RBC alloimmunization in blood transfusion-dependent beta-thalassemia patients in southern Iran

Alloimmunization in β-Thalassemia and Sickle Cell Disease in Middle Eastern Countries: A Systemic Review

Sickle cell disease and β-thalassemia are important health problems in Middle Eastern countries. Transfusion is the cornerstone of the management in these disorders, and red blood cell alloimmunization is among the well-recognized adverse effects associated with it. We reviewed the literature on published studies on alloimmunization prevalence, its associated risk factors, and transfusion policies employed in these countries. Our review included 39 studies on thalassemia (including 9005 patients), and 19 on sickle cell disease (including 3867 patients). The mean alloimmunization prevalence rate in thalassemia was 13.0% (95% CI: 10.0-15.0%), while that in sickle cell disease was 14.0% (95% CI: 10.0 - 19.0%). The distribution of the prevalence rates showed considerable heterogeneity in both diseases. The most frequent alloantibodies detected were anti-K (25.9%), Anti-E (21.8%), and Anti-D (9.2%), with Rhesus and K antibodies comprising 74.2% of all antibodies detected. Some risk factors were significant in several studies, including older age, female sex, older age at first transfusion, number of transfused units, and splenectomy. The prevalence of alloimmunization was significantly higher in retrospective studies compared to cross-sectional ones, in both thalassemia and sickle cell disease (P = 0.04 in each). This review reaffirmed the need to provide ABO+Rhesus + K matched blood to hemoglobinopathy patients in the Middle East, and the need for more research on Rhesus variants in this part of the world.

Red blood cell alloimmunization in blood transfusion-dependent β thalassemia major patients in Sana'a City-Yemen

The development of erythrocyte alloantibodies complicates transfusion therapy in β thalassemia major patients. These antibodies increase the need for blood and intensify transfusion complications. Data on erythrocyte alloimmunization is scarce in Yemeni thalassemia patients. We studied the frequency of alloimmunization in multitransfused β-thalassemia major patients and investigated risk factors that affect antibody formation. Blood samples were taken from 100 β thalassemia major patients who received multitransfused leukodepleted packed red-blood cells. Antibody screening and identification were performed by indirect antiglobulin test using the gel column technique. All patients were tested for autoantibodies using autocontrol and direct antiglobulin test. No adsorption test was done as no autoantibodies were detected in any patient. In our study of 100 β-thalassemia patients, 50 were male and 50 were female with ages ranging from 1 to 30 years. Alloantibodies were present in 6% of patients, while no autoantibodies were detected. Of the 17 alloantibodies identified, the majority were directed against Kell (41.2%) and Rh (29.4%) blood groups. Alloimmunization was significantly associated with age group and sex (p = 0.013, p = 0.030), respectively in β thalassemia major patients. The development of alloantibodies was not significantly associated with duration, total number of transfusions and splenectomy (P = 0.445, P = 0.125, P = 0.647). No autoantibodies found in patients with β thalassemia major. The study found low rates of erythrocyte alloimmunization in multitransfused β-thalassemia major patients, but significant alloantibodies were produced primarily from Kell and Rh blood groups, suggesting the need for providing phenotypically matched cells for selective antigens to improve transfusion efficiency.

Study of the Frequency and Specificity of Red Cell Antibodies in Patients with Hemoglobinopathies

Patients with thalassemia and sickle cell disease (SCD) require blood transfusions as part of their supportive care. However, one of the most serious side effects of this treatment is the risk of red cell alloimmunization. The goal of this study was to assess the prevalence and Specificity of red cell alloimmunization in Egyptian thalassemia and sickle cell anaemia patients. This study included 200 multi transfused Egyptian patients, one hundred and forty patients with transfusion dependent thalassaemia and sixty patients with sickle cell anaemia, who were attending the Paediatric Children Hospital-Cairo University at the period from March 2019 to October 2019. Alloantibody identification was made by Diamed- ID microtyping system. In the studied groups both thalassemia and sickle patients, the prevalence of alloimmunization was 22/200 (11%) patients. The two most often alloantibodies were, antibodies against Kell antigen (37%) and against E antigen (30%). The prevalence of alloimmunization was more in females in comparison to males, but it did not reach statistical significance and patients with thalassemia major had higher alloimmunization rates than other studied groups but was not statistically significant. In the D negative patients in the research group, alloimmunization demonstrated a statistically significant difference (p = 0.01). Age, gender, age of transfusion onset and splenectomy were not contributing factors to the antibody presence in the group of patients being investigated. Before receiving blood transfusions, extended red blood cell phenotyping should be thought of as a crucial procedure for hemoglobinopathies patients who would likely have several transfusions. It is advised that haemoglobinopathies patients in Egypt be checked through phenotyping of RBC units for Kell and all Rh antigens to be phenotyped before starting transfusion in these patients which is also standard of care for these patients presently.

Red cell alloimmunization and associated risk factors in multiply transfused thalassemia patients: A prospective cohort study conducted at a tertiary care center in Northern India

BACKGROUND

One of the complications of chronic transfusions in thalassemia is the development of red cell alloimmunization.

AIMS

The aim of the study was to determine the frequency, specificity of red cell alloantibodies, and factors influencing alloimmunization in multiply transfused thalassemia patients.

MATERIALS AND METHODS

The study was carried out prospectively on beta-thalassemia patients over 10 months. Plasma samples were used for antibody screening and identification using the column agglutination technique. Patients' clinical, laboratory, and transfusion details were obtained from hospital information system and patient files.

STATISTICAL ANALYSIS

Continuous variables were reported as median and quartile, whereas categorical variables were provided as numbers and proportions. P < 0.05 was considered statistically significant.

RESULTS

Out of 255 patients, 17 (6.6%) patients developed alloantibodies. Alloimmunized patients had significantly higher median ages at their first transfusions (1 year vs. 0.5 years; P = 0.042) than nonalloimmunized patients. Alloimmunized patients had significantly higher conjugated bilirubin (P = 0.016) and serum ferritin (P = 0.007). The majority of alloantibodies had specificity toward K antigen, followed by E, C, D, JKa, and JKb antigens. Alloimmunized patients received more units per year than nonalloimmunized patients (median, 30 vs. 24 units; P < 0.001). The average transfusion interval time between two successive transfusions showed a significant difference (P < 0.001).

CONCLUSIONS

The prevalence of alloimmunization in thalassemia patients in North India is relatively low. Since most of the alloantibodies belong to Rh and Kell blood group system, extended phenotype-matched blood for Rh and Kell will be helpful in further preventing or decreasing the development of alloantibodies in multiply transfused thalassemia patients.

