Flow cytometry-based basophil and mast cell activation tests in allergology: state-of-the-art.

The major challenge in allergy diagnosis is the development of accessible and reliable diagnostics that can predict the clinical outcome upon the exposure to culprit allergen(s) or cross-reactive molecules and the identification of safer alternatives compared to current state-of-the-art methods. There is accumulating evidence that flow-based analyses for the quantification of activated basophils and mast cells upon in vitro challenge (Basophil and Mast Cell Activation Test, or BAT and MAT) could meet the diagnostic requirements for IgE-dependent allergies, drug hypersensitivities and subsets of autoimmune urticaria. Furthermore, BAT and MAT found application in research and other non-diagnostic fields. However, the appropriate use of BAT and MAT requires understanding of the diversity of the source materials used and degranulation metrics to ensure correct test performance and interpretation of results. In this review, we provide the main applications and limitations of BAT and MAT hitherto performed.