = 14, 46.7%) among alloantibodies, followed by anti-E (n = 7, 23.3%). There was a significant association between pregnancy history with the development of antibodies whereas, no significant association was found between sociodemographic background, stage of CKD, hemodialysis status, underlying medical illness, and number of packed cell transfusions with the development of RBC antibodies.

Conclusions

One-eighth of our patient cohort had RBC alloimmunization, and the risk was increased in patients with a history of pregnancy. We propose Rhesus RBC phenotyping and to supply blood match Rhesus antigen in CKD patients, especially patients of reproductive age.

Erythrocyte Alloimmunity and Genetic Variance: Results from the Collaborative Study of Alloimmunity to Antigen Diversity in Asian Populations (All ADP)

As an East-Asian international study, we evaluated erythrocyte alloimmunity by gender and history of transfusion or pregnancy. In total, data from more than 1,826,000 patients were analyzed, from whom 26,170 irregular erythrocyte antibodies were detected in 22,653 cases. Antibody frequencies in these cases were as follows: anti-E, 26.8%; anti-Le^a, 20.0%; anti-P1, 7.1%; anti-M, 6.4%; anti-Mi^a, 5.6%; anti-c + E, 5.6%; anti-Le^b, 4.6%; anti-D, 2.8%; anti-Fy^b, 2.6%; anti-Le^a+Le^b, 2.5%; anti-Di^a, 2.0%; and others. For pregnant patients, anti-D (12.7%) was statistically more frequent. For transfused patients, anti-E (37.3%), anti-c + E (9.5%), anti-C + e (3.3%) and anti-Jk^a (3.1%) were significantly more frequent.

Retrospective Study on Prevalence, Specificity, Sex, and Age Distribution of Alloimmunization in Two General Hospitals in Athens

Objective:

Blood transfusion is a common lifesaving treatment but it is often complicated with alloimmunization. Previously studies in Greece have concentrated on alloimmunization in multiply transfused thalassemic patients or antenatal women. However, the relative frequency of red blood cell (RBC) alloantibodies in the general patient population has not been studied so far. The aim of the present retrospective study was to estimate the prevalence and specificity of RBC alloantibodies in a large cohort of patients in two general hospitals and their association with age, sex, and the patients’ clinic of hospitalization.

Materials and Methods:

Data from 2012 to 2016 from the “Sismanogleio” and “Thriasio” general hospitals in Athens, Greece, were studied retrospectively. Statistical analysis was performed with SAS for Windows 9.4.

Results:

Six hundred twenty-six patients (626/53800, 1.16%) were alloimmunized for one or more alloantibodies. The mean age was 67.99±17.56 years. Most antibodies were found in women [62.66% (438/699) in women vs. 37.34% (261/699) in men (p=0.0007)], while the vast majority of antibodies (66.81%) were found in patients aged 61-90. The most frequent antibody was anti-Kell (26.61%), followed by anti-E (16.02%), anti-D (15.02%), anti-Jka (5.87%), and anti-M (5.72%). Anti-C (81.48%, n=27) and anti-Cw (54.17%, n=24) tended to be found more often in patients with multiple antibodies. Most alloimmunized cases were found in general surgery (42.65%) and internal medicine departments (38.66%).

Conclusion:

According to our results, the alloimmunization data in a general patient population in Greece were consistent with the majority of studies in the international literature. Whether a strategy at national level needs to be directed towards extending matching for the whole population or towards applying sensitive and compulsory indirect antiglobulin tests before any transfusions in order to efficiently prevent alloimmunization remains an issue of debate.

Blood group antigen and phenotype prevalence in the Korean population compared to other ethnic populations and its association with RBC alloantibody frequency

OBJECTIVES

This study aimed to analyse the allele frequency of blood group antigens in the Korean population and other ethnic populations and the association of blood group antigens with red blood cell (RBC) alloantibodies.

BACKGROUND

Blood group antigen genotyping can support patients undergoing frequent transfusions who have alloantibodies and antibodies against high-prevalence blood group antigens.

METHODS

Twenty-nine single nucleotide variations and 37 blood group antigens were tested. Samples requested for routine blood typing were collected from Jan to Apr 2016. Genotyping was performed on 145 Korean samples and was confirmed by bidirectional sequencing and serologic tests. The allele frequency data were compared with previous genotyping datasets (three datasets from Korea and one each from China, Europe, Asia, and the USA). Alloantibody frequencies and blood group antigens from the electronic medical record of 1772 cases were examined.

RESULTS

E antigen was higher in the Korean population compared to that of Asian and European populations. K, Kp^a , Fy^b and Do^a allele frequencies were lower compared to other ethnic populations. RBC alloantibodies with frequencies (%) greater than 1% from the 1772 cases were as follows: anti-E, 36·7%, anti-C, 17·7%; anti-c 7·39%; anti-M, 5·9%; anti-e, 5·2%; anti-Jk^a , 2·9%; and anti-Fy^a , 1·1%. Blood group antigens and alloantibody frequencies revealed inverse trends that did not reach statistical significance.

CONCLUSION

The allele frequency of blood group antigens assessed by high-throughput methods provided reliable and valuable information that could be used for maintaining donor pools and providing compatible blood for genotyped patients.

Prevalence and risk factors for RBC alloantibodies in blood donors in the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III)

BACKGROUND

Little information exists on red blood cell (RBC) alloimmunization in healthy US blood donors, despite the potential significance for donors themselves, blood recipients, and the blood center.

