The impact of an antibody investigation algorithm emphasizing specificity on reducing potential false-positive warm autoantibody detection at a Canadian tertiary care centre.

BACKGROUND AND OBJECTIVES: To reduce potential false-positive warm autoantibody (WAA) by solid-phase red cell adherence assay (SPRCA), our centre implemented a new antibody investigation algorithm (AIA) by classifying cases with panreactive SPRCA but negative saline-indirect antiglobulin test as 'antibody of undetermined significance' (AUS) after excluding clinically significant antibodies. We assessed the effects of the new AIA and subsequent alloantibody formation in patients with AUS. MATERIALS AND METHODS: Samples from patients with positive SPRCA screens between 1 September 2017 and 31 August 2021 were selected for the study. Frequencies of antibodies classified by the old and new AIAs were compared using Fisher's exact test. Patient demographics, transfusion history and antibody formation in cases of AUS were collected. RESULTS: A significant reduction in potential WAA frequencies from 127/1167 (11%) to 53/854 (6%) was observed (p < 0.001) when compared between the old and new AIAs among 2021 positive SPRCA antibody screens. While no patients with AUS later transitioned to potential WAA using the new AIA, four patients developed alloantibodies, including anti-E, anti-C, both anti-C and anti-E, and anti-Wra . CONCLUSION: A significant reduction in the frequencies of potential false-positive WAA detection at our centre was observed after implementing the new AIA, leading to less resource and phenotypically matched red blood cell (RBC) use. Some patients still developed subsequent RBC alloimmunization, so clinically relevant alloantibodies should be carefully excluded before determining AUS, taking forming or evanescent antibodies into consideration.

Diagnosis of severe anaemia and positive antibody screening as consequences of pre-analytical error.

The pre-analytical phase is the principal source of errors in laboratory medicine and continues to pose a challenge to laboratory professionals. We present the case of a 73-yearold female patient with a very low hemoglobin level (69 g/L) and positive indirect antiglobulin test result that indicates the key role of phlebotomy as an important error-prone process in which mistakes can have serious consequences for the patient's diagnosis and treatment. We conclude that there is still an urgent and continuous need to provide educational activities for healthcare professionals involved in blood collection, improve blood collection guideline adherence, and eliminate the errors which can affect diagnosis and treatment, thus jeopardising patient safety.

Strategies to overcome the diagnostic challenges of autoimmune hemolytic anemias.

INTRODUCTION: The direct antiglobulin test (DAT) or Coombs test is the cornerstone of the diagnosis of autoimmune hemolytic anemia (AIHA). It can be performed by several methods with different sensitivity and specificity and enables the distinction of warm, cold, and mixed forms, which require different therapies. AREAS COVERED: The review describes the different DAT methods, including the tube test with monospecific antisera, microcolumn and solid phase methods that are routinely accessible in most laboratories. Additional investigations include the use of cold washes and low ionic salt solutions, the identification of auto-Ab specificity and thermal range, the study of the eluate, and the Donath-Landsteiner test, available in most reference laboratories. Experimental techniques are the dual-DAT, flow cytometry, ELISA, immuno-radiometric assay, and mitogen-stimulated DAT, which may help the diagnosis of DAT-negative AIHAs, a clinical challenge with delayed diagnosis and possible improper therapy. Further diagnostic challenges include the correct interpretation of hemolytic markers, the infectious and thrombotic complications, and the possible underlying conditions (lymphoproliferative disorders, immunodeficiencies, neoplasms, transplants, and drugs). EXPERT OPINION: These diagnostic challenges may be overcome by a 'hub' and 'spoke' organization among laboratories, a clinical validation of experimental techniques, and a continuous dialogue between clinicians and immune-hematologic laboratory experts.

Mitigation of therapeutic anti-CD38 antibody interference with fab fragments: How well does it perform?