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

BACKGROUND AND AIM

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

[Genotyping and its applications, a look to the future]

The detection of the most significant erythrocyte antigens present in each one of the individuals is fundamental when carrying out a transfusion or a transplant. Detection to date is performed by conventional serological methods through the antigen-antibody reaction. But several drawbacks may arise depending on the pathology under study, limiting the availability of blood components. Molecular methods such as genotyping is a tool that complements sensitivity and specificity and has come to revolutionize immunohematology in the blood bank, allowing not only the detection of erythrocyte antigens but also platelet antigens. These methodologies are applicable in patients and in large-scale donors, starting from the allelic variants present in each of the genes that code for the antigens of clinical interest, using microarray systems or systems based on particles labeled with specific probes or their variants that allow an analysis from the immunohematological point of view.

Red Blood Cell Alloimmunization Rates and Related Factors of Patients with Thalassemia in Shiraz, Iran

OBJECTIVE

The development of antibodies against red blood cell (RBC) antigens is one of the most significant adverse effects of chronic blood transfusions. This study aimed to estimate the frequency and causes of RBC immunization in patients with major thalassemia.

METHODS

The findings could help determine the limitation of current practices and help future developments in the selection of suitable blood units for the transfusion support of patients with thalassemia.

RESULTS

The alloimmunization rate was detected in 52 of 650 patients with major thalassemia (8%). The most frequent antibodies were against K (50%), D (26%), and E (15.4%). Sex, age, and splenectomy did not have any impact on the immunization rate. Immunization was lower in patients who had received only leuko-reduced blood units.

CONCLUSION

It is recommended that antibody screening before the first transfusion and extended RBC matching particularly for the most frequent antigens (ABO/Rh/Kell) should be performed for patients with thalassemia.

Expression of the immune checkpoint receptors CTLA-4, LAG-3, and TIM-3 in β-thalassemia major patients: correlation with alloantibody production and regulatory T cells (Tregs) phenotype

Alloimmunization is a serious complication in β-thalassemia major patients as a result of repeated blood transfusion. The immune checkpoint receptors play an important role in regulating immune system homeostasis and the function of the immune cells. This study aimed to evaluate the expression of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), lymphocyte activation gene 3 (LAG-3), and T-cell immunoglobulin and mucin domain-containing protein-3 (TIM-3) immune checkpoint molecules in β-thalassemia major patients with and without alloantibody. For this purpose, 68 β-thalassemia major patients with (34 patients) and without (34 patients) alloantibody as well as 20 healthy controls were enrolled. The expression of these genes was evaluated in different groups of patients by SYBR Green real-time PCR method. Our results showed that the mean expression of LAG-3 was significantly increased in thalassemia patients compared to the control group (*P < 0.001). However, there was no significant difference in expression of the CTLA-4 and TIM-3 as well as LAG-3 genes between patients with and without alloantibody (P > 0.05). A positive correlation was observed between the level of LAG-3 expression with markers associated with Treg function including FOXP3 and GDF-15 genes in β-thalassemia major patients. Taken together, the LAG-3 molecule might have a more prominent role in the abnormality of the immune system in thalassemia patients especially the function of regulatory T cells (Tregs), prior to the CTLA-4 and TIM-3 genes.

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.

A study of red blood cell alloimmunization and autoimmunization among 200 multitransfused Egyptian β thalassemia patients

The development of hemolytic erythrocyte alloantibodies and autoantibodies complicates transfusion therapy in thalassemia patients. These antibodies ultimately increase the need for blood and intensify transfusion complications. There is a scanty data on the frequency of RBC alloimmunization and autoimmunization in Egyptian β thalassemia patients as pretransfusion antibody screening is not routinely performed. We studied the frequency of alloimmunization and autoimmunization among 200 multiply transfused β thalassemia patients and investigated the factors that possibly affect antibody formation. Of the 200 patients in our study, 94 were males and 106 females, with the age range of 2–37 years. Alloantibodies were detected in 36 (18%) of the patients, while autoantibodies were detected in 33 (16.5%). The dominant alloantibodies were directed against Kell (33%) and Rh (24.4%) groups. Alloimmunization had a significant relationship with treatment duration and the frequency of transfusion (P = 0.007, 0.001, respectively). The presence of autoantibodies was significantly related to age (P = 0.001), total number of transfused units (P = 0.000) and splenectomy (P = 0.000). The high prevalence of alloimmunization in the study population disclosed the need for providing phenotypically matched cells for selective antigens especially for Kell and Rh subgroups to reduce risk of alloimmunization and increase the efficiency of blood transfusion.

Genotyping of blood groups in alloimmunized patients with β-thalassemia major by T-ARMS-PCR and multiplex-aso-pcr

INTRODUCTION

Beta-thalassemia major is a severe hemolytic anemia requiring life-long blood transfusion. Planned random donor blood transfusion is associated with alloimmunization against incompatible antigens. Determination of the minor blood group systems phenotype or genotype, and administration of the compatible blood components can significantly reduce the rate of alloimmunization. The present study aimed to determine the prevalence of alloimmunization, and genotype/phenotype characteristics of the minor blood groups systems in patients with β-thalassemia major.

MATERIAL AND METHODS

This study was conducted on 1147 β-thalassemia major patients. Initially, antibody screening and antibody identification were performed. Then, phenotyping and genotyping for the Rh, Kell, Kidd, and Duffy blood groups were done in alloimmunized patients using monoclonal antibodies and Multiplex-Allele Specific Oligonucleotide-Polymerase Chain Reaction (Multiplex-ASO-PCR) and Tetra-primer amplification refractory mutation system-PCR (T-ARMS-PCR), respectively. Any phenotype/genotype discrepancy was assessed by direct sequencing.

RESULTS

Ninety-seven (8.5 %) out of 1147 patients had alloantibodies against the minor blood group antigens (44 males, 45.4 %, and 53 female, 54.6 %). The most common alloantibodies were against the RH (n: 47, 48.5 %), and the Kell (n: 23, 23.7 %) blood groups systems. Twenty-three (2.1 %) genotype/phenotype discrepancies out of 1067 tests, including 9 in the Rh (9.3 %), 8 in Duffy (34.8 %), and 6 in Kidd (26.1 %) blood groups were detected. No discrepancy was found in the Kell blood group system. Direct sequencing revealed that the results of molecular methods were correct.

CONCLUSION

Multiplex-ASO-PCR and T-ARMS-PCR molecular methods are fast, reliable and cost-benefit molecular methods for the minor blood group genotyping in multi-transfused β-thalassemia major patients.

