Background: Use of HLA-compatible platelets (PC-HLA) is recommended for platelet transfusion refractoriness (PTR) caused by HLA antibodies. Selection of PC-HLA is based on compatibility with HLA-A and -B loci, but not with HLA-C. In this study, we analyzed the transfusion effect of HLA-C locus-incompatible PC-HLA. Methods: The normalized Mean Fluorescent Intensity (nMFI) of HLA-C antibodies and the effectiveness of transfusion of crossmatch-positive platelets due to HLA-C antibodies tested at the Japanese Red Cross Kanto Koshinetsu block blood center from 2017 to 2019 were analyzed. The transfusion effect was evaluated by calculating the Corrected Count Increment (CCI) of the PC-HLA (66 products), computer-crossmatched platelets (19 products) and random platelets (7 products) transfused to a patient with HLA antibody-positive PTR (case-01) at the University of Tokyo Hospital. Results: In the study period, positive crossmatch was confirmed in 57 cases (0.25%), among which 27 (47.4%) were due to HLA-C antibody. The Cw8 antibody accounted for 55.0% of cases. The effectiveness of crossmatch-positive PC-HLA due to HLA-C antibody was 75%. Antibodies against Cw15 and Cw10 were identified in Case-01, but 75% (6/8) of the transfused HLA-C mismatched products (75%) were effective. Conclusion: HLA-C incompatibility did not affect transfusion effectiveness in most cases.

Most blood donors suffering from vaso-vagal reaction (VVR) recover when posed with elevation of the lower legs following in the semi-sitting position. In some cases, however, recovery takes an unexpectedly long time. Here, we analyze the characteristics of donors with a long recovery time after VVR.

Patients and Methods: VVR recovery records of 50 consecutive donors with a recovery time of 1 hour or more were compared with those of 80 donors with a recovery of less than 1 hour. Gender, type of donation (whole blood or platelet/plasma), and time elapsed with elevation of the lower legs and that with semi-sitting position are compared, and unexpected symptoms and causes of infusion were listed.

Results: Recovery took longer in females with whole blood donation (p=0.017). In contrast, no gender difference was observed with platelet/plasma donation (p=0.28). Recurrence of symptoms and extended time in the semi-sitting position were associated with longer recovery time. Donors with infusion therapy showed lower blood pressure when VVR occurred (p=0.035).

Comments: Consideration of these factors may be useful in therapeutic decision-making.

Daratumumab and Isatuximab are humanized IgG monoclonal antibodies (MoAbs) which target CD38. Administration results in a positive indirect antiglobulin test because erythrocytes express CD38. However, effects on the direct antiglobulin test (DAT) are unclear. We investigated DAT in 17 patients with multiple myeloma (MM) treated with these MoAbs. Tube-DAT was negative in 15 cases before administration (Pre). Nine turned positive on Day 1 after administration, and became negative again on Days 6-8. CAT-DAT was positive in 8 and 15 cases on Pre and Day 1, respectively, and all 7 cases who turned positive on Day 1 became negative again on Days 6-8. The amount of IgG bound on erythrocytes increased on Day 1 in 16 cases, and returned to near the Pre level on Days 6-8. CD38 expression on erythrocytes decreased by ~70% and ~90% on Day 1 and Days 6-8, respectively, and it is highly likely that a severe reduction in CD38 expression lead to a loss of DAT positivity on Days 6-8. Hemoglobin level decreased by 8.7% on Day 1. Low-concentration DTT treatment showed that most of the positive DAT results on Days 6-8 were caused by non-specific IgG binding. DAT of MM patients after anti-CD38 MoAb administration should be carefully interpreted, because it is affected by a reduction in CD38 expression and non-specific IgG binding.

We report two cases of hemophilia B with severe allergy to factor IX concentrates who responded well to desensitization therapy (DT). Case 1 is a 9-month-old boy with severe hemophilia B who developed anaphylaxis on the 10th exposure day (ED) to recombinant factor IX (rFIX) after starting primary prophylaxis. Case 2 is a 55-year-old male with moderate hemophilia B. He received on-demand plasma-derived FIX (pdFIX) for bleeding symptoms and developed anaphylaxis after the 4th ED to pdFIX. DT with rFIX was performed for case 1 and 2. Results: FIX allergy symptoms disappeared in both cases after DT. No adverse events were observed during DT, including allergic symptoms. Discussion: Case 2 developed anaphylaxis despite his disease severity being moderate and risk of allergy considered low. Both patients were suspected of having low inhibitor levels before and after the onset of anaphylaxis, suggesting that attention to the onset of inhibitors may be predictive of anaphylaxis. The treatment protocol for DT remains to be optimized and requires further investigation.

A man in his 20s was diagnosed with pyoderma gangrenosum and underwent emergency debridement. He had no history of a hematological disease, transfusion, or hematopoietic stem cell transplantation. ABO blood group typing results showed mixed field agglutination with both A and B blood antigens. Due to the possible association between hematological disease and pyoderma gangrenosum, bone marrow aspiration was performed and he was diagnosed with myelodysplastic syndrome with multilineage dysplasia (MDS-MLD) with chromosome 8 trisomy.

Serological tests, flow cytometric analysis, and genetic test precluded the possibility of hereditary ABO subgroup and blood chimerism, suggesting that his blood antigen expression was decreased due to MDS-MLD.

In turn, decreased A and B antigen expression and diagnosis of pyoderma gangrenosum allowed the diagnosis of MDS-MLD before he had overt abnormal hematological values.

For patients with decreased expression of both A and B blood antigens, the possibility of hematological disease should be kept in mind.

A pregnant 27-year-old female was referred to our hospital with suspicion of atypical hemolytic uremic syndrome (aHUS) due to a history of HUS-like symptoms without diarrhea in childhood. Genetic analysis revealed C3 I1157T gene mutation in this patient. She was hospitalized at 31 weeks of gestation, and classical cesarean section was performed at 37 weeks. Although she had no symptoms related to aHUS in the puerperal period, she was admitted with hematuria 8 months after delivery. We diagnosed her as having aHUS and administered eculizumab, leading to rapid improvement in her condition. Among countries, C3 I1157T gene mutation is reported most frequent in Japan. Here, early identification of this gene mutation allowed us to successfully treat the patient without plasma therapy.