松浦 秀哲

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.

体外式膜型人工肺（extracorporeal membrane oxygenation; ECMO）を使用する重症新型コロナウイルス感染症（COVID-19）症例は血液製剤を要するが，その使用状況についての報告は少ない。2019年11月から2021年8月までに当施設でECMO治療を受けた重症COVID-19患者19名の患者背景，血液製剤の使用量，ECMO稼働時間，臨床検査値，転帰を調査し，解析を行った。同時期にECMOを稼働した虚血性心疾患（IHD）患者18名を対照とした。ECMO稼働中，両群ともに臨床検査値の低下時とECMO離脱に際して輸血が行われていた。IHD症例ではECMO導入早期に各血液製剤が使用されていた。一方で，COVID-19症例では血液製剤が連日使用されており，特に新鮮凍結血漿（fresh frozen plasma; FFP）使用量がIHD症例と比較して有意に多かった。輸血療法の目安として臨床検査値が一般的であるが，ECMO稼働症例では両群ともにECMO離脱時にも輸血が実施されており，治療の進捗状況に留意する必要がある。輸血管理部門としては臨床検査値，治療状況を把握し輸血要請に迅速に対応できる製剤管理を行う必要がある。