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Background: The basophil activation test (BAT), performed with patient blood samples and supernatants from transfused blood, was developed to elucidate the mechanistic relationship between transfusion and the resultant allergic transfusion reactions (ATRs). This test cannot be performed on myelosuppressed patients and neonates because of the absence of basophils. Therefore, we devised the passive immune basophil activation test (pi-BAT) using patients' plasma and residual transfused blood as sources of immunoglobulin E and allergen, respectively, and the basophils of healthy volunteers served as a source of the responder cells. The sensitivity and specificity of the pi-BAT, however, remained largely unknown., Study Design and Methods: In this study, the pi-BAT was performed on 31 patients with nonhemolytic transfusion reactions including nine non-ATR and 22 ATR (12 mild and 10 moderate-to-severe) cases to examine its sensitivity and specificity., Results: Nine of the 10 cases with moderate-to-severe ATR tested positive, whereas all the non-ATR cases negative, strongly indicating immunoglobulin E and allergens are involved in the pathogenesis underlying the blood transfusion-triggered adverse effects., Conclusion: Thus, we propose that pi-BAT can be used to detect moderate-to-severe ATRs and their underlying mechanisms., (© 2019 AABB.)

Background: In most cases of allergic transfusion reactions (ATRs), the causative agents have not been identified and the mechanisms are largely unknown, with a few exceptions. The basophil activation test (BAT) was recently introduced in the field of transfusion to investigate the causal relationships between ATRs and transfusion, as well as the mechanisms behind them., Study Design and Methods: The BAT was used to screen the residual supernatants (SNs) of 43 blood components associated with serious ATRs for those that can activate basophils of many healthy volunteers. The SNs were then fractionated by centrifugal ultrafiltration and protein G column chromatography and each separated fraction was reexamined by the BAT., Results: Of the 43 such blood components, one activated basophils from 19 of 21 healthy volunteers. In the blood component, the IgG antibody against IgE was identified as a putative causative agent., Conclusion: Blood donors who possessed the IgG antibody against IgE may be dangerous to transfusion recipients. The BAT would be useful in identifying such high-risk blood donors, when it is used to screen the blood components associated with serious ATRs for residual SNs that can activate the basophils of many healthy volunteers., (© 2018 AABB.)

Allergic transfusion reactions (ATRs) are the most common adverse reactions occurring during transfusion of blood components. Although most reactions are mild and involve cutaneous manifestations, severe ATRs including life-threatening anaphylaxis may also occur. The mechanisms of ATRs are largely unknown because they have not been well studied. One of the reasons for this may be the absence of a standard assay system for investigating these processes. Basophils and/or mast cells are key effector cells in immediate-type allergic reactions. They possess the unique ability to degranulate upon cross-linking of specific IgE bound on the membrane-bound, high-affinity IgE receptor or upon direct stimulation by exposure to allergens. Basophils are present in peripheral blood, unlike mast cells which are located in tissues. Therefore, basophils are valuable for the clinical testing of allergy. Consequently, the basophil activation test (BAT) was developed as a simple blood test for the diagnosis of allergic reactions to substances such as foods, inhalants, medicines and venom. In the last decade, the BAT has also been applied to transfusion medicine; 5 pilot studies revealed that the supernatants of the responsible blood products activated basophils in the BAT in 13 ATR cases, suggesting a causal relationship between ATRs and transfusion. In this review, we describe those cases and explore the potential utility of the BAT as a test performed in reference laboratories for the analysis of ATRs. We also describe the weaknesses, pitfalls, and unanswered issues of this assay., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: In previous studies, we demonstrated that the basophil activation test, which is performed using patient blood and the supernatants from transfused blood components, was able to elucidate not only the causative relationship between allergic transfusion reactions and the transfusion but also the mechanisms behind allergic transfusion reactions. However, for a large number of allergic transfusion reactions, patients are in a state of myelosuppression, and the basophil activation test cannot be performed for these patients because there are insufficient numbers of peripheral blood basophils., Study Design and Methods: To overcome this obstacle, we developed a passive immune basophil activation test, in which patient plasma and residually transfused blood are used as the patient's sources of immunoglobulin E and allergen, respectively, whereas healthy volunteer basophils serve as the responder cell source. The passive immune basophil activation test was performed for two patients who had severe allergic transfusion reactions, using supernatants of the residual platelet concentrates and the patients' own immunoglobulin E., Results: There were no differences in either surface immunoglobulin E or activation in response to allergens between untreated basophils and so-called quasi-basophils, in which immunoglobulin E was replaced by a third party's immunoglobulin E. In these patients, the supernatants of the residual platelet concentrates exclusively activated basophils in response to quasi-basophils onto which the patients' immunoglobulin E, but not a third party's immunoglobulin E, was bound., Conclusion: The passive immune basophil activation test may help clarify the causal relationship between allergic transfusion reactions and transfused blood, even when patients experience myelosuppression., (© 2017 AABB.)

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., (© 2017 International Society of Blood Transfusion.)