Red blood cell alloimmunization in Iran: A Comprehensive review of the literature

BACKGROUND:

Alloimmunization is an immune response against foreign antigens which introduced into the body through transfusion, pregnancy, or transplantation. This phenomenon is a big challenge in patients, which require regular transfusions. In the current study, we tried to have a comprehensive review on the status of alloimmunization in Iran. For this purpose, we searched for papers investigating alloimmunization in transfusion-dependent patients and also in patients with no regular transfusions who are candidate for surgery or who need blood.

METHODS:

We searched PubMed, Google Scholar, SID, and MAGIRAN databases using the following keywords: “blood transfusion,” “alloimmunization,” “alloantibodies,” “irregular antibodies,” “red cell antibodies,” and “Iran.” No limitation for the date of publication and language of the papers was defined. All the identified records were then screened for the relevance and duplication.

RESULTS:

A total of 22 papers were included in this study. All of the studies were conducted from 1999 to 2016 and providing alloimmunization data from different cities all over of Iran. In general, the results showed that the most prevalent alloantibodies are anti-Kell (anti-K antigen) and anti-Rh system, mainly anti-E, anti-D, anti-C, and anti-c.

CONCLUSION:

Anti-Kell and anti-Rh antibodies are the most prevalent antibodies responsible for alloimmunization in Iranian population.

Genotyping analysis of the MNS blood group system of thalassemia patients with alloantibodies in Iran

BACKGROUND

Serological methods are unreliable for accurate determination of blood group antigens in multi-transfused thalassemia patients. The MNS blood group system has five high-frequency antigens. Many studies demonstrated that some antibodies including anti-S, anti-s, and anti-U may cause acute and delayed transfusion reactions and hemolytic disease of the fetus and newborn. This study aimed to determine the genotype of the MNS blood group in thalassemia patients with alloantibodies by molecular methods.

MATERIAL AND METHODS

In this study, 104 blood samples from thalassemia patients were collected. The blood group phenotype for M, N, S and s antigens was determined by the tube hemagglutination method. MNS blood group genotyping was performed using PCR-SSP and DNA Sequencing methods.

RESULTS

All patients were genotyped with a total of 6 pairs of primers. Discrepancies between genotype and phenotype were observed in 22 patients with S/s alleles and 2 patients with M/N alleles, however, there was full accordance between the results of SSP-PCR and DNA sequencing. The frequency of MNS blood group alleles was determined as follows: 25 % MNSs, 23 % MNss, 21 % MMSs, 9% MMSS, 9% MMss, 8% NNss, 2%MNSS, and NNSS, NNSs, MM genotypes at 1% each.

CONCLUSION

In conclusion, molecular genotyping is more reliable than serological methods in multiple transfusion patients and can lead to a more compatible blood unit for transfusion in these patients.

Genomic analyses of KEL alleles in alloimmunized thalassemia patients from Iran

OBJECTIVES

Serological methods are unreliable for red blood cells (RBCs) antigen typing in multi-transfused thalassemia patients due to the presence of donor RBCs in the recipient's circulation and interfering antibodies. Kell blood group system is important in transfusion medicine and Kell antibodies have shown as the most prevalent antibodies in thalassemia patients. We intended to determine the genotype of Kell antigens among Iranian alloimmunized thalassemia patients using molecular methods and compare the results with serological phenotyping.

METHODS

Two hundred thalassemia patients participated in this study. Blood group phenotype was performed by the serological method, while the genotype was determined for KEL*01, KEL*02, KEL*03, and KEL*04 alleles using PCR-Sequence Specific Primer (PCR-SSP) method. The genotypes of patients with incompatibility between phenotype and genotype were re-evaluated by Restriction Fragment Length Polymorphism-PCR (RFLP-PCR) and confirmed by DNA sequencing in all cases.

RESULTS

Ten patients were found with discrepancies between genotype and phenotype; however, there was a complete agreement between the results of SSP-PCR, RFLP-PCR, and DNA sequencing. Six discrepancies were found in the KEL*01/KEL*02 allele when serologically phenotyped as K-k+. One patient with K-k- and three patients with Kpa-Kpb + phenotype were identified as KEL*01/KEL*02 and KEL*03/KEL*04, respectively.

CONCLUSION

It can be concluded that molecular genotyping is more reliable compared with the serological method, especially in the patients who have received multiple transfusions. Therefore, using a combination of these techniques can lead to a better matched transfusion in these patients.

Alloimmunization and autoimmunization in adult transfusion-dependent thalassemia patients: a report from a comprehensive center in Israel

Patients with beta thalassemia major (TM) are transfusion-dependent (TD) since early childhood and for life. Development of alloantibodies and autoantibodies against red blood cell (RBC) antigens is increasingly recognized as a significant transfusion hazard, especially among heavily transfused patients. The aim of this study is to assess RBC alloimmunization and autoimmunization rates in TD TM patients treated in our Comprehensive Center of Adult Thalassemia, Hemoglobinopathies and Rare Anemias. TD TM patients, regularly transfused every 2-3 weeks, were included in the study. Clinical and RBC transfusion records, including RBC antibodies, since diagnosis in early childhood, were retrieved from patients' files and from the blood bank database. Forty TD TM patients, > 18 years of age, were included in the study. Alloimmunization was demonstrated in 17 (42.5%) patients. Thirty-four alloantibodies were detected, with the most frequent being RH related (12 of 34, 35.3%) followed by those of the Kell system (8 of 34, 23.5%). Age at first transfusion was positively related to the probability of developing alloantibodies (p = 0.02). Splenectomy was found to be correlated with developing alloantibodies (p = 0.016). Logistic regression analysis of the lifelong probability of developing alloantibodies on the age at first transfusion and splenectomy demonstrates a strong positive relationship (p = 0.002). A substantially high rate of alloimmunization was found among adult TD TM patients. Early initiation of RBC transfusions, avoidance of splenectomy and extended Rh and K antigen matching, can reduce the incidence of alloimmunization in TD TM patients.

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.

Red cell alloantibodies in beta-thalassaemia major patients' blood referring to the regional blood transfusion center of Tehran, Iran

Introduction: Thalassemia is associated with a genetic decline in the rate of synthesis of one or more types of natural hemoglobin polypeptide chains. One of the major complications in thalassemia patients is alloimmunization, which is antibody production by the patient against transfused red blood cells (RBCs). These RBCs are unknown by the recipient and the formed antibodies against them are called alloantibodies. This study aimed to evaluate the frequency of alloantibodies against RBCs in beta-thalassemia patients referred to Tehran Regional Blood Transfusion Center.

Methods: In this study, antibody screening tests (Dia-cell I, II, and III) were performed on 184 thalassemia patients. An identification test by the Dia panel consisting of 11 different O RBCs groups to examine sera with Dia cells (I, II, or III) was performed.