BACKGROUND: Administration of anti-CD38 antibodies is a state-of-the-art therapy for patients diagnosed with multiple myeloma (MM). However, this treatment frequently leads to pan-agglutination of red blood cells (RBCs) in patients' serological testing making accurate blood typing and timely transfusion of compatible blood a challenging effort. The antigen masking indirect antiglobulin test (AMIAT) is an approach to address this diagnostic challenge. STUDY DESIGN AND METHODS: A new reagent, called DaraEx plus, uses anti-CD38 Fab fragments to mitigate the anti-CD38 antibody interference in serological assays by masking CD38 on the cell surface. Its performance is extensively examined with commercial sera as well as with patient samples, and compared to the current standard method using dithiothreitol (DTT), which denatures the CD38 antigens on test panel erythrocytes. RESULTS: In the Bio-Rad ID System, DaraEx plus effectively mitigated the interference caused by anti-CD38 antibodies in 86% of patient samples tested while DTT was successful in only 68%. Moreover, there was no negative influence on DTT-sensitive blood group systems such as KEL upon DaraEx plus treatment. The agglutination reactions of all tested anti-CD38 antibodies (Daratumumab, Felzartamab, and Isatuximab) were inhibited by DaraEx plus. The treatment was successful only if DaraEx plus was added to the test cells before the sample. Some of the other gel card systems tested showed background reactions with DaraEx plus-treated cells. CONCLUSION: DaraEx plus treatment is straightforward and quick to perform. In the Bio-Rad ID System, it is superior to DTT treatment in the prevention of anti-CD38 antibody interference.

Autoantibodies against red blood cell antigens are common in a malaria endemic area.

Plasmodium falciparum malaria can cause severe anemia. Even after treatment, hematocrit can decrease. The role of autoantibodies against erythrocytes is not clearly elucidated and how common they are, or what they are directed against, is still largely unknown. We have investigated antibodies against erythrocytes in healthy adult men living in a highly malaria endemic area in Uganda. We found antibodies in more than half of the individuals, which is significantly more than in a non-endemic area (Sweden). Some of the Ugandan samples had a broad reactivity where it was not possible to determine the exact target of the autoantibodies, but we also found specific antibodies directed against erythrocyte surface antigens known to be of importance for merozoite invasion such as glycophorin A (anti-Ena, anti-M) and glycophorin B (anti-U, anti-S). In addition, several autoantibodies had partial specificities against glycophorin C and the blood group systems Rh, Diego (located on Band 3), Duffy (located on ACKR1), and Cromer (located on CD55), all of which have been described to be important for malaria and therefore of interest for understanding how autoantibodies could potentially stop parasites from entering the erythrocyte. In conclusion, specific autoantibodies against erythrocytes are common in a malaria endemic area.

Influence of immunohematological markers on severity of in vivo hemolysis in human warm autoimmune haemolytic anemia.

Autoantibody production in autoimmune haemolytic anemia (AIHA) is the result of the loss of self-immunological tolerance of the host. Here we investigated the various immunohematological markers that may influence the severity of in vivo hemolysis in warm AIHA (WAIHA). Complete direct antiglobulin test (DAT) evaluation and immunohematological characterization were performed in 247 patients of WAIHA following departmental protocols. Clinical and laboratory details of patients were obtained from patient file. The median age of WAIHA patients was 47 years with a female preponderance. Lymphoproliferative diseases were the major underlying causes of secondary WAIHA. The mean haemoglobin (Hb) and reticulocyte count (Retic) were 6.43 gm/dL and 7.58% respectively. Single autoantibody bound to red cells was investigated in 151 patients. The main IgG subclass was IgG1. Multiple autoantibodies like IgG+ C, IgG+IgA and IgG+IgA+C were found in 87 (35.2%) patients. Free autoantibodies were observed in 112 patients with a median indirect antiglobulin test (IAT) reactivity of 2+. Derangement of haematological and biochemical values was statistically significant with increase in DAT reactivity, presence of multiple autoantibodies on red cells, coating of red cells by IgG3 or multiple IgG subclass, higher DAT dilution and increasing IAT reactivity. We conclude that several important but simple immunohematological parameters may influence the degree of in vivo hemolysis in WAIHA. Since a set of common haematological and biochemical test determines the severity of in vivo hemolysis therefore a comprehensive clinical and immunohematological evaluation is advisable for a correct diagnostic and therapeutic workup of WAIHA.

