Transfusion medicine in a developing country - alloantibodies to red blood cells in multi-transfused patients in Saudi Arabia

Prevalence of Red Blood Cell Alloimmunization Among Pediatric Patients With Sickle Cell Disease in Saudi Arabia

OBJECTIVE

Sickle cell disease (SCD) is a common hereditary hemoglobin disorder worldwide. One of the main treatments for patients with SCD is the requirement for blood transfusions. Posttransfusion alloimmunization with red blood cell (RBC) antigens continues to be a major risk factor for SCD. The objective of this study was to determine the rate, nature, and risk factors of red cell alloimmunization among pediatric patients with SCD in our center and compare our results with published reports from Saudia Arabia SA, regional countries, and some international countries.

MATERIALS AND METHODS

A retrospective chart review of patients with SCD at King Abdulaziz Medical City-Jeddah, between 2008 and 2019 was performed. Demographic characteristics and transfusion histories were recorded. Blood samples were analyzed for alloimmunization using immunohematologic techniques.

RESULTS

In total, 121 patients were analyzed. Alloantibodies were detected in 21 patients (17.4%) and were mostly single in 15 patients (71.4%), anti-K (23.7%), anti-E (19.0%), and anti-S (9.5%). The other 6 patients (28.6%) had multiple alloantibodies, especially the combination of anti-C and anti-K (9.5%) and the combination of anti-C and anti-E (9.5%). Alloantibody levels were significantly higher in patients with frequent hospital admissions (>5 times annually), those who had an exchange blood transfusion, those younger than 3 years old, and those who received a larger number of blood units ( P ≤0.05).

CONCLUSION

The rate of RBC alloimmunization is determined and considered relatively low compared with that in other nations. Matching for extended RBC antigens to include ABO, RH (D, C, c, E, e), K, Fy a , Fy b , Jk a , and Jk b antigens in the screening panel for donors and recipients is highly recommended to ensure better transfusion practices and avoid transfusion-related complications.

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

Background

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

Methods

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

Results

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

Conclusion

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

Red Blood Cell Alloimmunization in Pediatric group with Beta Thalassemia: A Five-Year Experience

Beta-thalassemia is one of the most frequently occurring hematological disorders in [Removed for blinded peer-review]. Regular blood transfusion is required in almost all cases for management. However, this is associated with significant major complications like red blood cell (RBC) alloimmunization. This retrospective cross-sectional is conducted to evaluate the RBC alloimmunization frequency in children with beta-thalassemia aged between 6 months and 16 years in [Removed for blinded peer-review]. Antibody screening was performed using the Dia clon3 cell antigen panel. If the screening came back positive, a detailed panel was created for the identification of specific antibody. In our sample, the frequency of RBC alloimmunization was found in 22 (26.19%) patients. Of these 22 patients, the Rhesus system was found in most patients 17 (77.3%), followed by Kell 5 (22.7%). RBC alloimmunization was significantly associated with a family history of a blood disorder and splenectomy.

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.

The value of transfusion of phenotyped blood units for thalassemia and sickle cell anemia patients at an academic center

BACKGROUND

Blood transfusion is the first-line treatment for patients with thalassemia and many sickle cell patients. However, cases of unregulated blood transfusion are shown to carry a high risk of alloimmunization to red blood cells (RBCs), which can lead to a hemolytic transfusion reaction and be fatal to patients. Screening and identification of alloantibodies are, therefore, essential practice in blood transfusion services. Transfusion of phenotyped blood can minimize these risks to patients.

STUDY DESIGN AND METHODS

A prospective study was carried out on 1015 donors, and a prospective and retrospective study was carried out on 208 multiple transfused patients with β-thalassemia and sickle cell anemia. Donor and patient samples were subjected to Rh & K typing, and patient samples were also subjected to screening & identification of RBC antibodies. We aimed to determine the prevalence of RBC antigens in thalassemia and sickle cell patients, as well as blood donors, at King Abdulaziz University Hospital and the frequency of alloimmunization in the selected patients.

