IntroductionPre-transfusion tests, essential for the release of blood components, may be affected by drugs. Monoclonal antibodies represent a class of medications increasingly used in the clinical practice, with anti-CD38 monoclonal antibodies (daratumumab) being a promising resource in the treatment of refractory myeloma. This monoclonal antibody recognizes CD38 in myeloma cells and interferes with pre-transfusion tests by causing panreactivity in indirect antiglobulin tests thereby clinically masking alloantibodies. Dithiothreitol is a reagent that breaks disulfide bonds and effectively destroys antigenic sites for CD38 on red blood cells. This study reports the immunohematological findings of pre-transfusion tests of patients with multiple myeloma receiving daratumumab and on solutions to prevent the interference of this monoclonal antibody.MethodsSerum samples from five patients on anti-CD38 monoclonal antibody treatment were evaluated. Tests performed included ABO/RhD typing, indirect antiglobulin test, direct antiglobulin test and eluate test. A daily evaluation was performed to determine the shelf life of dithiothreitol-treated red blood cells when stored in Alsever's solution.ResultsNo interference in the ABO/RhD typing results was noted but in all samples, a panreactivity was observed in indirect antiglobulin tests. Regarding the direct antiglobulin test, two samples presented positive results but negative eluates. In all samples, treatment of reagent red blood cells with 0.2 M dithiothreitol offset interference by anti-CD38 monoclonal antibodies. Dithiothreitol-treated red blood cells stored in Alsever's solution were stable for up to 15 days.ConclusionTreatment of reagent red blood cells with dithiothreitol can be efficient and accessible to offset the interference of the anti-CD38 drug in pre-transfusion tests. The number of costly serological workups can be reduced by having stored dithiothreitol red blood cells with this proving to be a useful reagent for investigating anti-CD38.

BackgroundOne of the strategies used to reduce the risk of haemolysis due to ABO‐minor incompatible platelet transfusions is to perform a screening test to identify group O donors with high titres of anti‐A and anti‐B. However, critical immunoglobulin M/ immunoglobulin G (IgM/IgG) titres remain unclear.ObjectiveThis study aimed to determine IgM titres of anti‐A and anti‐B in individual donor serum vs platelet products plasma and identify a possible association between IgM/IgG titres, haemolysin test and IgG subclasses in Brazilian blood donors from group O.MethodsIgM anti‐A and Anti‐B titration tests were performed on single‐donor serum and platelet product plasma by gel agglutination (GA) at room temperature. For IgG anti‐A and anti‐B titration, serum was first treated with 0.01 M dithiothreitol (DTT), and the test was performed by GA with incubation at 37°C. Dilution of 1:64 as the cut‐off was considered for both IgM/IgG. The qualitative haemolysin test was performed in tube, adding AB fresh serum, with incubation at 37°C. IgG subclasses were determined by GA using specific monoclonal antibodies.ResultsAn association between anti‐A and anti‐B IgM titres and haemolysin were demonstrated (P < .001). IgM titres in plasma samples from platelet components correlated to those in single‐serum samples. IgG1/IgG3 subclasses were associated with total haemolysis and titres above 64, whereas IgG2/IgG4 subclasses were associated with the absence of haemolysis and titres below 64 (P < .001).ConclusionOur data suggest that a value of 64 as a critical titre can be used as a screening test of anti‐A and anti‐B IgM to prevent transfusion reactions. This can be a safe and cost‐effective approach for managing ABO‐incompatible platelet transfusions.

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The correct identification of erythrocyte antibodies is fundamental for the searching for compatible blood and haemolytic transfusion reactions prevention. Antibodies against antigens of high prevalence are difficult to identify because of the rarity of their occurrence and unavailability of negative red cells for confirmation. We report a case of 46-years-old woman, diagnosed with hemoglobinopathy, and who had symptomatic fall in hemoglobin levels (5.3g/dL) after blood transfusion suggestive of transfusion reaction. The patient’s blood type was O RhD-positive. Irregular antibody screening was positive and demonstrated a panreaction against all erythrocytes tested, but this result was not reactive with dithiothreitol. Using negative red cells for antigens of high prevalence of our inventory we could identify in the serum of the same erythrocytes an anti-Holley antibody associated with anti-E. Molecular analysis confirmed that the patient was negative for E and Holley antigens. The crossmath with compatible units confirmed the results. Holley is a high prevalence antigen of the Dombrock blood system whose negative phenotype is extremely rare in all populations and is associated with hemolytic transfusion reactions. This is an antibody that is difficult to identify because laboratories need to have experience in solving complex cases, and have available a large stock of rare sera and erythrocytes, as well other tools such as enzymes, thiol reagents and molecular tests. The correct identification of a rare antibody is initial and mandatory for searching of compatible donors, and to guarantee a satisfactory transfusional support.

Objective To described the allele and haplotype frequencies of human leukocyte antigen genes at the -A, -B loci and human platelet antigen genes for human platelet antigen systems 1 to 9, 11 and 15 in blood. Methods We included 867 healthy unrelated volunteer donors who donated platelets between January 2011 and December 2014. Microarray genotyping was performed using a BeadChip microarray. Medium resolution typing of the human leukocyte antigen at loci A and B was carried out using sequence-specific oligonucleotide probe hybridization. We used multivariate analysis and our human leukocyte antigen population was compared to data from the United States national bone marrow donor program. Human platelet antigen results were compared to a literature review and data from around the world. Results Our human leukocyte antigen haplotype results were more similar to those of hispanics, followed by caucasians. Likewise, our human platelet antigen sample is more similar to those of Argentina, Rio Grande do Sul and Italy. Conclusion This was the first article that discusses human platelet antigen and human leukocyte antigen data together. Rare genotypes or antibody associations can make patient management difficult. A blood bank with genotyped donors allows for optimal transfusion and can contribute to better results. Our information can serve as basis for a database of platelet antigen polymorphisms.