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Background and Objectives In previous studies, we demonstrated that the basophil-activating effects of supernatants found in residual-transfused platelet concentrates ( PC- SNs) on whole blood basophils in cases of allergic transfusion reactions ( ATRs) could be assessed by the basophil activation test ( BAT) in terms of allergen/IgE dependency. However, in these studies, the basophils were derived from third-party healthy volunteers. In this study, we performed BAT using patients' own blood basophils to analyse ATRs. Materials and Methods The BAT was performed in two cases of severe ATRs using residual PC- SNs and the patients' own basophils in the presence and absence of dasatinib, an inhibitor of IgE-mediated basophil activation. Results In both cases, PC- SNs exhibited basophil-activating activity against the patients' basophils, but not against basophils from third-party healthy volunteers. In addition, basophil activation was inhibited in the presence of dasatinib, indicating that the basophils were activated in an allergen/IgE-dependent manner. Of note, the basophils in Case 2, but not in Case 1, were activated by PC- SNs from some unrelated non-haemolytic transfusion reaction cases. Conclusion This pilot study indicates that the BAT may be useful in clarifying the causal relationship between ATRs and transfused blood as well as in elucidating the mechanisms behind ATRs considering the allergen/IgE-dependent pathway. [ABSTRACT FROM AUTHOR]

Background and Objectives The Fcgamma receptor IIIb (Fc γ RIIIb) carries the human neutrophil antigen ( HNA)-1 system. The three FCGR3B alleles encode four antigens: one allele encodes HNA-1a, and two alleles encode two antigens each, HNA-1b and HNA-1d and HNA-1b and HNA-1c, respectively. Several other non-synonymous substitutions have also been reported. Little is known about the properties of HNA-1d antibodies because HNA-1d was recently discovered, and HNA-1d antibodies have been reported only in a couple of cases. These findings raise the possibility that the polymorphisms in the HNA-1 system and spectrum of the specificity of resulting antibodies are more complex than previously thought. We address this possibility in this work. Materials and Methods Several HNA-1 antibodies, which had been classified as HNA-1a or HNA-1b before HNA-1d was discovered, were re-evaluated for their reactivity to different recombinant variants of Fc γ RIIIb. Results The HNA-1a antibody, but not the reference HNA-1a antibody, cross-reacted to HNA-1d. Further, nucleotide replacement in FCGR3B alleles *02 at 193G→A ( AA position 54 E→K) resulted in the disappearance of HNA-1d, but not HNA-1b, antigenicity. Conclusion The HNA-1 system may be more complex than previously understood. [ABSTRACT FROM AUTHOR]

Background and Objectives CD36 antibody ( Ab) causes several disorders: neonatal alloimmune thrombocytopenia, platelet transfusion refractoriness and non-haemolytic transfusion reactions. However, there is no gold-standard test for CD36 Ab. Materials and Methods We developed a transfectant panel cell line-based Mo Ab-independent antigen capture assay system for detection of CD36 Ab and compared it with the monoclonal antibody-specific immobilization of platelet antigens ( MAIPA) system in terms of sensitivity and specificity. Results Our new system was characterized by (1) gene-transfected cell lines, but not panel platelets; (2) not being hampered by HLA Abs; and (3) no need to use CD36 Mo Abs to ensure the antigen specificity of this detection system. In addition, it showed a much better receiver operating characteristic curve than the MAIPA system. Conclusions The present results indicate that our new system permits highly sensitive and specific detection of CD36 Ab. [ABSTRACT FROM AUTHOR]

A panel of platelets expressing various human platelet antigens (HPAs) for a platelet antibody screening assay is difficult to prepare because some antigens are rarely expressed. Therefore, an alternative method without using platelets would be helpful in detecting HPA antibodies. This study describes the establishment of cell lines that stably express specific HPAs and their application for detecting specific antibodies. Wild-type β3, HPA-1b, -6b, -7b and -7 variant cDNA as well as wild-type αIIb and HPA-3b cDNA were individually co-transduced with wild-type αIIb and β3 cDNA in the K562 cell line. We performed an immunobead monoclonal antibody immobilisation of platelet antigens (MAIPA) assay to evaluate this cell line panel for antibody detection using identified sera containing HPA antibodies, whose specificities had been determined by the mixed passive haemagglutination test. Of the 12 sera containing HPA-1a ( n = 2), HPA-3a ( n = 6), HPA-6b ( n = 3) or HPA-7 variant ( n = 1) antibodies, all antibodies were detected and determined by our new method, except for two HPA-3a antibodies. One of the two antibodies was also negative for conventional platelet MAIPA, suggesting that the cell line panel might be used as an alternative source of platelet antigens in the MAIPA assay. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented commenting on the examination of allergic transfusion reactions by the basophil activation test.

Although flow cytometric (FCM) analysis is one of the most widely used approaches to screen the presence of leucocyte antibodies, it has several drawbacks. First, neutrophils and, especially, monocytes exhibit high background reactivity. Second, to determine antibody specificity, it is often necessary to examine not only neutrophils and monocytes but also other lineage cells including T cells, B cells and platelets. Therefore, we attempted to establish an FCM analysis system in which four lineages of leucocytes and platelets are simultaneously tested with low background. FCM analysis was performed using ethylene diamine tetraacetic acid-anticoagulated whole blood as cell sample without any cell preparation. Discrimination of five cell lineages was carried out based on the differences in forward vs. side scatter distribution and in the expression of CD4, CD20 and CD14. When anti-HNA (human neutrophil antigen) 1b antiserum was applied to HNA 1b-positive blood samples, only neutrophils were unambiguously positive. When anti-Naka (anti-CD36) antiserum was applied, only platelets and monocytes were positive. The background reactivity of neutrophils and monocytes was low enough. When anti-human leucocyte antigen (HLA) class II antiserum was tested, only B-lymphocytes and monocytes were positive. When anti-HLA class I antiserum was tested, all the five-lineage cells were positive. [ABSTRACT FROM AUTHOR]