STUDY DESIGN AND METHODS

Donor/donation data were sourced from the Recipient Epidemiology and Donor Evaluation Study-III, which contains information from four US blood centers during 2012 through 2016. Multivariable logistic regression was used to assess prevalence of positive antibody screen by donor demographics, blood type, parity, and transfusion history.

RESULTS

More than 2 million units were collected from 632,378 donors, with 0.51% of donations antibody screen positive and 0.77% of donors having at least one positive antibody screen. The most common antibody specificities were D (26.4%), E (23.8%), and K (21.6%). Regression analysis indicated that increasing age, female sex, D-negative status, and history of transfusion and pregnancy were positively associated with a positive antibody screen. Prior transfusion history was most strongly associated with a positive antibody screen, with donors reporting a prior transfusion having a higher adjusted odds ratio (3.9) of having a positive antibody screen compared to donors reporting prior pregnancy (adjusted odds ratio, 2.0). Though transfusion was a more potent immune stimulus for RBC alloantibody formation than pregnancy, the sheer number of previously pregnant donors contributed to pregnancy being a risk factor for the majority of clinically significant RBC alloantibodies detected in females.

CONCLUSION

These findings on prevalence of and risk factors for RBC antibodies may have implications for future medical care of donors and for operations at blood centers.

High immunogenicity of red blood cell antigens restricted to the population of African descent in a cohort of sickle cell disease patients

BACKGROUND

Sickle cell disease (SCD) patients undergo multiple red blood cell (RBC) transfusions and are regularly exposed to low-prevalence (LP) antigens specific to individuals of African descent. This study evaluated the prevalence of antibodies against LP antigens in SCD patients and the need to identify these antibodies in everyday practice.

STUDY DESIGN AND METHODS

Plasma from 211 SCD patients was tested with RBCs expressing the following LP antigens: RH10 (V), RH20 (VS), RH23 (D^W ), RH30 (Go^a ), KEL6 (Js^a ), and MNS6 (He).

RESULTS

Nine LP antibodies were found in eight patients (3.8%): five anti-RH23, two anti-RH30, and two anti-MNS6. The exposure risk, calculated for each LP antigen, was below 3% per RBC unit, for all antigens tested. Thus, in this cohort of transfused SCD patients, the prevalence of LP antibodies was similar to that of antibodies against antigens of the FY, JK, and MNS blood group systems. These findings also reveal the occurrence of anti-RH23 in SCD patients. No anti-RH20 or anti-KEL6 were found, despite the high frequency of mismatch situations.

CONCLUSION

These results highlight the immunogenicity of these LP antigens, and the evanescence of antibodies against LP antigens. They also highlight the importance of appropriate pretransfusion testing for patients frequently transfused, who are likely to be exposed to multiple types of blood group antigens.

The prevalence, immunogenicity, and evanescence of alloantibodies to MUT and Mur antigens of GP.Mur red blood cells in a Southeast Asian patient cohort

BACKGROUND

Antibodies to Mi^a , MUT, and Mur are among the most frequently identified alloantibodies in Southeast Asia. Understanding the characteristics of these antibodies in terms of induction and evanescence would aid in optimizing methods for their detection.

STUDY DESIGN AND METHODS

Antibody testing results between the years 2013 and 2015 with relevant patient demographic data and red blood cell (RBC) transfusion history were retrieved. Cumulative alloimmunization incidence and evanescence to MUT and Mur were estimated by Kaplan-Meier analysis in relation to the number of RBC units transfused and time.

RESULTS

Of 70,543 selected patients, 6186 nonalloimmunized subjects with available antibody testing results posttransfusion were identified. Cumulative alloimmunization incidence for MUT increased from 0.12% (95% confidence interval [CI], 0.03-0.21) to 0.63% (95% CI, 0.25-1.01), while for Mur it increased from 0.04% (95% CI, 0-0.09) to 0.42% (95% CI, 0.05-0.79) when a patient was transfused 2 RBC units as compared to 12. Both antibodies had high evanescence rates and at 1 year, anti-MUT and -Mur will be detected in only 45% (95% CI, 35%-57%) and 27% (95% CI, 17%-43%), respectively, of previously positive patients. MUT and Mur immunogenicity was estimated to be 1.7 and 1.2 times higher than E when their rate of evanescence was taken into account.

CONCLUSION

Antibodies to MUT and Mur develop following multiple RBC exposures. Immunogenicity of MUT/Mur and evanescence rates of the corresponding antibodies is higher compared to anti-E. Appropriate selection of antibody screening cells is needed in view of the high prevalence, immunogenicity, and evanescence of the antibodies.

RBC alloantibody prevalence and specificity in a Western Norwegian tertiary hospital

BACKGROUND AND OBJECTIVE

Although several studies focus on red blood cell (RBC) alloantibody distribution in selected patient populations, few address the specificity and frequency in all relevant groups. This study reports alloantibody frequency, distribution and the relationship to age and gender in blood donors, pregnant women and potential recipients of blood products.

METHODS

This historical cohort study included 55 462 consecutive antibody screening tests from a tertiary Western Norwegian Hospital. Descriptive statistics were performed, and the results were compared with the literature.

