Clinical utility of a passive immune basophil activation test for the analysis of allergic transfusion reactions

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.