Anti-Chido/Rodgers antibodies in a patient with infectious disease / Anticuerpos anti-Chido/Rodgers en paciente con enfermedad infecciosa

Introduction: Red cell alloimmunization is an immune response against foreign red cell antigens, usually occurring due to sensibilization in blood transfusions and pregnancies. The Chido (Ch) and Rodgers (Rg) antigens are present in about 96-98 percent of the population in general. Patients who have antibodies against antigens of high frequency in the population are a problem for transfusion medicine. Objectives: To describe the case of a patient diagnosed with AIDS and invasive cancer of the rectum with a recent hospitalization for lower gastrointestinal bleeding and anemia with the presence of anti-Ch and anti-Rg and the difficulties and solutions found for handling the case. Case presentation: Anti-Ch and anti-Rg have not been found to cause a hemolytic transfusion reaction (HTR) or hemolytic disease of the fetus and newborn (HDFN). However, the clinical presentation and laboratory findings including the immunohematological workups concerning the reaction are discussed, with a special emphasis on the benefit of identifying such an antibody and providing a compatible blood unit for transfusion support of the patient. Conclusions: When an antibody against a high-frequency erythrocyte antigen is identified in African or American-descent, anti-Ch or anti-Rg should be considered and that transfusion tests should not be delayed due to its clinical importance(AU)

Introducción: La aloinmunización de glóbulos rojos es una respuesta inmune frente a antígenos de glóbulos rojos extraños, que pueden ocurrir por sensibilización en transfusiones de sangre y embarazos. Los antígenos Chido (Ch) y Rodgers (Rg) están presentes en aproximadamente el 96-98 por ciento de la mayoría de la población. Los pacientes que tienen anticuerpos contra antígenos de alta frecuencia poblacional son un problema para la medicina transfusional. Objetivos: Describir caso de un paciente diagnosticado de AIDS y cáncer invasivo de recto con hospitalización reciente por hemorragia digestiva baja y anemia con presencia de anti-Ch y anti-Rg y las dificultades y soluciones encontradas para el manejo del caso. Presentación de caso: No se ha encontrado que Anti-Ch y anti-Rg causen reacciones hemolíticas transfusionales y enfermedad hemolítica del recién nacido. Sin embargo, se discuten la presentación clínica y los hallazgos de laboratorio, incluidos los estudios inmunohematológicos con respecto a la reacción, con especial énfasis en el beneficio de identificar dicho anticuerpo y obtener una unidad de sangre para transfusión que respalde al paciente con respecto a proporcionar una unidad compatible. Conclusiones: Cuando se identifica anticuerpos contra un antígeno eritrocitario de alta frecuencia, en afrodescendientes o americanos, se deben considerar Anti-Ch o anti-Rg y no retrasar las pruebas de transfusión por su importancia clínica(AU)

2-Mercaptoethanol (2-ME)-based IATs or Polybrene method mitigates the interference of daratumumab on blood compatibility tests.

OBJECTIVES: Treating red blood cells (RBCs) with dithiothreitol (DTT) is a wildly-recommended to overcome the interference of the daratumumab (DARA) with blood compatibility testing. Nevertheless, DTT can be hard to obtain in the clinical laboratory, while its use in routine practice may be time-consuming. In the following study, we explored the feasibility of using a commercial 2-mercaptoethanol (2-ME) working solution or the time-saving Polybrene method to mitigate DARA interference. METHODS: Antibody screening and cross-matching were performed using 2-ME or DTT-based indirect antiglobulin tests (IATs) and Polybrene method (with human IgG anti-E same IATs titer as DARA as positive control) on 37 samples. Most clinically important blood group antigens on RBCs were detected after treatment with 2-ME or DTT. RESULTS: Treating RBCs with 2-ME eliminates the DARA interference with the antibody screening or cross-matching; yet, K antigen is denatured during treatment. DARA does not interfere with antibody screening and cross-matching via Polybrene method, while 2+ agglutinations of anti-E antibody with the same titer (IATs method) as DARA could be observed in the positive controls via this method. CONCLUSION: 2-ME-based IATs or Polybrene method could replace DTT-based IATs to mitigate DARA interference.

A renewed understanding of anti-human globulin reagents: interference constraints using an optimization method in pretransfusion compatibility tests.

Anti-human globulin (AHG) reagents are widely applied in pretransfusion compatibility tests. The accuracy of detection with AHG reagents is mainly affected by irregular antibodies or cold agglutinins in blood samples, which are related to the human complement system. Although much has been written about various types and applications of AHG reagents, their characteristics, interference factors and optimal selection in pretransfusion compatibility tests still need to be further clarified. Here, we review clinical practice and basic studies that describe each AHG reagent, summarize the advantages and disadvantages of using different AHG reagents in the presence of cold agglutinins or complement-fixing antibodies, explore the potential mechanisms by which the complement system influences detection with AHG reagents and address the question of how to optimally select AHG reagents for clinically significant antibody detection.