RESULTS

The detection and immunisation frequency for the whole cohort were 0·39 and 0·51%, respectively, whereas the RBC alloantibody prevalence was 0·73%. The most frequent RBC alloantibodies were anti-E (20·1%), anti-M (18·7%), anti-K (9·8%), anti-D (8·9%) and anti-Fy(a) (7·0%). In pregnant women, the most frequent RBC alloantibodies were anti-M, anti-D and anti-Le(a) (20·8, 18·9 and 18·9%, respectively), whereas there was no anti-K detected. Anti-E and anti-M were the dominating RBC alloantibodies in the pre-transfusion testing of in-hospital patients (24·1 and 17·1%, respectively). Eighteen (9·2%) persons in the total cohort had two RBC alloantibodies, six persons had three alloantibodies, and two persons had four alloantibodies. Rh and K typing to prevent future immunisations was only performed in 21·0% of the individuals who presented with a new alloantibody; despite that, 50·5% of the detected alloantibodies had such specificities.

CONCLUSIONS

The immunisation frequency and the level of anti-K are low compared to national and international studies. Rh and K phenotype-matched blood transfusions might be a feasible future strategy to further decrease RBC alloantibodies.

Prevalence of irregular red cell antibody in healthy blood donors attending a tertiary care hospital in North India

BACKGROUND:

Alloantibodies may be detected in blood donors who have either been transfused previously or female donors with previous obstetric events. These antibodies can occasionally cause severe transfusion reaction, if a large amount of plasma or whole blood is transfused, as in massive transfusions and pediatric patients.

AIMS:

The present study aims to assess the prevalence of red cell antibodies in healthy blood donors at a tertiary care hospital-based blood bank in India.

MATERIALS AND METHODS:

A total of 82,153 donor samples were screened for irregular red cell antibodies between January 2012 and December 2015 at the Department of Transfusion Medicine, Indraprastha Apollo Hospitals, New Delhi. Antibody screening was performed by solid phase method using Immucor Capture–R ready screen (pooled cells) on fully automated immunohematology analyzer Galileo Neo (Immucor Inc., Norcross, GA, USA). Positive tests were further confirmed using Capture-R ready screen (4 cell panel). Advanced investigations to identify the antibody/ies were performed on confirmed positive samples. Antibody identification was conducted using various cell panels (Immucor Capture-R Ready-ID, Panocell-10, Ficin Treated). An advanced technique such as adsorption and elution was performed as per requirement.

RESULTS:

Screening with pooled cells and 4 cell panel was positive in 227 donors (0.27%), 150 of these donors had autoantibodies, 1 had autoantibodies with underlying alloantibody anti-Jk^a (0.001%), and 76 had alloantibodies (0.09%) alone in their plasma. Anti-M was the most common antibody (43 donors) identified, followed by anti-D (21 donors). Anti-N was detected in 4; anti-Jk^a, anti-C, and anti-E in two donors each followed by anti-P1 and anti-Le^b in 1 donor.

CONCLUSION:

Antibodies against red cells can be present in healthy donors detection of which is important in providing safe blood to the patient. The prevalence of red blood cell antibody in healthy donors in this study was found to be 0.27%, while the prevalence of alloantibodies was 0.09%. The majority of alloantibodies were anti-M (56.57%) and anti-D (27.63%).

Erythrocyte Alloimmunization and Autoimmunization among Blood Donors and Recipients visiting a Tertiary Care Hospital

INTRODUCTION

The ultimate aim of pretransfusion testing is the acceptable survival of donor red cells in recipient's body and antibody detection plays a critical role in achieving the same. The cornerstone of antibody detection method is detecting an unexpected antibody as against the expected antibodies of ABO blood group system. Autoantibodies can also interfere with the detection of clinically significant alloantibodies.

AIM

To study the frequency of alloantibodies and autoantibodies in the healthy blood donors and patient population visiting our hospital.

MATERIALS AND METHODS

The Column Agglutination Technology (CAT) was used for ABO RhD blood grouping, Direct Antiglobulin Test (DAT), Autocontrol (AC), Indirect Antiglobulin Test (IAT) and red cell antibody screening and the unexpected reactions in any of these tests were recorded for further evaluation. Ethylene Diamine Tetra Acetic Acid (EDTA) blood samples were used for all these tests for both blood donors and admitted patients. The CAT was exercised for the blood grouping (using ABD-Reverse Diluent cassettes) and antibody screening (using 0.8% Surgiscreen, Ortho Clinical Diagnostics Limited, USA and Low Ionic Strength Saline Ortho BLISS with AHG cassettes) on the automated immunohaematology platform ORTHO AutoVue^® Innova system (Ortho Clinical Diagnostics Limited, USA).

RESULTS

Among all blood donors (n=6350), seven (0.11%) donors had showed unexpected reaction. Of these, four had positive antibody screen (three having naturally occuring antibodies 2=anti-M, 1=anti-Le^a and 1=inconclusive) and the other three had positive DAT. Of all the patient samples (n=6136) screened for irregular red cell antibodies, four (0.06%) patients were found to have unexpected reaction revealing one (0.02%) with anti-M antibody and the other three (0.05%) had autoantibodies in their serum.

CONCLUSION

The combined prevalence for both blood donor and recipient population (n=12,486) was found to be 0.11% at our center. The alloimmunisation among patient population was found to be lower than many other studies worldwide as our hospital does not cater to multitransfused or transfusion dependant patients with haematological disorders and majorly elective surgery patients with no history of previous blood transfusions visit our hospital.

