Hideaki Matsuura

Abstract Background Ethylenediamine tetraacetate/glycine acid (EGA) and chloroquine diphosphate (CDP) are used in transfusion testing to dissociate IgG antibodies from red blood cells (RBCs). However, the ability of these reagents to dissociate IgM antibodies sensitized to RBCs has not been comprehensively elucidated. We investigated whether EGA and CDP could dissociate cold‐reactive antibodies from RBCs and their effect on RBCs after dissociation treatment. Study Design and Methods Cold‐reactive antibody‐sensitized RBC samples were prepared by mixing group A RBCs and group B plasma and treated with EGA, CDP, and dithiothreitol (DTT). Before and after the dissociation treatment, changes in the agglutination of these RBCs were assessed using the test tube method. Flow cytometric analysis was used to confirm the nature of antibodies bound to RBCs. Additionally, RBC morphology was evaluated using scanning electron microscopy. This study utilized off‐label use of EGA and CDP. Results Flow cytometric analysis showed that antibodies sensitized to RBCs were mainly IgM antibodies. After antibody dissociation, agglutination disappeared in the EGA‐treated samples to the same degree as in the DTT‐treated samples. However, IgM antibodies remained in the CDP‐treated samples. Regarding RBC morphology, RBC surface appeared coarser in both EGA‐ and CDP‐treated samples, and RBC area was significantly smaller in the CDP‐treated samples than in the EGA‐treated samples. Discussion EGA could dissociate cold‐reactive antibodies, whereas CDP had a higher residual antibody content. This difference in dissociation ability appears to correlate with the antibody pH of the dissociation reagent. EGA treatment may be useful in cases of sensitization by high‐titer cold‐reactive antibodies.

BACKGROUND: Donor-specific antibodies (DSAs) targeting human leukocyte antigens (HLAs) substantially reduce the longevity of transplanted organs. Desensitization of DSA-positive renal transplant recipients is achieved through intravenous administration of immunoglobulin (IVIg). However, the presence and detectability of anti-HLA antibodies in IVIg preparations following administration are not fully understood. We aimed to assess whether immunoglobulin preparations contain anti-HLA antibodies that can be detected as passive antibodies when administered into the body. METHODS: We evaluated 3 immunoglobulin preparations from different pharmaceutical companies, using anti-HLA class I and II antibody specificity tests and immunocomplex capture fluorescence analysis (ICFA). RESULTS: Direct testing for anti-HLA antibodies resulted in high background errors, particularly for Venoglobulin. Diluting Venoglobulin to physiological concentrations revealed the presence of anti-HLA class I antibodies; however, no common alleles were found between the specificity identification test and ICFA.For Glovenin and Venilon, anti-HLA class I and II antibodies were detected; however, variability was observed across different test reagent lots. Moreover, dilution of the globulin formulation revealed a prozone phenomenon. CONCLUSION: The administration of IVIg complicates the accurate detection of anti-HLA antibodies, underscoring the need for careful interpretation of test results post-IVIg administration.

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.

Severe coronavirus infection (COVID-19) requires treatment with extracorporeal membrane oxygenation (ECMO). COVID-19 patients have high transfusion requirements, but there are few reports on how to manage and administer them. From 2019 to 2021, 37 patients with COVID-19 and ischemic heart disease (IHD) were enrolled. We obtained information about the patients’ background features, blood product requirements, duration of ECMO, laboratory data, and outcomes. During ECMO, transfusion was administered in both groups at the time of laboratory data reduction and ECMO weaning. IHD patients were administered each blood product in the early phase of ECMO. In contrast, COVID-19 patients were administered blood products every day during ECMO and used significantly more FFP than IHD patients. Laboratory data are generally used as a guideline for transfusion therapy, but transfusions are also administered during weaning from ECMO, it is necessary to pay attention to the status of the treatment. We need to monitor laboratory data and treatment status to manage blood products and to quickly respond to transfusion requests.