Principles, potential and limitations of ex vivo basophil activation by flow cytometry in allergology: a narrative review.

Abstract The major challenge of allergy diagnosis lies in the development of accessible and reliable diagnostics allowing correct prediction of the clinical outcome upon exposure to the offending allergen(s) and cross-reactive structures. Since the late nineties, evidence has accumulated that flow-assisted analysis and quantification of ex vivo activated basophils (BAT) might meet this requirement for different IgE-dependent allergies and particular forms of auto-immune urticaria. Other, so called non-diagnostic applications of the BAT involve therapeutic monitoring, follow-up of natural histories and identification of allergenic recognition sites. However, it has also become clear that appropriate use of the BAT necessitates knowledge about degranulation metrics and guidance to guarantee correct execution and interpretation of the results. Here, we review the most relevant applications and limitations of the BAT. Some personal statements and views about its perspectives are made.