Association of HLA-DRB1 and HLA-DQB1 with red-blood-cell alloimmunization in the Czech population

BACKGROUND AND OBJECTIVES

Alloimmune antibodies against red-blood-cell (RBC) antigens induced in susceptible individuals (responders) by transfusion, pregnancy or transplantation may have serious clinical consequences. The aim of this study was to investigate association of alloimmunization against selected RBC antigens with HLA-Class II.

MATERIALS AND METHODS

A total of 230 responders (106 monoresponders and 124 multiresponders) were enrolled into the study. HLA-DRB1 and HLA-DQB1 variants were determined by PCR-SSO and their frequencies compared between the patients (patient subgroups) and 375 ethnically and regionally matched controls.

RESULTS

Development of multiple RBC antibodies was associated with HLA-DRB1*15 and HLA-DQB1*06 allelic groups in the patients, with the relationship being particularly apparent in those with anti-C+D antibodies. Furthermore, DRB1*13 and DQB1*06 were more frequent in multiresponders with anti-E+c antibodies and DRB1*03 and DQB1*02 in those with anti-E+Cw.

CONCLUSION

For the first time, we confirmed the association of HLA-DRB1*15 with RBC antibody multiresponder status and found HLA-Class II associations for three frequent RBC antibody combinations. Our data support the concept that HLA restriction plays an important role in the response to RBC alloantigens.

Can the interval between antibody identifications be increased for alloimmunized patients?

BACKGROUND

New alloantibody formation is unpredictable in patients who have been previously alloimmunized. Pretransfusion testing is designed to detect these antibodies while antibody identification (ABI) techniques are designed to identify the specificity of the antibody. Pretransfusion testing intervals are prescribed by regulatory and accrediting agencies, intervals for ABI in alloimmunized patients are not. Our institution evaluated the safety of increasing the interval from every 72 hours to 14 days. The current 72-hour interval was chosen at our institution to align with AABB Standard 5.14.3.2, which requires a pretransfusion specimen drawn within 3 days of the scheduled transfusion for potentially immunized patients.

STUDY DESIGN AND METHODS

Over 2 years, all ABI entries in the laboratory information system were screened. All cases of alloimmunized patients with an additional antibody specificity that developed within 14 days of a previous ABI were reviewed and confirmed by four transfusion medicine physicians.

RESULTS

Initially, 8948 entries were screened. Thirty patients were identified to have formed 33 newly identified clinically significant alloantibodies within 14 days. After further categorization, only 13 antibodies (0.15% of all ABIs, 0.47% of alloimmunized patients examined) were deemed to be newly formed clinically significant antibodies that would have led to a change in transfusion practice.

CONCLUSION

Retrospective analysis of ABI results over a 2-year period revealed that 0.47% of previously alloimmunized patients that have samples for pretransfusion testing develop a new clinically significant alloantibody in 14 days or less. While there would be significant resource advantages to increasing the duration between repeat ABI, it does not outweigh the risk of a potential hemolytic transfusion reaction.

Frequency and specificity of red blood cell alloimmunization in chilean transfused patients

BACKGROUND

Alloimmunization is an adverse effect of blood transfusions. In Chile, alloimmunization frequency is not established, and for this reason the aim of this study was to investigate the prevalence and specificity of red blood cell (RBC) alloantibodies in Chilean transfused subjects.

METHODS

Records from 4,716 multi-transfused patients were analyzed. In these patients, antibody screening was carried out prior to cross-matching with a commercially available two-cell panel by the microcolum gel test, and samples with a positive screen were analyzed for the specificity of the alloantibody with a 16-cell identification panel.

RESULTS

The incidence of RBC alloimmunization in transfused patients was 1.02% (48/4,716) with a higher prevalence in women (40/48). We detected 52 antibodies, the most frequent specificities identified were anti-E (30.8%), anti-K (26.9%), anti-D (7.7%), and anti-Fy(a) (5.8%). The highest incidence of alloantibodies was observed in cancer and gastroenterology patients.

CONCLUSION

The data demonstrated a low alloimmunization frequency in Chilean transfused patients, principally associated with antibodies anti-E, anti-K, anti-D, and anti-Fy(a).

The Influence of Clinical and Biological Factors on Transfusion-Associated Non-ABO Antigen Alloimmunization: Responders, Hyper-Responders, and Non-Responders

In the context of transfusion medicine, alloimmunization most often refers to the development of antibodies to non-ABO red blood cell (RBC) antigens following pregnancy, transfusion, or transplantation. The development of RBC alloantibodies can have important clinical consequences, particularly in patients who require chronic transfusions. It has been suggested that alloimmunization is more common in some clinical circumstances and patient populations than in others. As such, individuals that develop alloantibodies are frequently referred to as 'responders' in the medical literature. In contrast, individuals that do not develop alloantibodies despite repeated exposures to non-self blood group antigens have been referred to as 'non-responders'. The purpose of this article is to review the phenomenon of RBC alloimmunization in the context of responders and non-responders to: i) establish a basic framework for alloimmunization as reported across several diverse patient populations; ii) more fully explore literature reports which support the concept of responders/non-responders regarding blood group antigen alloimmunization; iii) summarize the mechanisms that have been shown to predispose an individual to alloimmunization to determine how these factors may differentiate 'responders' from 'non-responders'; and iv) briefly discuss some practical approaches to prevent alloimmunization in patients who may be prone to alloantibody development.

