RESUMO
BACKGROUND: Despite several reports on red blood cell (RBC) alloimmunization, the actual prevalence and factors contributing to RBC alloimmunization in transfused patients remain poorly investigated. We examined the association between clinical factors and the development and evanescence of RBC antibodies after transfusion. STUDY DESIGN AND METHODS: Each participating institution performed antibody screens before and after RBC transfusion. A survey including patient characteristics, results of antibody screen and identification, antibody screen methods, total amount of RBC transfused, and adverse reactions, was conducted. RESULTS: Between October 2018 and March 2023, 1194 patients were registered at five institutions. Overall, 958 patients underwent at least one follow-up RBC antibody screen after transfusion, revealing new antibody development in 44 (4.6%). Anti-E was identified in 25 patients, anti-Jka in 5, and anti-c in 4. The number of RBC units transfused was significantly associated with antibody development after transfusion (p < .001). Among 55 patients in whom antibodies were identified after transfusion, including historical antibodies, antibodies evanesced in 18 (33%); anti-E in 7, anti-Jka in 4, and anti-Lea in 2. Evanescent antibodies were identified more frequently by saline and/or enzyme methods than persistent antibodies (p = .012). DISCUSSION: The number of RBC units transfused can impact antibody development, and antibodies identified only by saline and/or enzyme methods, deemed clinically insignificant, are likely to have a high evanescence rate. Antibody screen should be carefully performed, especially in those receiving a large number of RBC units. Confirming previous antibody screen results should be performed to prevent omitting evanesced antibodies regardless of clinical relevance.
RESUMO
BACKGROUND AND OBJECTIVES: Anti-CD38 monoclonal antibodies, including daratumumab and isatuximab, often interfere with pretransfusion testing. Dithiothreitol (DTT) treatment of red blood cells (RBCs) negates this interference. However, the optimum DTT concentration and treatment time have not been well defined. Here, we quantified CD38 on RBCs before and after DTT treatment using a flow cytometric antibody binding assay (FABA) to specify the optimum conditions for CD38 inactivation. MATERIALS AND METHODS: For FABA, untreated or DTT-treated RBCs were incubated with fluorescein isothiocyanate-labelled anti-CD38 antibody, in the presence or absence of 100-fold or more excess of unlabelled anti-CD38 antibody, and then analysed by flow cytometry (FCM). Dissociation of CD38-positive and control histograms was determined from the D-value using the Kolmogorov-Smirnov test. The results from FABA were compared with those from conventional FCM, indirect antiglobulin test (IAT) and Western blotting. RESULTS: The results from FABA were more consistent than those from conventional FCM. The D-value was found to be reliable in the analysis of difference between CD38 before and after DTT treatment. Our data showed that 0·0075 mol/l DTT for 30 min is sufficient to inactivate CD38 on RBCs. These results were stable and consistent with the findings from IAT. CONCLUSION: Flow cytometric antibody binding assay is an objective way of evaluating the efficacy of DTT treatment for CD38 on RBCs. This approach allows the detection of a small number of cell surface antigens and will be useful for assessing the various chemical treatments to denature RBC antigens.