Evaluation of modified IAT with twoself-made low ionic-strength solutions / 中国输血杂志

【Objective】 To explore the clinical applications of low ionic strength salt solution polyethylene glycol (LISS-PEG) and low ionic strength salt solution bovine serum albumin (LISS-BSA) in the indirect antiglobulin test (IAT). 【Methods】 The common standard red blood cell(RBC) IgG irregular antibodies (anti-D, anti-M, anti-N, anti-S, anti-s, anti-Jka, anti-Jkb, anti-Fya, anti-Fyb, anti-Dia, anti-K) were reacted with RBCs with corresponding antigens in IAT with LISS-PEG and LISS-BSA modification for 5-minute and 10-minute incubations, and then compared the results with conventional IAT. One hundred of blood samples from patients presenting irregular antibodies of erythrocyte IgG were selected to observe the effect of these two self-made modification. The agglutination intensity was recorded by AABB scoring method. 【Results】 No difference was noticed in IAT intensity reaction between LISS-PEG 5-minute and 15-minute incubation (P>0.05), nor between 5-minute/15-minute LISS-BSA incubation and conventional IAT (P>0.05). However, LISS-PEG modification demonstrated a significant superiority over the conventional technique just after incubation with 5 minutes(P<0.05). 【Conclusion】 Using the self-made LISS-PEG as the enhancement medium allows not only reduced incubation time (5 minutes) but also increased intensity of the reaction, which shortens the cross-matching time for emergency blood transfusion and is worthy of popularization.

Management of transfusion needs in a case of immunizing anti-M antibody in a patient with acute myeloid leukemia.

Anti-M is a relatively common "naturally occurring" antibody. Unexpected alloantibodies in patient's serum other than ABO isoagglutinins (e.g., anti-M) may cause a discrepancy in the reverse grouping. As long as anti-M does not react at 37°C, it is clinically insignificant for transfusion. However, we found this antibody to be of "immunizing" type which was reactive at 37°C and AHG phase and showing problems in blood grouping and crossmatch. This antibody had both IgM and IgG components. When "M" antibodies active at 37°C are encountered, antigen-negative or red cells that are compatible with an indirect antiglobulin test should be provided.

Distribution of antenatal alloimmunization in the southern districts of West Bengal and its significant associated factor.

OBJECTIVES: Detection of maternal irregular antibodies against red blood cell antigen is vital in the management of hemolytic disease of fetus and newborn. There are no uniform guidelines related to antenatal antibody screening and identification in the developing Country like India. This study was aimed to identify such alloimmunization and its associations. MATERIALS AND METHODS: This prospective study was conducted on antenatal mothers at a tertiary care center. The mothers having a history of anti-D administration, blood transfusion, and autoimmune disorders were excluded from the study. Initial indirect antiglobulin test (IAT) was performed in all blood samples by conventional tube technique (CTT) to identify alloimmunization. IAT-positive samples were screened for irregular antibody by column agglutination technology (CAT). Antibody screen-positive samples were further analyzed in 11-cell panel by CAT. Antibody strength was measured by serial double dilution by CTT. The source of isoimmunization was identified by extended Rh phenotype of women, husband, and newborn. RESULTS: A total of 12 (2.3%) women out of 530 were positive for IAT and antibody screen. Antibody could be identified in 11 women, of which anti-D (5) was the most common, followed by anti-C + anti-D (4), anti-C + anti-E (1), and anti-C (1). All four cases of anti-D + anti-C were distinguished from anti-G by differential adsorption and elution. There was a significant association with alloimmunization versus increased gravid status, antepartum hemorrhage, and past history of newborns with neonatal jaundice. CONCLUSION: All pregnant women with history of antepartum haemorrhage, newborn with neonatal jundice should be screened for alloantibody for early detection and better management of HDFN.

Interference in the indirect antiglobulin test and direct antiglobulin test from rheumatoid factor.

