Identification des allo-anticorps seuls et associés : bilan de trois années au centre régional de transfusion sanguine de Rabat/Maroc et difficultés de prise en charge transfusionnelle

Assessment of erythrocyte alloimmunization among patients treated at a Brazilian university hospital

INTRODUCTION

Alloimmunization and transfusion reactions underscore the crucial role of precise immunohematological techniques to enhance safety in transfusion. This study aims to determine the frequency of alloimmunization in patients treated at a Brazilian university hospital, investigate demographic, clinical, and epidemiological characteristics of patients with positive irregular antibody screening, as well as to assess the frequency of erythrocyte antigens and anti-erythrocyte antibodies in the population.

MATERIALS AND METHODS

This retrospective observational study included all irregular antibody-positive patients treated at the transfusion service of Hospital de Clínicas of the Federal University of Uberlandia between January 2019 and December 2020.

RESULTS

Of the 201 irregular antibody-positive patients, alloimmunization was more common in women (64.2%) than in men (35.8%). Blood groups A (39.8%) and O (38.8%), and Rh positive samples (69.1%) predominated, and about half (48.2%) of the patients were transfused for preoperative procedures. The most frequently found clinically significant alloantibodies were anti-D (27.2%), anti-E (15.0%), and anti-Kell (11.5%). Of the patients, 30.6% had multiple antibody associations, with anti-D and anti-C being the most common combination. Erythrocyte immunophenotyping was performed for 76 patients with the most frequent antigens detected being e (100%), c (86.8%), and C (40.8%). Among the 14 pregnant women evaluated, most were multiparous, 85.7% had anti-D as the most prevalent antibody, and had the A-negative blood type (33.3%).

CONCLUSION

Alloantibody screening and identification associated with erythrocyte immunophenotyping are necessary for a better understanding of the alloimmunized population, ensuring greater safety and efficacy of transfusion therapy in the hospital setting.

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.

Red blood cell alloimmunizations in beta-thalassemia patients in Casablanca/Morocco: Prevalence and risk factors

Red blood cell alloimmunization is one of the major challenges to regular transfusions in β-thalassemic patients. In Morocco, rare studies have focused on this hemoglobinopathy.

OBJECTIVE

We aimed to study the prevalence and risk factors of red cell alloimmunization in β-thalassemic patients.

PATIENTS AND METHODS

Retrospective study during 9 years (2009-2018) was conducted on 160 β-thalassemic patients transfused regularly in pediatric department of children's hospital in Casablanca, Morocco. The main clinical, demographic and transfusional characteristics of alloimmunized and non-alloimmunized patients were compared. Red blood cells units transfused were leukodeplated and phenotypically matched for RH-KELL systems and for other systems after immunization. Screening and antibody identification were performed by gel-filtration method on BIO-RAD caseds using 3 and 11 red blood cells panels. To detect autoantibodies, autocontrol and direct antiglobulin tests were carried out using polyspecific coombs (IgG/C3d) gel cards.

RESULTS

The prevalence of alloimmunizations was 8.75% during the study period. Seventeen alloantibodies identified were directed mainly against antigens of KELL and RH systems: KEL 1 (35.29%), RH 3 (23.52%), RH1 (11.76%), Kpa (11.76%), RH2 (5.88%). Red blood cells autoantibodies had been detected in 6 of 14 (42.85%) of alloimmunized patients versus 12 of 146 (11.76%) of non-alloimmunized patients (P<0.01). Presence of autoantibodies, transfusional interval<3weeks and gender were associated with high rate of red cells alloimmunization.

CONCLUSION

This study proves the data of literature. The presence of red cell autoantibodies appears to be a major risk factors for alloimmunization in thalassemic children, and could advocate specific transfusion guidelines.