Clinical outcome of transfusions with extended red blood cell matching in β-thalassemia patients: A single-center experience

Investigation of variables affecting the immunogenicity of blood group antigens using a calculation formula

Previous studies on the immunogenicity of blood group antigens have utilized a formula incorporating antigen frequencies and relative frequencies of unexpected antibodies to the corresponding antigens. This study was aimed at investigating other variables potentially affecting the estimation of immunogenicity using this formula. We examined the effect of multiple transfusions, as there are more chance for a recipient to receive repeated transfusions rather than only once; the effect of antigen density, which may vary depending on homozygote/heterozygote; and the effect of unreliability of the observed frequency of rare antibodies and antigens. For multiple transfusions, the expected antibody frequency increased as the number of transfusions increased. For antigen density, the immunogenicity was falsely low for the low-prevalence antigen, and this tendency intensified as the effect of antigen density increased. Expected antibody frequencies were significantly affected by the uncertainties caused by estimation of small numbers. This study showed that the effects of various factors on the immunogenicity of blood group antigens depended on the antigen frequency. Estimating the immunogenicity of blood group antigens requires acknowledging the diverse factors that can affect it and interpreting the findings with caution.

Somatic mutations show no clear association with red blood cell or human leukocyte antigen alloimmunization in de novo or therapy-related myelodysplastic syndrome

BACKGROUND

Myelodysplastic syndrome (MDS) is a marrow failure disease. As patients often require chronic transfusion, many develop red blood cell (RBC) alloimmunization or immune-mediated platelet refractoriness. MDS represents a spectrum of diseases with specific categorizations and genetic abnormalities, and we set out to determine if these characteristics predispose patients to antibody formation.

STUDY DESIGN AND METHODS

A natural language search identified MDS patients with pre-transfusion testing from 2015 to 2020. Marrow reports, cytogenetic results, and next-generation sequencing panels were gathered. Transfusion history and testing were collected from the laboratory information system.

RESULTS

The group consisted of 226 biopsy-proven MDS patients. The prevalence of RBC alloimmunization was 11.1% (25 of 226). Half (23 of 46) of all RBC alloantibodies were against Rh (C, c, E, e) and Kell (K) antigens. There was a relative enrichment for JAK2 positivity among the RBC alloimmunized group. A total of 7.1% (16 of 226) of patients had immune-mediated platelet refractoriness and had increased transfusion requirements (p ≤ 0.01). No disease type or genetic abnormality was significantly associated with alloimmunization or immune-mediated platelet refractoriness.

DISCUSSION

While JAK2 specific mutations were enriched among RBC alloimmunized patients, this association failed to reach statistical significance in our single-center cohort. Further study using larger patient cohorts is warranted. Overall, this cohort of MDS patients had very similar RBC alloimmunization prevalence and anti-RBC antibody specificities as other recent literature. Our data reinforce the finding that MDS patients are at greater risk for alloimmunization and support the use of extended phenotype matching for these at-risk patients.

Red blood cell alloimmunization and other transfusion-related complications in patients with transfusion-dependent thalassemia: A multi-center study in Thailand

BACKGROUND

Thalassemia is a common genetic disease in Southeast Asia. Red blood cell (RBC) transfusion is an essential treatment for severe forms of thalassemia. We performed a study to demonstrate RBC alloimmunization and other transfusion-related complications in patients with transfusion-dependent thalassemia (TDT).

STUDY DESIGN AND METHODS

A multi-center web-based registry of TDT was conducted in eight medical centers across Thailand. Thalassemia information, transfusion therapy, and transfusion-related complications were collected. Factors associated with each complication were demonstrated using the logistic regression analysis.

RESULTS

Of 1000 patients recruited for the study, 449 were males (44.9%). The mean age was 23.9 ± 15.4 years. The majority of patients, 738 (73.8%) had hemoglobin E/beta-thalassemia. In the study, 421 transfusion-related complications were reported from 357 patients (35.7%). Alloimmunization was the most common complication which was found in 156 patients (15.6%) with 284 positive antibody tests. The most frequent antibodies against RBC were anti-E (80/284, 28.2%) followed by anti-Mia (45/284, 15.8%) and anti-c (32/284, 11.3%). Age ≥3 years at initial blood transfusion, splenomegaly, higher frequencies, and volumes of transfusion were significant factors associated with alloimmunization. None of the patients had to terminate blood transfusion due to multiple alloantibodies. Other commonly seen complications were allergic reactions (130, 13.0%), autoimmune hemolytic anemia (70, 7.0%) and febrile non-hemolytic transfusion reaction (54, 5.4%).