Results: In our study, males and females patients comprised 66 (35.87%) and 118 (64.13%), respectively, of whom 116 (63%) had alloimmunization. In addition, 68 thalassemia subjects (37%) lacked alloantibodies. Among 184 patients with beta-thalassemia major, anti-K (Kell system), anti-D, and anti-E (Rhesus system) had the most abundant alloantibody variants with an incidence of 24 (13%), 11 (5.98%), and 10 (5.4%), respectively.

Conclusion: Before RBC transfusion, regular RBC antigen phenotypes, as well as problem-solving of alloantibody production by receiving compatible blood for Kell and RH subgroups, are suggested for all cases of transfusion-derived thalassemia.

Evaluation of regulatory T cells frequency and FoxP3/GDF-15 gene expression in β-thalassemia major patients with and without alloantibody; correlation with serum ferritin and folate levels

β-thalassemia major is one of the most common hematologic disorders in the world. It causes severe anemia and patients require regular blood transfusions, which causes different complications such as iron overload and alloimmunization. Regulatory T cells (Tregs) have an important role in regulation of immune responses. FoxP3 is the major marker of Tregs and its expression can be influenced by different factors. GDF-15 is another gene that plays a role in iron homeostasis and regulation of immune system in different diseases. The aim of this study was to assess the frequency of Tregs and FoxP3/GDF-15 gene expression in β-thalassemia major patients with and without alloantibody as well as its correlation with different factors such as serum ferritin and folate levels. This study was conducted on 68 β-thalassemia major patients with and without alloantibodies in comparison with 20 healthy individuals with matched age and sex as control group. Enzyme-linked immunosorbent assay (ELISA), flow cytometry, and real-time PCR were performed in order to evaluate serum ferritin and folate levels, frequency of Tregs, and the expression of FoxP3 and GDF-15 genes, respectively. The percentage and absolute count of Tregs were increased in patients compared with controls (P = 0.0003), but there was no difference between responders and non-responders (P > 0.05). The Tregs count correlated positively with serum ferritin. No correlation was observed between target genes and serum ferritin and folate, but there was a positive significant correlation between the expression of FoxP3 and GDF-15 genes, which shows the immunosuppressive role of GDF-15.

Study of Frequency and Characteristics of Red Blood Cell Alloimmunization in Thalassemic Patients: Multicenter Study from Palestine

Background. β-Thalassemia is a common inherited hemolytic disorder in Palestine. Red blood cell (RBC) transfusion is the principal treatment but it may cause RBC alloimmunization. This study was conducted to determine the prevalence and characteristics of RBC alloimmunization among thalassemic patients in northern governorates of Palestine. Methods. A prospective multicenter observational study was conducted in the thalassemia transfusion centers in the northern governorates of Palestine. The study included 215 thalassemia patients who received regular blood transfusions. Clinical and transfusion records of patients were examined. Antibody screening and identification was conducted using the microcolum gel technique. Results. Two hundred fifteen patients were included in the study. More than half (52.1%) of the patients were males. The median age of patients was 18 years (range: 12–24 years). The most frequent blood group was A (40.5%). Alloantibodies were detected in 12.6% of patients. Anti-D (33.3%), anti-K (25.9%) and anti-E (14.8%) were the most commonly isolated antibodies. There was no association between age, sex, starting age of transfusion, number of transfused units, history of splenectomy and alloimmunization. Conclusions. Anti-Rh and anti-K antibodies were common among this cohort of patients. Age, sex, starting age of transfusion, number of transfused units, and history of splenectomy could not predict the occurrence of alloimmunization.

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.

Red blood cell alloimmunisation in transfusion-dependent thalassaemia: a systematic review

BACKGROUND

Chronic red blood cell transfusion is the first-line treatment for severe forms of thalassaemia. This therapy is, however, hampered by a number of adverse effects, including red blood cell alloimmunisation. The aim of this systematic review was to collect the current literature data on erythrocyte alloimmunisation.

MATERIALS AND METHODS

We performed a systematic search of the literature which identified 41 cohort studies involving 9,256 patients.

RESULTS

The prevalence of erythrocyte alloimmunisation was 11.4% (95% CI: 9.3-13.9%) with a higher rate of alloimmunisation against antigens of the Rh (52.4%) and Kell (25.6%) systems. Overall, alloantibodies against antigens belonging to the Rh and Kell systems accounted for 78% of the cases. A higher prevalence of red blood cell alloimmunisation was found in patients with thalassaemia intermedia compared to that among patients with thalassaemia major (15.5 vs 12.8%).

DISCUSSION

Matching transfusion-dependent thalassaemia patients and red blood cell units for Rh and Kell antigens should be able to reduce the risk of red blood cell alloimmunisation by about 80%.

Study of red blood cell alloimmunization risk factors in multiply transfused thalassemia patients: role in improving thalassemia transfusion practice in Fayoum, Egypt

BACKGROUND

β-Thalassemia is considered the most common chronic hemolytic anemia in Egypt. Alloimmunization can lead to serious clinical complications in transfusion-dependent patients. The objective of this study was to determine the frequency and types of alloantibodies, and, in addition, to study the risk factors that might influence alloimmunization in multiply transfused thalassemia patients in Fayoum, Egypt, with the goal that this study could help minimize some of the transfusion-associated risks in those patients.

STUDY DESIGN AND METHODS

A total of 188 multiply transfused thalassemia patients attending Fayoum University Hospital were analyzed. Alloantibody identification was performed by DiaMed-ID microtyping system.

RESULTS

Alloimmunization prevalence was 7.98%. The most common alloantibody was D-related; anti-D was the most frequent alloantibody found in eight of the 188 patients (4.25 %), followed by anti-C in two patients (1.1%), anti- E in two (1.1 %), anti-c in two (1.1 %), anti-Fya in two (1.1%), anti-K in one (0.53 %), and an unknown antibody in one patient (0.53%). Higher rates of alloimmunization were found in female patients, in patients with β-thalassemia intermedia, in splenectomized patients, in D- patients, and in patients who started blood transfusion after 3 years of age.

CONCLUSION

The study reemphasizes the need for cost-effective strategy for thalassemia transfusion practice in developing countries. Red blood cell antigen typing before transfusion and issue of antigen-matched or antigen-negative blood can be made available to alloimmunized multiply transfused patients. Early institution of transfusion therapy after diagnosis is another means of decreasing alloimmunization.

Red blood cell alloimmunization in multitransfused patients in a tertiary care center in Western India

OBJECTIVE

To investigate the seroprevalence and specificity of red blood cell (RBC) antibodies in multitransfused patients, in whom the risk of alloimmunization is especially high.

METHODS

We conducted a retrospective study on blood specimens from 200 multitransfused patients. We evaluated all specimens for alloimmunization using various immunohematological tests via the column agglutination technique.