Responder individuality in red blood cell alloimmunization

Many different factors influence the propensity of transfusion recipients and pregnant women to form red blood cell alloantibodies (RBCA). RBCA may cause hemolytic transfusion reactions, hemolytic disease of the fetus and newborn and may be a complication in transplantation medicine. Antigenic differences between responder and foreign erythrocytes may lead to such an immune answer, in part with suspected specific HLA class II associations. Biochemical and conformational characteristics of red blood cell (RBC) antigens, their dose (number of transfusions and pregnancies, absolute number of antigens per RBC) and the mode of exposure impact on RBCA rates. In addition, individual circumstances determine the risk to form RBCA. Responder individuality in terms of age, sex, severity of underlying disease, disease- or therapy-induced immunosuppression and inflammation are discussed with respect to influencing RBC alloimmunization. For particular high-risk patients, extended phenotype matching of transfusion and recipient efficiently decreases RBCA induction and associated clinical risks.

Prevalence of irregular red blood cell antibodies among healthy blood donors in Delhi population

OBJECTIVES

To evaluate the prevalence of the anti-red blood cell antibodies among healthy blood donors.

MATERIAL AND METHODS

Antibody screening of all voluntary blood donor serum was performed as routine immunohematological procedure. Positive sera were further investigated to identify the specificity of irregular erythrocyte antibody by commercially available red cell panel (ID-Dia Panel, Diamed-ID Microtyping System).

RESULT

A total of 47,450 donors were screened for the presence of irregular erythrocyte antibodies. A total of forty-six donors showed presence of alloantibodies in their serum (46/47,450%, 0.09%), yielding a prevalence of 0.09%. Most frequent alloantibodies identified were of MNS blood group system. The results showed statistically a higher prevalence of RBC alloantibodies in females than in males.

CONCLUSION

Screening for presence of alloantibodies in donor blood is important to provide compatible blood products and to avoid transfusion reactions.

Screening of blood donors for erythrocyte alloantibodies

OBJECTIVE

To assess the prevalence of the anti-red blood cell antibodies in the donor population of Delhi.

METHODS

This prospective study was conducted in Regional Blood Transfusion Centre (RBTC), Lady Hardinge Medical College (LHMC) and associated hospitals from March 2010 to March 2011. Antibody screening of all donor serum/plasma was performed as routine immunohaematological procedure. Any positive sera were further investigated to identify the specificity of irregular erythrocyte antibody by commercially available red cell panel (ID-Dia Panel, Diamed-ID Microtyping System). The titres and thermal amplitude of the identified antibodies were evaluated.

RESULTS

A total of 7756 donors were screened, of which 7648 donors were males (98.6%) and 108 were females (1.4%). The maximum number of donors belonged to age group of 26-30 years. A total of four donors showed presence of alloantibodies in their serum (0.05%). On antibody identification, two of them were anti-C, one was anti-Lewis(a) antibody and one was autoantibody.

DISCUSSION

This study was conducted to highlight the significance of detecting irregular erythrocyte antibodies in healthy donors.

WITHDRAWN: The frequency of RBC alloantibodies in Chinese surgical patients

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.transci.2012.07.013. The duplicate article has therefore been withdrawn.

Frequency of RBC Alloantibodies in Chinese Surgical Patients

BACKGROUND: The aim of this study was to evaluate the frequency of red blood cell (RBC) alloantibodies in surgical patients. METHODS: Blood samples of 18,980 Chinese surgical patients were collected and tested between January 2009 and September 2010. For patients with RBC alloantibodies, sequences of antibodies were identified with the DiaMed Asia antibody screening system. Data regarding sex, age, transfusion history, pregnancy history, and alloantibody specificity were collected. RESULTS: 39 alloantibodies were identified from 18,980 samples, yielding a prevalence of 0.21%. The most frequently identified alloantibodies were Rhesus system antibodies (28/39, 71.8%), including anti-E (17/39; 1 anti-E accompanied by anti-Fy(b)), anti-c (5/39), anti-cE (2/39), anti-C(w) (1/39), anti-D (1/39), and anti-e (1/39). Other antibodies included anti-M (5/39), anti-Le(a) (2/39), anti-Le(b) (1/39), anti-K+S (1/39), anti-JK(a) (1/39), and anti-JS(a) (1/39). The frequency of alloantibodies was greater in females than in males (31 vs. 8). CONCLUSION: The results show a higher prevalence of RBC alloantibodies in females than in males. Anti-E was the most common alloantibody identified in this Chinese surgical population and was also more frequent in females compared to males.

High-throughput multiplex PCR genotyping for 35 red blood cell antigens in blood donors

BACKGROUND AND OBJECTIVES

One to two per cent of patients in need of red cell transfusion carry irregular antibodies to red blood cell (RBC) antigens and have to be supplied with specially selected blood units. To be able to respond to those requests, blood centres have to screen a significant number of donors for a variety of antigens serologically, which is a costly and through the shortage of reagents, also limited procedure. To make this procedure more efficient, the Austrian Red Cross has developed a genotyping assay as an alternative approach for high throughput RBC typing.