CONCLUSIONS

Transfusion-related complications, especially alloimmunization, were common among Thai patients with TDT. Extended RBC antigen-matching for the Rh system and Mia should be implemented to prevent the development of alloantibodies in multi-transfused patients.

Relative immunogenicity of blood group antigens: First report in a Korean population

BACKGROUND

The immunogenicity of a blood group antigen is a measure of its likelihood of inducing alloantibodies. Although the immunogenicity of blood group antigens has been analyzed in Caucasian populations, immunogenicity to date has not been analyzed in Asian subjects. The present study therefore evaluated the relative immunogenicity of blood group antigens in a Korean population.

STUDY DESIGN AND METHODS

All available data of unexpected antibody identification tests performed at Asan Medical Center between 1997 and 2021 were analyzed. The relative immunogenicity of a blood group antigen relative to K antigen was calculated based on relative numbers of alloantibodies and the probabilities of antigen-negative recipients receiving antigen-positive RBC units.

RESULTS

A total of 3898 antibody identification results were included, with 1632 (41.9 %) from male patients. The ranking of antigen immunogenicity was: E > c > e > C > K > Jk(a) > Lu(a) > S > Fy(a) > Fy(b) > Jk(b) > Di(b) > Di(a) in the total population and E > c > e > C > Jk(a) > Fy(a) > Fy(b) > S > K > Lu(a) > Jk(b) > Di(b) > Di(a) in male patients.

DISCUSSION

The rank order of immunogenicity for blood group antigens in this study provides information about relative immunogenecity in Koreans. These findings also provide supporting evidence regarding antigen selection for extended antigen-matched transfusions in recipients of multiple transfusions.

Luspatercept, a two-edged sword in beta-thalassemia-associated paravertebral extramedullary hematopoietic masses (EHMs)

Paravertebral extramedullary hematopoietic masses (EHMs) account for up to 15% of extramedullary pseudotumors in beta-thalassemia (BT) and are most likely related to compensatory hematopoiesis. In most cases, pseudotumors are incidentally detected, as the majority of patients are asymptomatic. Since June 2020, luspatercept is approved for the treatment of patients with BT who require regular red blood cell transfusions. Data addressing the safety and efficacy of luspatercept in patients with BT-associated EHMs are pending. To date (May 2022), paravertebral EHMs were observed in two asymptomatic patients out of currently 43 adult patients with BT registered at the Adult Hemoglobinopathy Outpatient Unit of the University Hospital Essen, Germany. In one of them, a paravertebral EHM was diagnosed for more than 10 years prior to referral. Throughout observation time, treatment with luspatercept was associated with a clinically significant reduction in transfusion burden while allowing to maintain a baseline hemoglobin concentration of ≥10 g/dl aiming to suppress endogenous (ineffective) erythropoiesis associated with BT. Considering the rarity of paravertebral EHMs in BT, luspatercept might potentially represent a novel therapeutic option for these often-serious disease-associated complications. However, appropriate follow-up investigations are recommended to detect (early) treatment failures secondary to an undesired luspatercept-associated erythroid expansion.

Comprehensive management of refractory autoimmune hemolytic anemia in pediatric beta-thalassemia major patient: A case report

Introduction

and importance: Autoimmune hemolytic anemia (AIHA) is characterized by the production of antibodies against the red blood cells (RBCs) leading to increased hemolysis. Incidence of AIHA in patients with beta-thalassemia major is 5 of 100 thalassemia patients.

Case presentation

A 15-year-old female patient with refractory AIHA and thalassemia was unresponsive to steroid therapy. In this report, she was treated with cyclosporine and prednisone in addition to leucodepleted packed red cell (PRC). She was successfully got remission during one-year monitoring.

Clinical discussion

Cyclosporine is an immunosuppressive agent that interferes with T-cells activation by inhibiting transcription of cytokines, such as interleukin 2 and interferon-ɣ. Cyclosporine and steroid have synergic effects to prevent antibody production. Nephrotoxicity is one of the most concerning effect in cyclosporine usage, but it rarely develops using doses lower than 5 mg/kgBW/day. In limited resources blood bank with ABO and Rh crossmatch only, leucodepleted PRC transfusion could be an effective way to prevent antibody formation to minor blood group.

Conclusion

Cyclosporine and steroid could be considered for management in refractory AIHA with thalassemia patients. Non-pharmacological therapy such as leucodepleted PRC transfusion and limited donor transfusion could be considered.