RESULTS

The overall prevalence of RBC alloantibodies was 5.5%. Of the 11 specific types of alloantibodies identified, most (72.7%) belonged to the Rh blood group system, followed by the S, M, and Lewis blood group systems (9.1% each).

CONCLUSION

Most alloantibodies were of the Rh blood group specificity. To improve the quality of blood supplied, especially to patients with thalassemia, we recommend that Rh phenotyped, cross-match-compatible blood should be issued to prevent complications such as acute and delayed hemolytic reactions.

Study of alloimmunization and autoimmunization in Iranian β-thalassemia major patients

Background:

Thalassemia is one of the most common monogenic disorders characterized by reduced production of globin chains. Although regular red blood cell (RBC) transfusion support is the main treatment for these patients, it may be associated with complications such as RBC alloimmunization.

Aim:

The study aimed to determine the incidence of alloimmunization and autoimmunization to RBC antigens in β-thalassemia major patients from Zanjan, Zanjan Province, Iran.

Materials and Methods:

A total of 49 β-thalassemia major patients comprising 24 females and 25 males (mean age: 18.59 ± 8.16 years; range: 2-40 years) from Northwest Iran were included in a cross-sectional study. Alloantibody screening and identification were done using 3-cell and 10-cell reagent red blood cells, respectively. Autoantibody detection was performed using direct Coomb's test.

Results:

The incidence of alloimmunization was 16.32% with 10 alloantibodies identified in 8 patients. The most common clinically significant alloantibody identified in alloimmunized patients was anti-Kell (K-antigen) (60%) followed by anti-Rhesus (Rh) (E, c-antigens). The rate of alloimmunization was significantly lower in patients transfused with leukoreduced RBCs compared with those transfused with nonleukoreduced RBCs (9.53% vs 57.14%, P = 0.001). There was no significant correlation between alloantibody formation and the age, gender, hemoglobin levels, number of transfused units, and splenectomy.

Conclusion:

Transfusion of leukoreduced and phenotypically matched red blood cells for Kell (K) and Rh (E, c) antigens may help reduce the alloimmunization rate in Iranian β-thalassemia major patients. Moreover, autoimmunization to RBC antigens was rare in our patients.

Predictors of Red Cell Alloimmunization in Kurdish Multi Transfused Patients with Hemoglobinopathies in Iraq

Hemoglobinopathies are significant health problems in Iraq, including its Northern Kurdistan region. One of the essential components of management of these disorders is regular lifelong blood transfusions. The latter is associated with several complications including red cell alloimmunization. No study has looked at the frequency of alloimmunization and its associations in the country. To address the latter issue, 401 multi transfused patients [311 with β-thalassemia (β-thal) syndrome and 90 with sickle cell disease], registered at a large thalassemia care center in Iraqi Kurdistan had their records reviewed, and their sera tested for atypical antibodies using screening and extended red cell panels. Red cell alloimmunization was detected in 18 patients (4.5%) with a total of 20 alloantibodies, while no autoantibodies were detected. The most frequent alloantibody was anti-E, followed by anti-D, anti-K, anti-C(w), anti-C, anti-c and anti-Le(a). Ethnicity was an important predictor of alloimmunization, while age at start of transfusion (>2 vs. ≤2 years) (p = 0.005), Rhesus D (RhD) negative status (p = 0.0017) and history of previous transfusion reactions (p = 0.007) showed a statistically significant higher rate of alloimmunization. However, patients' age, gender, number of units transfused, underlying diagnosis and splenectomy were not significantly associated with alloimmunization. Based on our observations, measures to reduce alloimmunization rates may include extended matching for Rhesus and Kell antigens and early initiation of blood transfusions.

Red cell alloimmunisation in regularly transfused beta thalassemia patients in Pakistan

BACKGROUND

In Pakistan routine blood group typing of thalassemia patients identifies ABO and Rh(D) antigens only. Therefore, other antigen incompatibilities between blood donor and blood recipient may cause alloimmunisation.

OBJECTIVE

The aim of this study was to estimate the frequency of alloimmunisation and to evaluate the risk factors associated with its development in beta (β)-thalassemia patients receiving regular blood transfusions.

MATERIALS AND METHODS

In total 162 β thalassemia patients were included in this study. An extended red cell antigen panel was performed to detect antibodies. Patients received red cell concentrates, which were matched for ABO and Rh(D) antigens. Clinical and laboratory data were collected and analysed to estimate the frequency of alloantibodies and the factors influencing immunisation in patients on regular blood transfusion.

RESULTS

The median age of patients was 6·7 (range: 0·5-25) years. A total of 14 (8·6%) patients developed alloantibodies against red cell antigens. The most frequently occurring alloantibodies was anti-E (2·5%), anti-K (1·8%), anti-e (1·2%) and anti-D (0·6%). Five (3·1%) patients developed more than one red blood cell (RBC) alloantibody. Age at first transfusion in alloimmunised patients was 1·22 ± 0·87 years. The frequency of blood transfusion in alloimmunised patients was 23 ± 8·81 days and in those without alloimmunisation was 31·8 ± 16 days (p = 0·02). Logistic regression analysis showed no independent risk factor associated with alloimmunisation.

CONCLUSION

The frequency of transfusion was increased in patients who developed alloantibodies. Typing patients and donors to match for Rh and Kell antigens would prevent more than 90% of RBC alloantibodies and reduce the frequency of transfusion in thalassemia patients.

Prevalence of Alloimmunization to Human Platelet Antigen Glycoproteins and Human Leucocyte Antigen Class I in β Thalassemia Major Patients in Western India

Present management of β thalassemia major by regular packed red blood cell (PRBC) transfusions poses risk of alloimmunization not only to red blood cell antigens, but also to human platelet antigens (HPA) and Human leucocyte antigens class I (HLA I). However data in this context is very limited in Indian population. The aim of the study was to determine the prevalence of alloimmunization to HPA and HLA I in β thalassemia major patients who have received multiple PRBC transfusions over the years. A cross sectional study was performed at our tertiary care blood bank. β thalassemia major patients of more than 6 years of age were included who were receiving fresh, leucoreduced and irradiated PRBC units regularly with annual requirement of more than ten PRBC transfusions. A total of 9 out of 80 (11.25 %) patients were found to be alloimmunized for HPA antigens of various specificity and 24 out of 80 (30 %) developed antibodies to HLA I. The awareness of development of alloimmunization to HPA and HLA antigens in multi PRBC transfused thalassemics, despite use of leucofilters will prompt us, to look for improvement in our current PRBC preparations to minimise platelet alloimmunisation. Further studies are required to validate the findings and build the base line data in this regard. This is of importance, especially in view of providing suitable cross-matched platelets when required in future especially when considering future haematopoietic stem cell transplantation (HSCT).