MATERIALS AND METHODS

A multiplex polymerase chain reaction (PCR) assay was designed for typing 35 RBC antigens in six reaction mixes. The assay includes both common as well as high-frequency-alleles: MNS1, MNS2, MNS3 and MNS4; LU1, LU2, LU8 and LU14; KEL1, KEL2, KEL3, KEL4, KEL6, KEL7, KEL11, KEL17 and KEL21; FY1, FY2, FYB(WK) and FY0 (FYB(ES)); JK1 and JK2; DI1, DI2, DI3 and DI4; YT1 and YT2; DO1 and DO2; CO1 and CO2; IN1 and IN2. The assay was validated using 370 selected serologically typed samples. Subsequently 6000 individuals were screened to identify high frequency antigen (HFA)-negative donors and to facilitate the search for compatible blood for alloimmunized patients.

RESULTS

All controls showed complete concordance for the tested markers. The screening of 6000 donors revealed 57 new HFA-negative donors and the blood group database was extended by approximately 210,000 results.

CONCLUSION

The study shows that in practice, this high-throughput genotyping assay is feasible, fast and provides reliable results. Compared to serological testing, this molecular approach is also very cost-efficient.

Prevalence and specificities of red cell alloantibodies among blood recipients in the Malaysian state of Kelantan

BACKGROUND

Red blood cell (RBC) alloantibodies may be formed following exposure to RBC antigens. In most cases, the alloimmunization develops during pregnancy or from previous blood transfusions. The RBC antigens and their alloantibodies vary among different human populations and ethnic groups, and they do have a clinical significance for their adverse immunological reactions.

AIMS

This study aimed at studying the prevalence of RBC alloantibodies at the Blood Transfusion Unit of Hospital Raja Perempuan Zainab II in Kota Bharu, Malaysia.

PATIENTS AND METHODS

A cross-sectional study was performed utilizing data obtained in the years 2007 and 2008. Data of antibody screening tests from 5719 patients were examined.

RESULTS AND DISCUSSION

The overall prevalence of alloimmunization was 65 (1.13%). The majority of these had a single alloantibody (76.9%), whereas the remaining 23.1% had multiple antibodies. The anti-E antibody comprised the most common alloantibody (24.6%) followed by the anti-Lewis (a) antibodies (18.5%) and the anti-M antibody (13.8%). There were more female recipients than males.

CONCLUSIONS

It was concluded that the findings of this work have been comparable with other published works, and that the main factors associated with alloantibody formation were multiple transfusions and pregnancies. The study also emphasizes the necessity for carrying out immunohematology studies prior to every blood transfusion especially in cases that require multiple transfusions for a long period of time such as in thalassemia patients.

Prevalence and specificity of red-blood-cell antibodies in a multiethnic South and East Asian patient population and influence of using novel MUT+Mur+ kodecytes on its detection

BACKGROUND AND OBJECTIVES

Appropriate screening for irregular red-cell antibodies is essential for ensuring transfusion compatibility and for antenatal management of mothers at risk of haemolytic disease of the foetus and newborn. Screening for all relevant antibodies is, however, limited by screening cells that do not express antigens present in the patient and donor population. Technology to artificially incorporate antigens into red cells is currently available and may be an option for customizing screening cells.

MATERIALS AND METHODS

We sought to identify retrospectively the changing patterns of alloantibody prevalence in our multiethnic population on change of screening cells. Antibody screening records of 143 501 patients tested from 2004 to 2010 were retrieved and divided into two groups: period-1 (2004-2008) and period-2 (2009-2010). During period-1, standard screening cells were used while in period-2, MUT+Mur+ KODE(™) transformed red cells (kodecytes) were used.

RESULTS

Four per cent of samples tested during period-2 were positive on antibody screening compared to 3·2% in period-1. Specific antibodies, excluding anti-D, were identified in 1·66% and 1·52% of patients in period-2 and -1, respectively. When confined to antibodies of clinical significance only, period-2 showed higher alloantibody prevalence of 1·16% as compared to 0·66% in period-1. Antibodies to glycophorin variants of MNS (vMNS) were more commonly detected while antibodies to Lewis antigens declined during period-2.

CONCLUSION

  Antibodies to vMNS antigens are common in South and East Asian populations and are often missed when using standard screening cells. Use of specifically engineered screening cells to express red-cell antigens artificially is beneficial in detecting the diverse alloantibodies present in our population.

Immunogenicity of blood group antigens: a mathematical model corrected for antibody evanescence with exclusion of naturally occurring and pregnancy-related antibodies

Blood group antigen immunogenicity is a crucial factor in red blood cell alloimmunization. Previous calculated estimates of immunogenicity suffered from several key shortcomings. To address these issues we have (1) introduced a correction factor for antibody persistence rates into traditional immunogenicity calculations, (2) calculated immunogenicities only in men to eliminate pregnancy-related antibodies, and (3) excluded antibodies reactive only at room temperature to minimize the contribution of naturally occurring antibodies. With these corrections, we have calculated the immunogenicities of common blood group antigens using data collected on clinically significant alloantibodies (n = 452) in a male patient population. We observed a 3- to 5-fold increase in immunogenicity for some antigens (ie, Jka, Cw, Lua) and smaller changes in others compared with traditionally calculated estimates. In addition, we have calculated the transfusion-related immunogenicities of antigens traditionally associated with naturally occurring antibodies (eg, anti-Lea, -Leb, -M, and -P1).

Risk factors for the presence of non-rhesus D red blood cell antibodies in pregnancy

OBJECTIVE

To identify risk factors for the presence of non-rhesus D (RhD) red blood cell (RBC) antibodies in pregnancy. To generate evidence for subgroup RBC antibody screening and for primary prevention by extended matching of transfusions in women <45 years.

