Passive immune basophil activation test for the identification of allergic episodes from various adverse events elicited by haematopoietic cell transplantation: A pilot study

Background and Objectives: Haematopoietic cell transplantation (HCT) therapy tends to be associated with various complications including engraftment failure, regimen-related toxicities, and infectious diseases. In addition, HC infusion itself occasionally elicits adverse events (AEs), one of the most common AEs is an allergic reaction. As appropriate laboratory tests have not yet been established to distinguish allergy-mediated AEs from other complications, clinical responses for HCT-related AEs can only be nonspecific. In this pilot study, using passive immune basophil activation test (pi-BAT), we attempted to distinguish an HC infusion-induced allergic reaction from various HCT-related AEs. Materials and Methods: Using pi-BAT, we examined 34 patients who underwent HCT, that is, 11 with AEs and 23 without AEs as controls. Results: Two of the eleven AE cases were pi-BAT positive and, the rest of nine AE cases were negative, while all non-AE cases were negative. Both of the two positive cases showed erythema, tachycardia, plus cough. Because erythema is one of the representative symptom of allergy, those cases could be classified as allergic reaction cases or anaphylaxis cases if tachycardia and cough were concomitant symptoms of erythema. Among the nine AEs with pi-BAT negative result, four cases showed urticaria, four showed vomiting plus diarrhoea, and one showed cough. Urticaria case was strongly suspected of allergy, however, the AE cases were pi-BAT negative. Conclusion: The pi-BAT may be useful as an auxiliary diagnostic tool to confirm the possible involvement of HC infusion in HCT-related AEs and identify an immunologic mechanism for HCT-related hypersensitivity reactions.