BACKGROUND: The indirect antiglobulin test (IAT) and direct antiglobulin test (DAT) have been used as common tests for transfusion. Recently, we have found that in addition to causing false increases, rheumatoid factor (RF) can also cause false decreases in immunoassays for hepatitis B surface antigen and B-type natriuretic peptide. However, it remains unclear whether RF also interferes with the IAT and DAT. METHODS: IAT models were produced by mixing IAT-positive plasma and RF-positive plasma, then one-step and two-step IATs were adopted for detection. DAT models were produced by mixing DAT-positive red blood cells (RBCs) and RF-positive plasma, followed by detection with the DAT. The DAT models were diluted using the same RF-positive plasma, and the DAT was performed again. RESULTS: The rate of decrease of the two-step IAT (40.63%) was significantly higher than that of the one-step IAT (31.51%). Both the rate of decrease (76.67%) and increase (16.67%) of the results of the 60 DAT models were significantly higher than those of the IAT models after two-fold dilution. CONCLUSIONS: The RF can lead to both false decreases and false increases in IAT and DAT. And the interference effects are related to the RF content relative to the IgG-sensitized RBCs.

Fatal Acute Hemolytic Transfusion Reaction due to Anti-Wra.

BACKGROUND: The Wra blood group antigen is a low-frequency antigen. Antibody screening sets used in pretransfusion laboratory investigations usually do not contain a Wr(a+) cell. If subsequent cross-matching is performed without indirect antiglobulin test (IAT), Wra antibodies reacting with donor red blood cells (RBCs) will be missed. For reasonable economic and time-saving arguments the risk of missing the detection of a potential clinically relevant antibody is worldwide accepted. CASE REPORT: A 66-year-old women with a negative antibody screen rapidly deteriorated after she received two units of RBCs for symptomatic anemia after hip surgery. Diagnosis of a transfusion reaction was obscured by pre-existing and nonspecific symptoms. Laboratory investigation indicated acute hemolysis. Cross-matching in IAT was positive for the first unit, and an extended antibody identification panel showed reactivity with Wr(a+) cells. The patient did not respond to supportive therapy and died within 48 h after the start of transfusion. CONCLUSION: This dramatic case provides further evidence on the clinical relevance of Wra blood group antibodies. In addition, it underlines the clinical importance of risk awareness in the blood transfusion chain and the possible complexity in relation to patient monitoring in daily transfusion practice.

Transfusion management for patients taking an anti-CD38 monoclonal antibody.

INTRODUCTION: Pre-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. METHODS: Serum 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. RESULTS: No 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 0.2M 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. CONCLUSION: Treatment 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.

Transfusion management for patients taking an anti-CD38 monoclonal antibody

Abstract Introduction: Pre-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. Methods: Serum 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. Results: No 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. Conclusion: Treatment 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.

Daratumumab: Therapeutic asset, biological trap!

OBJECTIVES: Recently, daratumumab has been included in the therapeutic strategies for myeloma patients. This molecule is an antibody directed against CD38, strongly expressed on plasma cells. Nevertheless, as CD38 is also present on erythrocyte membrane, daratumumab interferes with immunohaematological tests, complicating the selection of compatible blood. METHODS: A total of 14 patients treated by daratumumab have been followed in our transfusion laboratory. Among them, 11 have been transfused. Dithiotreitol (DTT) has been used to inhibit the daratumumab's interference, in the pre-transfusion tests (irregular antibody screening and cross-match). RESULTS: The red blood cell treatment with DTT has been very efficacious to inhibit the daratumumab's interference in 13 patients out of 14. Some precautionary measures had to be taken into account, especially the pH and the storage conditions. An extended pheno/genotype was an additional security element in the selection of compatible blood. To simplify and to optimize the laboratory practices, a decisional flow chart has been written. CONCLUSION: DTT red blood cell treatment is very useful and efficacious in the pre-transfusion tests of patients treated with daratumumab. It allows to avoid the selection of blood bags only on the basis of an extended pheno/genotype, what is more secure and more ethical with respect to other at higher risk patients. A clear decisional flow chart allows a quality assurance gait. Collaboration with physicians is essential.

Blood Transfusion Management and Transfusion-Related Outcomes in Daratumumab-Treated Patients With Relapsed or Refractory Multiple Myeloma.