RESULTS

The most commonly detected Rh-phenotype in donors was R1r (32.02%), followed by R1R1 (23.25%). Only 9.16% of donors were positive for the K antigen. The prevalence of Rh and K blood group antigens was also reported: the highest detected Rh-phenotype was R1r (40.86%) followed by R1R2 (24.04%) with only (6.25%) positive patients for K antigen. The rate of alloimmunization among sickle cell anemia and thalassemia patients was 39.42% and 35.57%, respectively. The highest specificity rates of the alloantibodies were recorded for anti-E and anti-K in both patient groups.

CONCLUSION

The rate of alloimmunization in transfused patients was high and particularly observed against the Rh and K antigens. This study emphasizes the clinical need for typing patient RBCs prior to transfusion so as to provide phenotyped matched blood units and minimize the risks and associated morbidities of alloimmunization. Keeping a database of phenotyped blood donors is essential for the clinically effective and safe management of transfusion 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.

The future of voluntary blood donation in the Kingdom of Saudi Arabia

Replacement blood donations are a major source of blood in KSA. This presentation highlights "the peace time and war experiences," where the voluntary donor potential was tested. THE "PEACETIME EXPERIENCE"-KING SAUD UNIVERSITY STUDENT DONOR DRIVE: This donor drive commenced in 1983 with 13 donors in its first and the annual collection reached 4500 blood units in the academic session 1995-1996, when the student enrollment was around 30,000. In 2018 the enrollment jumped to 120,000 students. If we add the staff and auxiliary personnel, the population of potential voluntary blood donors will be enough to cover the current and future blood needs of King Khalid University Hospital. Unfortunately, this drive did not survive due to administrative and organizational difficulties. THE "FIRST" GULF WAR EXPERIENCE: At the end of 1990, when the Allied Forces started to end the Iraqi occupation of Kuwait, the Saudi Ministry of Health waged a publicity campaign asking healthy individuals to donate their blood. The response was phenomenal, and the blood inventory in blood banks swelled about five- to sevenfold. First-time donors broke the "fear barrier," went through the donation experience, and it is hoped they will return to donate voluntarily. CONCLUSIONS: The major lesson learned from the King Saud University student donor drive and Gulf War experience is the enormous voluntary donor potential in Saudi Arabia. There is a need for forward planning to shift the current partial involuntary donor system to a voluntary system based on nonremunerated donors.

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.

Alloimmunization in Patients with Sickle Cell Disease and Thalassemia: Experience of a Single Centre in Oman

Background

Blood transfusion is an integral part of the supportive care for patients with sickle cell disease (SCD) and thalassaemia. The hazard of red cell alloimmunization, however, is one of the main complications of this therapy.

Objectives

The aim of this study was to evaluate the prevalence of red cell alloimmunization in Omani patients with sickle cell anaemia and thalassemia.

Methods

This study included 262 patients whose historical transfusion records were available. One hundred and twenty-nine patients with thalassaemia who were attending the day care unit for regular transfusions, and 133 SCD patients admitted at our hospital were included in this study. The Diamed® gel system was used for the screening and identification of atypical antibodies.

Results

The rate of alloimmunization in SCD patients was 31.6% (n=42, 95%CI, 24.87–40.66), whereas in patients with thalassaemia it was 20% (n=26; 95%CI, 13.9–27.6). Antibodies to E, e, C, c, D, K, S, Fyª, Kpª, Jkª and C^w were observed; 85% of the patients were also immunised with Rh and Kell antigens. Considering the two groups together, 8 developed nonspecific antibodies and 12 developed more than one antibody.

Conclusions

Red cell transfusions were associated with a significant risk of alloimmunization. It is, therefore, imperative to perform an initial extended red cell phenotyping for both donors and recipients, and carefully select ABO, Rh and Kell matched donors. The higher incidence of alloimmunization in SCD patients is related to the inherent SCD-specific inflammatory state.

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.