Red blood cell antibodies in thalassemia patients in northern India: risk factors and literature review

Study of the factors responsible for red cell alloimmunization can help in adopting appropriate strategy to minimize alloimmunization. However data for thalassemia patients from our region is limited. Therefore, a study was conducted to find out the frequency and the factors associated with red cell allo and autoimmunization in thalassemia patients at our center so as to enable us to take appropriate action to reduce alloimmunization. Clinical, demographic, allo and autoantibody and transfusion records of 280 thalassemia patients at our hospital were studied. Patients with and without alloantibodies were compared to find significant differences for age, gender, race, age at start of regular transfusions and splenectomy. Red cell antigen frequencies in thalassemia patients and published antigen frequencies in blood donors from the same center were compared to look antigen differences as a risk factor for alloimmunization. Twenty four thalassemia patients (8.6 %) developed 28 clinically significant alloantibodies. 18 (65 %) of the alloantibodies were of Rh system. The three most common antibodies detected was anti E (11, 39.3 %) followed by anti K (6, 21.4 %) and anti c (10.8 %). Five (1.8 %) of the 280 patients developed autoantibodies. Patient age was found to be significantly higher in alloimmunized patients than in non alloimmunized patients. Red cell antigen frequencies between blood donor and recipient populations were found to be homogenous for most of the relevant RBC antigens. The frequency of red cell alloimmunization in thalassemia patients from our center is moderate. In this setting of red cell phenotype concordant donor-recipient population requirement of extended phenotype matched transfusions may not be cost effective.

Guidelines for diagnosis and management of Beta-thalassemia intermedia

Beta-thalassemia intermedia (β-TI) is a genetic variant of beta-thalassemias with a clinical disorder whose severity falls between thalassemia minor and thalassemia major. Different genetic defects are involved in this disorder and, based on severity of disease, clinical complications like skeletal deformities and growth retardation, splenomegaly, extramedullary hematopoiesis, heart failure, and endocrine disorders may be present in untreated patients. Precise diagnosis and management are essential in these patients for prevention of later clinical complications. Diagnosis of TI is based on clinical and laboratory data. There are some treatment strategies like modulation of gamma-globulin chain production with hydroxyurea or other drugs, transfusion, splenectomy, and stem cell transplantation. Iron chelation therapy is also needed in many of these patients even if they are not transfused. The aim of this manuscript is to review the clinical manifestations, complications, genetic defects, and unmet treatments needs in TI.

Alloimmunization and autoimmunization in transfusion dependent thalassemia major patients: Study on 319 patients

BACKGROUND

The development of anti-red blood cell antibodies (both allo-and autoantibodies) remains a major problem in thalassemia major patients. We studied the frequency of red blood cell (RBC) alloimmunization and autoimmunization among thalassemia patients who received regular transfusions at our center and analyzed the factors, which may be responsible for development of these antibodies.

MATERIALS AND METHODS

The study was carried out on 319 multiply transfused patients with β-thalassemia major registered with thalassemia clinic at our institute. Clinical and transfusion records of all the patients were examined for age of patients, age at initiation of transfusion therapy, total number of blood units transfused, transfusion interval, status of splenectomy or other interventions. Alloantibody screening and identification was done using three cell and 11 cell panel (Diapanel, Bio-rad, Switzerland) respectively. To detect autoantibodies, autocontrol was carried out using polyspecific coombs (IgG + C3d) gel cards.

RESULTS

Eighteen patients out of total 319 patients (5.64%) developed alloantibodies and 90 (28.2%) developed autoantibodies. Nine out of 18 patients with alloantibodies also had autoantibodies. Age at first transfusion was significantly higher in alloimmunized than non-immunized patients (P = 0.042). Out of 23 alloantibodies, 52.17% belonged to Rh blood group system (Anti-E = 17%, Anti D = 13%, Anti-C = 13%, Anti-C(w) = 9%), 35% belonged to Kell blood group system, 9% of Kidd and 4% of Xg blood group system.

CONCLUSION

Alloimmunization was detected in 5.64% of multitransfused thalassemia patients. Rh and Kell blood group system antibodies accounted for more than 80% of alloantibodies. This study re-emphasizes the need for RBC antigen typing before first transfusion and issue of antigen matched blood (at least for Rh and Kell antigen). Early institution of transfusion therapy after diagnosis is another means of decreasing alloimmunization.

RBC alloimmunization and double alloantibodies in thalassemic patients

PURPOSE

Alloimmunization is a common consequence of chronic blood transfusion. Double alloantibody production may complicate the condition of such patients especially for finding matched blood. In this study, we evaluated the frequency of alloantibodies in thalassemic patients with previous history of transfusion reactions.

SAMPLES AND METHODS

This study was performed on 441 multiply transfused thalassemia patients Antibody screening test was carried out using three cell-panel by gel method. Positive patients were followed up for antibody identification using 11-cell panel. Direct combs' test was performed to detect auto antibodies.

RESULTS

In a total of 441 cases (362 thalassemia major and 79 intermedia), 234 were males (53.1%) and 207 females (46.9%); mean age 22 years, range 3-61 years. Alloimmunization was detected in 50(11.3%) patients, including 37(74%) patients with one alloantibody, 8(16%) with two antibodies, 4(8%) patients with unknown antibodies and one patient (2%) with autoantibody. The most common alloantibodies were anti-Rh antibodies (-E/e/C/c/Cw) (26%), anti-K (28%), anti-D (16%), and anti-Colton (4%). Double antibodies were detected in eight out of 50 patients, including: Anti-D+anti-C (8%), anti-D+anti-E (2%), anti-Kell+anti-D (2%), and anti-Kell+KPa (2%). A significant association was observed between the transfusion reaction history and the alloantibody detection results (p < 0.05).

CONCLUSION

Antibody production against RBC antigens makes hard condition in regular blood transfusion. Double antibodies production may more complicate this situation. Thus, it is advisable to phenotype patients and matches the red cells in multiply transfused thalassemia patients.

Predictors of Red Cell Alloimmunization in Multitransfused Egyptian Patients With β-Thalassemia

Context.—Thalassemia is a major health problem in Egypt. Red blood cell alloimmunization is an important complication in transfusion-dependent patients.

Objectives.—To determine alloimmunization prevalence in Egyptian patients with β-thalassemia and to evaluate risk factors that could influence alloimmunization, with the hope of minimizing transfusion-associated risks in those patients.

Design.—Records of 272 patients with β-thalassemia who are receiving regular blood transfusions, matched for ABO-Rh(D), were analyzed. Alloantibody identification was performed by DiaMed-ID microtyping system. Autoantibodies were detected by direct Coombs test.

