The Basophil Activation Test in Allergy Diagnostics: Clinical Applications, Methodological Challenges, and Proposed Clinical Frameworks

The basophil activation test (BAT) is a modern in vitro functional assay used for the diagnosis of immunoglobulin E-mediated allergic reactions. The method is based on flow cytometric assessment of activation marker expression on peripheral blood basophils after stimulation with specific allergens. BAT has gained increasing clinical relevance in allergology, particularly in patients with anaphylaxis risk, polysensitization, drug hypersensitivity, and inconclusive skin or serological test results. This narrative review summarizes current evidence on the diagnostic performance and clinical applications of BAT in food allergy, drug hypersensitivity, Hymenoptera venom allergy, latex sensitization, and allergen immunotherapy monitoring. The review discusses the immunological mechanisms of basophil activation, the role of CD63 and CD203c, methodological aspects of the assay, sensitivity and specificity data, and advantages and limitations compared with conventional diagnostic approaches. Particular attention is given to protocol standardization, interpretation criteria, and the problem of non-responder patients. Current evidence indicates that BAT demonstrates high specificity and provides functional assessment of clinically relevant allergic reactions. In addition, this review proposes practical clinical frameworks for integrating BAT into allergy diagnostic pathways and for managing inconclusive or non-responder BAT results. Further standardization, multiplex formats, and automated analytical approaches may expand its role in personalized allergy diagnostics.