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Cyclosporine and steroid may be of benefit in patients with refractory AIHA and beta thalassemia major.

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Leukodepleted PRC transfusion showed protective effect for antibody formation.

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Limited donor transfusion could be beneficial in recurrent transfusion patient.

Genotyping versus phenotyping of non-ABO erythrocyte antigens in patients with the Mediterranean hemopathic syndromes: Effect of transfusion therapy

The Mediterranean hemopathic syndromes (MHS) are the most prevalent hemoglobinopathies in the Mediterranean basin. Transfusion therapy is the main therapy for these disorders, particularly for severe forms of the disease. Currently, pre-transfusion serological typing of erythrocyte antigens is the standard tool for reducing complications of transfusion in those patients. This study compared genotyping with phenotyping of non-ABO erythrocyte antigens in patients with MHS and assessed the effect of transfusion therapy on their results. One-hundred ninety-eight MHS patients were recruited, screened, and proven negative for allo-antibodies. They were grouped into two groups: (1) 20 newly diagnosed patients with no transfusion history and (2) 178 previously diagnosed patients undergoing transfusion therapy. Patients were interviewed and clinically examined. Full blood count (FBC) and high performance liquid chromatography (HPLC) were done for group 1 only. Genotyping and phenotyping of non-ABO erythrocyte antigens were performed for group 1, and 25 patients out of group 2 were propensity score-matched (PSM) with group 1. Both groups were gender and age matched; 55% and 74% of groups 1 and 2 had major disease, respectively. Insignificant differences were observed between genotyping and phenotyping of non-ABO erythrocyte antigens in group 1, while significant discrepancies and mixed field results were noted in group 2 patients. Discrepancies were obvious with JK^a, JK^b, and little c antigens. Conclusively, molecular typing is a powerful tool for pre-transfusion testing in chronically transfused MHS patients. This testing reduces incidence of transfusion reactions. JK^a, JK^b and little c antigens are the most clinically significant non-ABO erythrocyte antigens.

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.

Red-blood-cell alloimmunization and prophylactic antigen matching for transfusion in patients with warm autoantibodies

BACKGROUND

Warm autoantibodies (WAA) are antibodies that react with an antigen on a patient's own red-blood-cells and can complicate compatibility testing whether or not they cause clinical haemolysis. The goal of this study was to understand the overall prevalence of WAA, the risk of RBC alloimmunization and determine whether RBC selection practices have an impact on alloimmunization.

MATERIALS AND METHODS

Records of patients (>1 year of age) with an indirect antibody detection test (IAT) and serologic evidence of WAA over a 10-year-period were included. Eight centres from 5 countries collectively reviewed 1 122 245 patients who had an IAT.

RESULTS

Of patients having IAT, 1214 had WAA (0·17%). Transfusion information for 1002 of the patients was available; 631 were transfused after identification of the WAA (63%); of the transfused patients, 390 received prophylactic antigen-matched (PAM) RBCs and 241 did not. Of the 372 patients with WAA who were transfused and had serologic testing 30+ days following transfusion (30-2765 days), 56 developed new RBC alloimmunization (15·1%). Patients who were transfused using a PAM strategy were not protected from new RBC alloimmunization [14·6% (31 of 212 patients) having PAM transfusion approach compared with those not receiving PAM approach (15·6%, 25 of 160 patients, P = 0·8837)].

CONCLUSIONS

The prevalence of WAA in patients having an IAT is low (<1%). A significant portion of patients with WAA form new RBC alloimmunization (15·1%); however, the use of PAM approach for RBC selection was not found to be protective against new alloimmunization.

Adverse transfusion reactions in transfused children

Transfusion in paediatrics requires specific guidelines, because child physiology and pathology differ significantly as compared to adults. Adverse transfusion reactions in transfused children also vary in type and frequency, but there is a better understanding of these reactions in adults than in children. However, for the most frequent adverse transfusion reactions, the overall prevalence is higher in children than in adults, with the exception of post-transfusion red blood cell alloimmunisation, which is lower, excluding patients with haemoglobinopathies. In several studies, allergic reactions were the most frequently reported adverse transfusion reaction in paediatrics, and the platelet concentrate the most frequently implicated blood product. Early diagnosis of certain adverse transfusion reactions such as haemosiderosis, is essential in order to initiate the best therapy and obtain a good clinical outcome. The prevention of adverse transfusion reactions in children is required, but needs further clinical studies in paediatrics. Lastly, changes in technology, policy and clinical practices will improve transfusion safety in children.