Results.—Alloimmunization incidence was 22.8% with 123 alloantibodies detected in 62 patients. The most common alloantibody was Rh-related (37.4%; 46 of 123), comprising anti-E (14.6%; 18 of 123), anti-D (8.9%; 11 of 123), anti-C (8.9%; 11 of 123), and anti-c (4.9%; 6 of 123), followed by anti-Kell (26%; 32 of 123), → anti-MNS (9.8%; 12 of 123), → anti-Kidd (8.9%; 11 of 123) → anti-Duffy (8.1%; 10 of 123), → anti-Le (5.7%; 7 of 123), → anti-Lu (2.4%; 3 of 123), and → anti-P1 (1.6%; 2 of 123). Anti-D antibodies developed in 34.5% of all Rh-negative patients. Eighty percent of all anti-D antibodies developed in patients older than 18 years. Males had the highest alloimmunization incidence. Alloimmunization incidence increased with the number of units transfused (P = .01). Patients who received unfiltered blood had a higher alloimmunization rate than did those who always received leukoreduced blood (P &lt; .001). Splenectomized patients had a higher alloimmunization rate (32%; 40 of 125) than did those who did not have a splenectomy (16.3%; 24 of 147; P = .003). Autoantibodies occurred in 1.5% (4 of 272) of all patients.

Conclusion.—Transfusion of leukoreduced and phenotypically matched cells for selective antigens may help reduce expenses and risks of alloimmunization in patients with thalassemia.

Detection and identification of red cell alloantibodies in multiply transfused thalassemia major patients: a prospective study

Life long red blood transfusion remains the main treatment for β thalassemia major patients. The development of alloantibodies complicates transfusion therapy in thalassemia patients. Alloimmunization to red cell antigens is one of the most important immunological transfusion reaction and causes delayed type of transfusion reaction. A prospective study was conducted from January 2007 to January 2010. This was a cohorts of 115 patients were selected from regular transfusion group and they were followed for two and half year. They were followed up for the effect of transfusion during study period. There was a decline in patient number from 115 to 96 due to mortality and transfer of patient. A total of 96 multiply transfused thalassemia patients were prospectively included in this study and three consecutive samples collected after every 6 months and investigated for the development of alloantibody to red cell antigens. Tests for antibody screening and identification were performed on preserved sample to investigate prevalence and development of red cell alloimmunization by standardized laboratory techniques by same person at Prathama Blood Centre. A total of 96 patients were included in the study. 63 patients were males and 33 females. A total of five single alloantibodies were formed in five patients out of them four (80 %) belonged to Kell blood group system and one (20 %) from Rh system. It was observed that two (1.92 %) of new thalassemia patients developed red cell alloantibodies during study period. Red cell alloimmunization should be kept in mind in the patients receiving multiple transfusions. In present study, alloimmunization rate was 5.21 %. Mean transfusion duration in these patients was 23.90 days, probably due to presence of alloantibody. RBC alloantibody detection on regular interval and corresponding antigen negative blood transfusion is strongly recommended in transfusion dependent thalassemia patients.

Autoimmune hemolytic anemia in patients with β-thalassemia major

Hemolysis is a common feature in patients with β-thalassemia major. As a result, autoimmune hemolytic anemia complicating β-thalassemia is easily overlooked. Here, the authors described the clinical features and management of 7 patients with β-thalassemia major and autoimmune hemolytic anemia. These patients had fever, cough, and tea-colored urine on admission. The laboratory investigations showed a significant drop in hemoglobin and increased serum bilirubin. Coombs' tests revealed that anti-immunoglobulin G (IgG) and anti-C3 was positive in 7 and 5 cases, respectively, whereas anti-Rh E alloantibody was positive in 3 cases. All the patients received corticosteroids treatments and blood transfusions. Patients with anti-Rh E alloantibodies also received immunoglobulin treatments. Six of the patients responded well to the management, but 1 patient developed recurrent autoimmune hemolytic anemia that required cyclosporin A treatment. All the patients remained well by following up for more than 6 months.

High frequency of autoimmunization among transfusion-dependent Tunisian thalassaemia patients

BACKGROUND

Limited data are available on the frequency of RBC alloimmunization and autoimmunization in transfusion-dependent Tunisian β thalassaemia patients.

MATERIALS AND METHODS

We analyzed the clinical and transfusion records of 130 patients (57 females and 73 males; mean age 119 months; range 12-11 months) with β thalassaemia major and who had regular blood transfusions for periods ranging from 12 to 311 months.

RESULTS

Of the 130 patients, ten (7.7%) developed RBC alloantibodies. The most common alloantibodies were directed against antigens in the Rh systems. Erythrocyte-autoantibodies as determined by a positive direct antiglobulin Coombs test, developed in 52(40%) patients with and without underlying RBC alloantibodies, thereby causing autoimmune haemolytic anaemia in eleven patients (21%).

CONCLUSIONS

Autoimmunization to erythrocyte antigens is a frequent complication in patients with β thalassaemia major. Several factors might have contributed to the high autoimmunization rate observed in this study, including non phenotypic blood exposure and alloantibody formation prior to positive Coombs test.

Blood transfusion and alloimmunization in patients with thalassemia: multicenter study

One of transfusion's side effects is alloimmunization against red blood cell (RBC) antigens. Early diagnosis by antibody screening is an important step in the detection of these alloantibodies. The authors studied the frequency of alloimmunization in thalassemic patients of 4 centers (2 adult and 2 pediatric centers) and compared the rates in children (up to 15 years) and adults. Antibody screening tests were performed by gel method according to its standard pattern and respective program. In positive cases, antibody identification test by gel method was performed. Eight hundred thirty-five patients were studied; 548 (65.6%) were adults (mean age = 24.5), and 287 (34.4%) cases were pediatrics (mean age = 10.05). Of these patients, 74.1% had no history of transfusion reaction, whereas 21 (2.5%) had hemolytic complications. Seventy-eight (9.3%) exhibited allergic symptoms, and 117 (14%) cases experienced febrile reactions during transfusion. Antibody screening showed positive results in 22 pediatric cases (7.7%) and 79 adults (14.4%); 72 (71.3%), 19 (18.8%), 3 (3%), and 1 (1%) cases exhibited single, double, triple, and autoantibodies, respectively. Anti-Kell antibody was seen in 34 (33.7%) cases, anti-D was seen in 11 (10.9%) cases, and anti-E in was seen in 10 (9.9%) cases. The authors observed 8 anti-D+C (7.9%) cases, 1 anti-D+E (1%), 3 anti-Kell+E, 3 anti-Kell+Kpa (3%), and 1 anti-Kell+D double antibodies. These antibodies were also a combination of Rh subgroups or Rh and Kell subgroups. The authors observed meaningful relations between history of transfusion reactions and age with antibody screening results (P = .005). Based on alloantibodies types, more than two thirds of them were Rh subgroups and Kell groups. Phenotype determination of RBCs before beginning chronic blood transfusion and careful cross-matching with Kell and Rh subgroups in addition to ABO may help reduce alloimmunization in chronic transfusion patients.