DESIGN

Case-control study.

SETTING

Nationwide evaluation of screening programme for non-RhD RBC antibodies.

POPULATION

CASES

consecutive pregnancies (n=900) with non-RhD immunisation identified from 1 September 2002 to 1 June 2003 and 1 October 2003 to 1 July 2004; controls (n=968): matched for obstetric caregiver and gestational age.

METHODS

Data collection from the medical records and/or from the respondents by a structured phone interview.

MAIN OUTCOME MEASURES

Significant risk factors for non-RhD immunisation in multivariate analysis.

RESULTS

Significant independent risk factors: history of RBC transfusion (OR 16.7; 95% CI: 11.4-24.6), parity (para-1 versus para-0: OR 1.3; 95% CI: 1.0-1.7; para-2 versus para-0: OR 1.4; 95% CI: 1.0-2.0; para >2 versus para-0: OR 3.2; 95% CI: 1.8-5.8), haematological disease (OR 2.1; 95% CI: 1.0-4.2), history of major surgery (OR 1.4; 95% CI: 1.1-1.8). For the clinically most important antibodies, anti-K, anti-c and other Rh-nonD-antibodies RBC transfusion was the most important risk factor, especially for anti-K (OR 96.4; 95%-CI: 56.6-164.1); 83% of the K-sensitised women had a history of RBC transfusion. Pregnancy-related risk factors were a prior male child (OR 1.7; 95% CI: 1.2-2.3) and caesarean section (OR 1.7; 95% CI: 1.1-2.7).

CONCLUSIONS

RBC transfusion is by far the most important independent risk factor for non-RhD immunisation in pregnancy, followed by parity, major surgery and haematological disease. Pregnancy-related risk factors are a prior male child and caesarean section. Subgroup screening for RBC antibodies, with exclusion of RhD-positive para-0 without clinical risk factors, is to be considered. This approach will be equally sensitive in detecting severe Haemolytic Disease of the Fetus and Newborn compared with the present RBC antibody screening programme without preselection. Primary prevention by extending preventive matching of transfusions in women younger than 45 will prevent more than 50% of pregnancy immunisations.

Does an alloimmune response to strong immunogenic red blood cell antigens enhance a response to weaker antigens?

BACKGROUND

It has been suggested that an immune response against the high immunogenic D antigen also augments the immune response to less immunogenic red blood cell (RBC) antigens. Based on the high antibody frequency, E and K antigens can also be regarded as strong immunogens. The question is whether the immunization against E and K antigens also enhances the formation of other antibody specificities. This question is in particular relevant for patients who are currently transfused with RH- and/or K-matched RBCs.

STUDY DESIGN AND METHODS

A retrospective multicenter study analyzed FY, JK, and MNS antibodies alone and in combination with anti-E and/or anti-K. Analysis was performed for primary and subsequent antibody responses.

RESULTS

In the cohort analyzed, 5016 patients possessed 5981 antibodies. Antibodies directed to multiple blood group systems were present in 606 of the 779 (78%) patients with multiple antibodies. In 88 of 1270 (6.9%) patients, FY, JK, and/or MNS antibodies appeared simultaneous with anti-E and/or anti-K during a primary antibody response after transfusion. Patients formed antibodies to antigens in the FY, JK, and MNS systems equally often as first antibodies followed by anti-E or anti-K than as second antibodies after anti-E or anti-K were already present. Patients with anti-E and/or anti-K or with antibodies to antigens in the FY, JK, and/or MNS systems equally often formed additional antibodies during a second antibody response.

CONCLUSION

An immune response against allogeneic RBC antigens defines good responders who readily form antibodies against other antigens. No support was found that the response against strong RBC antigens also enhances the formation against weaker antigens.

Association between alloantibody specificity and autoantibodies to red blood cells

BACKGROUND

Alloantibodies (ALLOs) to red blood cells (RBCs) are frequently associated with autoantibodies (AABs). An association between ALLO specificity and AABs has not yet been described.

STUDY DESIGN AND METHODS

All patients and healthy blood donors screened for RBC antibodies between 2000 and 2006 were included. The odds ratio (OR) for ALLOs in patients with AABs compared to those without AABs was correlated with the OR of general ALLO prevalence in patients with AABs (normalized OR).

RESULTS

ALLOs were found in 4,626 of 204,330 patients and healthy blood donors (2.3%). The ALLOs were associated with AABs in 413 cases (8.9%). Among the specificities, anti-S with a normalized OR of 2.9 was overrepresented. This was most evident in pregnant women who showed a normalized OR of 15.1 for anti-S and AABs. The normalized OR revealed an additional association between Rh antibodies and AABs. No association was found between ALLOs to the Kell glycoprotein, Duffy protein, Lewis, or glycophorin A (M/N) and AABs.

CONCLUSION

The majority of associated ALLOs and AABs are directed against neighboring antigens of the Rh complex and glycophorin B.

Alloimmunization to Red Cell Antigens in Liver and Multivisceral Transplant Patients

BACKGROUND

Alloimmunization to red blood cell (RBC) antigens can significantly impact transfusion support of patients undergoing solid-organ transplantation. This study evaluated the incidence of clinically significant RBC alloantibodies (abs) in 2000 consecutive adults receiving liver (OLTX), intestinal (ITX) or multivisceral (MVT) transplants.

