Key clinical messages
A basophil activation test above the positive cut-off confirms the diagnosis of IgE-mediated allergy. Basophil reactivity and basophil sensitivity decrease over the course of allergen specific immunotherapy and EC50 (or CD-sens) seem to be particularly important in reflecting the change in clinical allergen threshold. Omalizumab decreases basophil response to allergen as a consequence of the decrease in IgE receptor density and circulating IgE.