Alloimmunization and erythrocyte autoimmunization in transfusion-dependent Egyptian thalassemic patients

BACKGROUND

Alloimmunization to red blood cells' (RBCs) antigens and formation of autoantibodies against RBCs is a frequent complication among immunocompetent transfusion-dependent patients. Autoantibodies can result in clinical hemolysis and difficulty in cross-matching blood. The objective of this study was to evaluate the presence of alloantibodies and autoantibodies in regularly transfused β-thalassemic patients and the factors influencing the development of alloantibodies.

MATERIALS AND METHODS

The clinical and transfusion records of 95 Egyptian β-thalassemic patients, with a mean age of 17.07 years, presenting to the National Blood Transfusion Centre for regular blood transfusion were evaluated for alloimmunization and antibody formation.

RESULTS

Alloantibodies were encountered in 27 patients (28.4%). The most frequent alloantibodies encountered were anti-Kell (23.6%) and anti-E (23.6%). Patients with blood group O were the highest in developing antibodies (37.9%). Patients with blood phenotypes R2r Kell negative developed more alloantibodies. Autoantibodies were encountered in only 1 patient.

CONCLUSIONS

Alloimmunization to RBCs' antigens is a frequent finding among Egyptian transfusion-dependent thalassemic patients, with the majority of patients being transfused with blood matched for ABO and D antigens only. Absence of phenotypically matched donors, except for a limited number of patients, may have contributed to this problem.

Red Cell Alloantibodies in Multiple Transfused Thalassaemia Patients

BACKGROUND

Thalassaemia major patients require lifelong transfusion support due to which they are prone for alloimmunization to foreign RBCs. Alloimmunization can be prevented by extended phenotype match blood transfusion. The study was conducted to know the extent of problem of alloimmunization and to find important red cell antibodies in thalassaemia patients.

METHODS

A cross-sectional study was conducted. A total of 32 thalassaemia patients were enrolled. The specimen was subjected to red cell alloantibody and autoantibody by column gel agglutination technique. R 1 (w) R 1 , R 2 R 2 , rr (papaine and non papain) and 11 cell panel reagent cells were used in screening and identification of alloantibodies respectively.

RESULT

Six (18.8 %) subjects were alloimmunized. All alloimmunized subjects were recipient of more than 20 units of transfusion. Total seven clinically significant alloantibodies were identified. Anti E and anti c were commonest antibodies in four (12.5%) patients.

CONCLUSION

Red cell alloimmunization is an important risk in thalassaemia patient. 71.4% of alloantibodies were anti E and anti c type. Extended phenotype match blood transfusion for Rh-c and Rh-E antigens or level 2 antigen matching stringency needs to be explored in preventing alloimmunization in thalassaemia patients.

Alloimmunization and red cell autoimmunization in multitransfused thalassemics of Indian origin

Transfusion therapy in thalassemia is a double edged sword, on the one hand, it is a major life saving modality, while on the other hand, it can lead to complications such as alloimmunization. The rates of alloimmunization have been variably reported across the world; however, there is a paucity of such literature among Indian thalassemics. We studied the frequency of alloimmunization and autoimmunization among 211 multitransfused thalassemics of Indian origin. All the patients have been receiving blood matched for ABO and Rh(D) antigens only. Direct antiglobulin test was performed on all patients to detect autoantibody while antibody screening (using 3-cell panel) and antibody identification (11-cell panel) were carried out to detect the presence of alloantibody. The frequency of alloimmunization was 3.79% and that of autoimmunization was 0.47%. The alloantibodies identified were anti-E, anti-K, anti-D, anti-Kp(a), anti-C(w), anti-c and anti-Jk(a). In the present study, no significant association was observed between splenectomy and the development of alloantibodies as well as between age at initiation of transfusion and alloimmunization. To conclude, there is a need to formulate a balanced and cost-effective approach for transfusion management of thalassemics to minimize alloimmunization and autoimmunization.

Red cell alloimmunization and autoantibodies in Egyptian transfusion-dependent thalassaemia patients

INTRODUCTION

The objective of this study was to explore the frequency of red cell alloantibodies and autoantibodies among β-thalassaemia patients who received regular transfusions.

MATERIAL AND METHODS

This study included 501 patients with β-thalassaemia. This work planned to study the presence of alloantibodies and autoantibodies to different red cell antigens in multitransfused thalassaemia patients using the ID. Card micro typing system.

RESULTS

Of a total of 501 β-thalassaemia patients included in the study, 11.3% of patients developed alloantibodies; 9.7% of these alloantibodies were clinically significant. The most common alloantibodies were anti-K, anti-E and anti-C. The rate of incidence of these alloantibodies was 3.9%, 3.3% and 1.7% respectively. Autoantibodies occurred in 28.8% of the patients and 22.1% of these antibodies were typed IgG. There was a significant association between splenectomy with alloimmunization and autoantibody formation (p = 0.03, p = 0.001 respectively). There was no significant association between alloantibody, autoantibody formation and number of transfused packed red cells.

CONCLUSIONS

Alloimmunization to minor erythrocyte antigens and erythrocyte autoantibodies of variable clinical significance are frequent findings in transfused β-thalassaemia patients. There is an association between absence of the spleen and the presence of alloimmunization and autoantibody formation.

Red cell alloimmunization in multitransfused patients and multiparous women

PURPOSE

To determine the incidence of alloimmunization against red cell antigens and the thermal amplitude and specificity of antibodies in multitransfused patients and multiparous women.

METHODS

Antibody screening was performed in 30 nontransfused orthopedic surgery cases (control), 504 multitransfused patients and 325 multiparous women. Antibody screening at 4°C, 22°C and 37°C was carried out in a saline phase, by indirect antiglobulin technique (IAT), using papain cystein, low ionic strength solution (LISS) and polyethylene glycol (PEG).

RESULTS

In multitransfused patients IgM antibodies were more frequently detected at 4°C and the IgG antibody incidence was 7.1% by enzyme method, 7.7% IAT, 9.4% LISS, 10.2% using PEG & 10.2% multiparous women. Bad obstetric history cases had significantly higher incidence of alloimmunization. The antibody specificity of antibodies was mainly in Lewis, Rh, Kidd and MN systems.

CONCLUSION

Antibody screening before transfusion, at set time intervals after transfusion and during antenatal period is recommended.