Frequency of Red Cell Alloimmunization and Autoimmunization in Thalassemia Patients: A Report from Eastern India

Introduction. Red blood cell (RBC) alloimmunization and autoimmunization remain a major problem in transfusion dependent thalassemic patients. There is a paucity of data on the incidence of RBC alloimmunization and autoimmunization in thalassemic patients from eastern part of India, as pretransfusion antibody screening is not routinely performed. Aims. To assess the incidence of RBC alloimmunization and autoimmunization in transfusion dependent thalassemic patients in eastern India. Materials and Methods. Total 500 thalassemia cases were evaluated. The antibody screening and identification were performed with commercially available panel cells (Diapanel, Bio-rad, Switzerland) by column agglutination method. To detect autoantibodies, autocontrol and direct antiglobulin tests were carried out using polyspecific coombs (IgG + C3d) gel cards in all patients. Results. A total of 28 patients developed RBC alloimmunization (5.6%) and 5 patients had autoantibodies (1%). Alloantibody against c had the highest incidence (28.57%) followed by E (21.42%). Five out of 28 (17.85%) patients had developed antibodies against both c and E. Conclusion. Data from this study demonstrate that the RBC alloantibody and autoantibody development rates are significant in our region. Thus, pretransfusion antibody screening needs to be initiated in eastern India in order to ensure safe transfusion practice.

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.

Risk factors for alloimmunisation in the general patient population

For hospitals providing services to regional populations, difficulties are associated with transferred patients with poorly communicated medical history and a risk of alloimmunisation. Identification of patients at risk would assist in treatment planning. A retrospective study of alloimmunised patients was undertaken, comparing the demographics and diagnoses of this population with a control patient population. A preponderance of diagnoses of Sepsis, Haematological Malignancy, GIT Bleeds and Renal Failure was demonstrated in the alloimmunised population. Consistent with prior studies, RhD negative patients and female patients were over-represented in the study group, which was also on average significantly older.

Multidisciplinary Care in Haemoglobinopathies

While most complications are related to haemoglobinopathies and their treatment, it is also possible to observe substantial differences in comorbidities’ onset and seriousness which depend also to the different HPs genotypes. These differences should be carefully considered when health authorities set up and manage adequate care systems and treatments plans. We describe services organisation in Italy including the availability of multispecialty care and tools, in the HPs units participating to the HTA-THAL Multiregional Registry, with the aim to derive the impact of the services and multispecialty care availability on the management of the disease and on the patients wellbeing. The high dispersion and heterogeneity of services demonstrated, exposes the Italian system to a high risk of: (a) inappropriate use of economical and medical resources, (b) limited access to multidisciplinary care of some patients with apparent inequality among different centres, and (c) low patients satisfaction with the services provided. The identification of a ‘standard for HPs services’ is necessary not only at national but also at interventional level in order to implement collaborative research and the identification and networking of reference’ centres worldwide. Following the big efforts provided in the last years here there is a new challenging mission for the TIF.

[Anti-erythrocyte and anti-HLA immunization in hemoglobinopathies]

AIM

Evaluate the anti-erythrocyte and anti-HLA immunization rates in hemoglobinopathies.

PATIENTS AND METHODS

Cross-sectional study (October 2009-March 2010) on 83 patients followed for hemoglobinopathies. The irregular antibodies research is realized by two techniques: indirect Coombs and enzymatic technique on gel cards. The search for anti-HLA class I antibodies is done by complement dependent lymphocytotoxicity.

RESULTS

The mean age was 30 years (14-64 years), the sex ratio M/F is 0.84. Our series included 42 cases of sickle cell disease (29 homozygous sickle cell anemia and 13 sickle-thalassemia) and 41 cases of thalassemia syndromes (26 major and 15 intermediate). The anti-erythrocyte alloimmunization rate is 10.84% without difference between thalassemia syndromes and sickle cell disease. The autoimmunization rate (22.89%) is higher in thalassemia syndromes (41.46%) than in the sickle cell disease (7.14%) (P<0.001). The anti-HLA immunization rate is 31.6% without difference between thalassemia syndromes and sickle cell disease. The young age, transfusion at a young age and the total number of transfusions are the factors that increase the risk of anti-erythrocyte autoimmunization. No clinicobiological parameter does influence the anti-erythrocyte and anti-HLA alloimmunization. There is no significant association between anti-erythrocyte and anti-HLA immunization.