INTRODUCTION: Daratumumab, a human CD38 monoclonal antibody approved for multiple myeloma (MM) treatment, binds red blood cells (RBCs), resulting in panagglutination in compatibility tests. Published mitigation methods avoid additional testing, ensuring timely release of blood products. Blood transfusion management and transfusion-related outcomes of daratumumab-treated patients in the SIRIUS study are reported, with emphasis on 2 clinical sites. PATIENTS AND METHODS: Patients had MM treated with ≥ 3 prior lines of therapy, including a proteasome inhibitor and an immunomodulatory drug, or were refractory to a proteasome inhibitor and an immunomodulatory drug. RBC typing and alloantibody screening were performed in gel cards. Antibody identification using RBC panels was performed on patients with positive antibody screens. Hematology panels and serum chemistry were analyzed ≤ 2 days before each daratumumab infusion and the first daratumumab dose within each treatment cycle, respectively. Pre- and posttransfusion hemoglobin values were analyzed retrospectively. RESULTS: At clinical cutoff, patients received 236 transfusions; 47 (37.9%) of 124 patients received 147 packed RBC transfusions, and 17 (13.7%) received 89 platelet transfusions. No hemolysis was reported, and 1 platelet transfusion reaction was observed. At Mount Sinai, no transfusion adverse events were observed, no new unexpected RBC alloantibodies were identified, and transfusions increased hemoglobin values (median, 1.2 g/dL). At Levine Cancer Institute, 6 of 7 patients responded to transfusions, with a median hemoglobin change of 1.7 g/dL. CONCLUSION: In SIRIUS, no RBC transfusion reactions, including hemolysis, were observed. Observations from Mount Sinai and Levine Cancer Institute confirm that transfusions may be administered safely to daratumumab-treated patients.

Can serological methods help distinguish between prophylactic and alloimmune anti-D?

OBJECTIVES: Enzyme indirect antiglobulin test (EIAT) and polyethylene glycol IAT (PIAT) were evaluated for their potential use as tests to distinguish between prophylactic and alloimmune anti-D in plasma by comparing with a tube variation of the standard low ionic strength solution-IAT (LISS-IAT). BACKGROUND: Laboratories performing the screening of RhD-negative pregnant women are required to provide clinicians with guidance as to the source of detected RhD antibodies. Currently, this is derived from RhIg immunoprophylaxis history, agglutination scores and titration results, where performed. A serological test that can differentiate between prophylactic and alloimmune anti-D would be useful in the diagnosis of RhD alloimmunisation in pregnant women. MATERIALS AND METHODS: Plasma samples (n = 273) [fresh (collected from April 2014 to February 2015) and frozen (up to 2 years)] from antenatal females, preoperative males and females over child-bearing age were used in this study. Samples were identified as containing anti-D by routine column agglutination (CAT) and were tested by tube LISS-IAT, EIAT and PIAT, and a score difference was calculated. RESULTS: A total of 32% of alloimmune anti-D samples demonstrated an increase in agglutination score (+2 or +3) when tested by EIAT. A significant increase in agglutination score for alloimmune samples using EIAT compared with LISS-IAT was observed. EIAT had a sensitivity (Sn) of 59%, positive predictive value (PPV) of 100% and specificity (Sp) of 100% for alloimmune anti-D. CONCLUSION: EIAT is capable of confirming but not excluding the presence of alloimmune anti-D in samples where anti-D is detected in routine antibody screening.

Paper-based assay for red blood cell antigen typing by the indirect antiglobulin test.

A rapid and simple paper-based elution assay for red blood cell antigen typing by the indirect antiglobulin test (IAT) was established. This allows to type blood using IgG antibodies for the important blood groups in which IgM antibodies do not exist. Red blood cells incubated with IgG anti-D were washed with saline and spotted onto the paper assay pre-treated with anti-IgG. The blood spot was eluted with an elution buffer solution in a chromatography tank. Positive samples were identified by the agglutinated and fixed red blood cells on the original spotting area, while red blood cells from negative samples completely eluted away from the spot of origin. Optimum concentrations for both anti-IgG and anti-D were identified to eliminate the washing step after the incubation phase. Based on the no-washing procedure, the critical variables were investigated to establish the optimal conditions for the paper-based assay. Two hundred ten donor blood samples were tested in optimal conditions for the paper test with anti-D and anti-Kell. Positive and negative samples were clearly distinguished. This assay opens up new applications of the IAT on paper including antibody detection and blood donor-recipient crossmatching and extends its uses into non-blood typing applications with IgG antibody-based diagnostics. Graphical abstract A rapid and simple paper-based assay for red blood cell antigen typing by the indirect antiglobulin test.