Phenotyping Rh/Kell and risk of alloimmunization in haematological patients

Transfusion of packed red blood cells in adults with sickle cell anemia treated at an emergency hospital

OBJECTIVE

The aim of this study was to analyze the prescription of packed red blood cells performed by emergency physicians for adults with sickle cell anemia.

METHODS

Transfusions performed in adults with sickle cell anemia treated at an emergency service in São Bernardo do Campo, São Paulo Brazil, between January 2018 and January 2022 were evaluated. For data comparison, the chi-square2 test was used. The significance level adopted was 5%.

RESULTS

A total of 114 transfusions were performed. The mean age was 41.8±16.4 years, and pretransfusion hemoglobin was 6.1±1.23 g/dL. Regarding the indication, the adequacy of transfusions performed in symptomatic individuals was significantly higher compared to asymptomatic individuals (100% vs. 3.9%, p<0.001). Symptomatic individuals received excessive volumes of packed red blood cells less frequently than asymptomatic individuals (17.5% vs. 56.9%, p<0.001). The filtered subtype, indicated for sickle cell anemia, was prescribed in only a quarter of the patients. However, non-indicated subtypes were frequently prescribed.

CONCLUSION

This study found low adequacy in the indication and calculation of the transfusion volume of packed red blood cells in asymptomatic individuals. Few patients received filtered red blood cells, resulting in increased risks of transfusion reactions. On the contrary, non-indicated subtypes were prescribed in a quarter of transfusions, which resulted in higher costs and delay in receiving packed red blood cells.

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 transfusion in myelodysplastic syndromes: A systematic review

Patients with myelodysplastic syndrome (MDS) frequently receive red blood cell (RBC) transfusions for anaemia resulting from ineffective erythropoiesis. While RBC transfusions may rapidly increase haemoglobin values, their impact on clinical and health services outcomes in MDS patients has not previously been summarized. We conducted a systematic review of the literature to evaluate risks and benefits of RBC transfusions in MDS patients. We searched electronic databases (MEDLINE, Embase, CENTRAL, CINAHL) from inception through June 4, 2021 to identify studies reporting data on RBC transfusions in MDS patients. Full text publications that assessed RBC transfusions as an intervention and reported at least one clinical, laboratory, or healthcare outcome associated with transfusion were included. Study characteristics, transfusion information and transfusion-related outcomes were extracted and reported. We identified 1243 original studies, of which 38 met eligibility requirements and were included. Fourteen reported on survival following diagnosis of MDS, with the majority reporting poorer survival among patients receiving or requiring more frequent transfusions. Nine reported on transfusion-related iron overload and its complications. Other outcomes included rates of allo/autoimmunization and adverse transfusion reactions, and healthcare costs incurred by patients with a greater transfusion burden. Only two studies reported on symptom relief following transfusion. This review underscores transfusion dependence as a negative prognostic factor for MDS patients and highlights the paucity of evidence surrounding quality of life and symptom-related outcomes following RBC transfusions in this population. Further study of patient-important outcomes associated with transfusion in MDS patients is warranted to improve therapeutic recommendations and inform resource allocation.

An Easy Multiplex PCR-SSP Assay for the Genotyping of KEL1 and KEL2 in Multi-transfused Patients

Kell blood group system consists of 34 antigens. KEL1 and KEL2 are the most clinically important antigens of this system, causing hemolytic disease of the fetus and newborn (HDFN) and transfusion reaction. A total of 200 samples from blood donors were tested serologically for the presence of KEL1 and KEL2 antigens on erythrocytes. Genomic DNA was analyzed by PCR-SSP method to determine the Kell genotype. A multiplex PCR-SSP assay was designed and tested to genotype KEL1/KEL2 alleles in a single reaction. PCR genotyping revealed samples as; KEL2/KEL2 (93.5%) and KEL1/KEL2 (6.5%), while no sample determined as KEL1/KEL1. A 100% concordance observed between PCR and serological results. Multiplex PCR accurately diagnosed Kell genotype. Kell blood group genotyping by PCR-SSP can be used as an alternative method, especially in multi-transfused patients where serological findings are ambiguous.

RBC alloantibody prevalence and specificity in a Western Norwegian tertiary hospital

BACKGROUND AND OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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