CONCLUSION

The erythrocyte and anti-HLA anti-immunization rates are high in our series. Preventive strategy is needed to ensure optimal blood safety.

Beta thalassemia major in a developing country: epidemiological, clinical and evolutionary aspects

Beta-thalassemia major (TM) remains to be one of the major health problems particularly in developing countries. Tunisia is a part of the Mediterranean countries mostly affected by this disease which is highly concentrated in small towns in families with low-income earners. The main objectives of this study are to provide a description of the demographic, clinical features and transfusion-related complications in patients with TM living in Tunisia. A standardized questionnaire was sent to clinicians throughout 33 different medical institutions caring for thalassemic patients. 391 transfusion dependant thalassemic patients with a median age of 10.7 years (range 3 months- 31 years) were included in the study. The majority originated from the north west of the country. A moderate iron overload between 1501 and 2500 ng/ml was found in 61patients, while 81 patients (26.9%) had a ferritin level more than 2500 ng/ml and greater than 5000ng/ml in 21 patients (6.9%). 51 patients died from complications related to their disease. Heart failure was the main cause of death. The incidence of cardiac, endocrine, and infectious complications will be reviewed. Preventive measures such as health education, carrier screening and premarital screening remain the best ways for lowering the incidence of these diseases, which might be reflected in financial saving, social s and health benefits.

[Red blood cell immunization in haemoglobinopathie: about 84 cases]

AIMS

To estimate the rate of red cell immunization in hemoglobinopathies.

PATIENTS AND METHODS

Prospective study (1990-2009) about 84 patients: 44 homozygous sickle cell anemia, one heterozygous sickle cell anemia S/C, 30 thalassemia and nine sickle cell anemia-thalassemia. The mean age was 10.13 years (extremes: 1-45). The red cell units transfused were ABORH1 compatible, then RH-KELL phenotyped after 2006 and phenocompatible after alloimmunisation. The cross-match was realized using indirect antiglobuline test. Irregular red cell antibody screening was realized before every transfusional episode and the direct antiglobuline test was done when there was a poor transfusional efficiency.

RESULTS

The number of red blood cells units transfused was 3545 (42.2/patient). The number of red cell antibody screening and the number of direct antiglobulin test were respectively 1474 (17.5/patient) and 272 (3.2/patient). Twenty-seven antibodies were identified (32.1%): 14 alloantibodies (16.6%, 16.6% in sickle cell disease, 16.6% in thalassemia, P=1), 16 antoantibodies (19.04%, 11.1% in sickle cell disease, 33.3% in thalassemia, P=0.018). There were three cases of association of allo- and autoantibodies. The most frequent alloantibodies were anti-RH3 and anti-KEL1 and were developed after transfusion of standard red cell units. There was no significant relation, neither between sex and risk of immunization, nor between the number of red cell units transfused and alloimmunization. On the other hand, there was a significant relation between autoimmunization and the number of red cell units transfused in thalassemia (P<0.001).

CONCLUSION

This study proves the interest of using RH-KELL red cell units compatible in patients with hemoglobinopathies in order to reduce alloimmunisation rates.

Challenges of alloimmunization in patients with haemoglobinopathies

Red blood cell (RBC) transfusions can be life-sustaining in chronic inherited anaemias, such as thalassaemia, and the indications for blood transfusions in patients with sickle cell disease continue to expand. Complications of transfusions, such as allosensitization, can create significant medical challenges in the management of patients with haemoglobinopathies. This review summarizes key findings from the medical literature related to alloimmunization in haemoglobinopathies and examines potential measures to mitigate these risks. Areas where future studies are needed are also addressed.

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 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.

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.