METHODS

From January 1991 to May 2006, 2000 patients underwent OLTX (n=1892), MVT (n=74), or ITX (n=34). Blood sample for serologic investigation was submitted to the transfusion service no later than 4 hr before surgery. The presence of clinically significant RBC abs before transplant with subsequent transfusion requirements, the incidence of delayed transfusion reactions, and de novo abs after transplant were evaluated.

RESULTS

One hundred fifteen patients (5.75%) had clinically significant RBC abs before transplant, with 56.7% directed against Rh system antigens. Forty-six (40%) had multiple abs. A mean of 18 packed RBC units (U) were transfused per patient. Patients requiring >20 U (n=34) or those with multiple abs received antigen-negative units for the first 5-10 U when antibody was still present, switched to antigen-unscreened units during massive blood loss and returned to antigen-negative units for the last 5-10 U transfused. Twelve patients (0.6%) developed de novo abs posttransplant. Twenty-two (1.1%) had delayed serologic transfusion reaction. All patients were successfully managed without delay in initiation of surgery or hemolytic complications.

CONCLUSION

RBC alloimmunization can present a special challenge to solid-organ transplantation. Early serologic testing of the recipient pretransplant and prompt communication between the transfusion service and transplant team facilitates successful transfusion management of these patients.

Coexistence of autoantibodies and alloantibodies to red blood cells due to blood transfusion

BACKGROUND

Autoantibodies (AUTO) to red blood cells (RBCs) are frequently associated with alloantibodies (ALLO). The mechanism for the coexistence of these antibodies is obscure.

STUDY DESIGN AND METHODS

Between August 1998 and June 2006, all in- and outpatients of the Charité University Hospital, Berlin, with detectable AUTO were included in this study. Serologic examination was performed with standard techniques for the detection of RBC antibodies.

RESULTS

A total of 717 patients were found to have AUTO, with ALLO observed in 200 of these patients (28%). The history of antibody production could be evaluated in 98 of the 200 patients. Both AUTO and ALLO were due to RBC transfusion in 73 cases (75%) and peripheral blood progenitor cell transplantation in 6 cases (6%). Nine (9%) patients were primarily alloimmunized and subsequently developed AUTO. The remaining 10 (10%) patients were primarily autoimmunized and later developed ALLO. Only 6 of these patients had chronic idiopathic autoimmune hemolytic anemia.

CONCLUSION

The majority of AUTO associated with ALLO appears to be due to RBC transfusion that must be recognized as a major cause for autoimmunization.

Red blood cell alloantibodies after transfusion: factors influencing incidence and specificity

BACKGROUND

Alloimmunization after exposure to red cell (RBC) alloantigens depends on genetic and acquired patient-related factors, dose and route of administration, and the immunogenicity of the antigen, but exact kinetics are still unknown.

STUDY DESIGN AND METHODS

A 5-year retrospective multicenter study analyzing factors influencing the rate and specificity of RBC alloimmunization was performed, with special emphasis on the time interval between transfusion event and antibody detection. Included were clinically significant alloantibodies against the Rhesus, Kell, Duffy, Kidd, and MSs blood group systems.

RESULTS

Multivariate analysis involving 1710 immunized patients revealed that time interval between transfusion and antibody tests was strongly associated with the antibody specificity. Anti-Jk(a) and anti-Jk(b) were predominantly found in patients tested within 3 months, whereas anti-K and anti-Fy(a) were the most encountered antibodies at more than 5 years after transfusion. Of all immunized patients, new antibodies were detected within 14 days after transfusion in 299 patients (16.8%) and in 1479 patients (83.2%) after more than 14 days. Fifty percent of transfusion recipients were retested for alloimmunization because of a new transfusion indication. Eleven of 2932 patients (0.4%) retested up to 3 days after transfusion had formed new antibodies.

CONCLUSION

The time interval between transfusion and antibody test was associated with RBC antibody specificity. Because RBC antibody tests after transfusion are not routinely performed, many antibodies may (not) be detected at the time of a new transfusion event, posing the transfusion recipient at risk for transfusion delay or a (delayed) hemolytic transfusion reaction. Routine RBC antibody screening at set time intervals after transfusion would reduce these risks.

Frequency of red blood cell alloantibody in Kuwaiti population

OBJECTIVE

The aim of this study was to analyze the alloimmunization against red blood cells (RBC) among Kuwaiti population.

MATERIALS AND METHODS

Retrospective analysis of RBC alloimmunization among 179,045 Kuwaiti patients, pregnant women, and allogeneic blood donors was conducted for the period of 1992-2001. The frequency of 24 alloantibody specificities from 1,278 alloimmunized Kuwaitis was estimated.

RESULTS

The prevalence of positive antibody screen in Kuwait was 0.49%. The five most frequently identified alloantibodies were anti-D (27.3%), anti-E (18.5%), anti-K (15.6%), anti-Le(a) (8.7%), and anti-Le(b) (6.6%). Frequency of alloimmunization was greater among Kuwaiti female than male patients (3.2 F to 1 M). Anti-D (p<0.001), anti-E (p=0.05), anti-K (p=0.04) were also more frequently identified alloantibody among Kuwaiti females.

CONCLUSION

The results show higher predominance of RBC alloimmunization in females than males. Anti-D, anti-E, and anti-K were the most common clinically significant alloantibodies identified in the Kuwaiti population and were also more frequent among Kuwaiti females.