Basophil activation test reduces oral food challenges to nuts and sesame.

Santos, Alexandra F; Bergmann, Marcel; Brough, Helen A; Couto-Francisco, Natália; Kwok, Matthew; Panetta, Valentina; Haddad, Diab; Lack, Gideon; Eigenmann, Philippe; Caubet, Jean-Christoph

BACKGROUND Nut allergic patients are often IgE sensitized to other nuts/seeds and need multiple oral food challenges (OFC) before the safe nuts can be introduced in the diet. However, OFC are time-consuming and risky procedures. OBJECTIVE to assess the utility of the basophil activation test (BAT) to predict the allergic status and reduce the need for OFC in children with one or more nut or seed allergies. METHODS Participants in the Pronuts study recruited at the Geneva and the London centers were tested on the BAT to hazelnut, cashew nut, sesame, almond and peanut, Ara h 1, Ara h 2, Ara h 6, using FlowCAST, a commercially available BAT kit, and flow cytometry. RESULTS The BAT to hazelnut, cashew nut, sesame, almond and peanut discriminated between allergic and non-allergic children, to the respective nut or seed. The optimal allergen concentration and their optimal, positive and negative cut-offs were identified for BAT and the other tests, for each nut and seed. Using BAT as a second step in the diagnostic process, following equivocal skin prick test and IgE to extracts and components, reduced the number of total OFCs by 5-15% and of positive OFC by 33-75% (except for hazelnut) with 0% false-negatives and a diagnostic accuracy of 96-100%. CONCLUSION The BAT proved to be a useful diagnostic tool, used in a stepwise approach, to predict the allergic status and reduce the number of OFC in the Pronuts study patients with at least one nut allergy willing to consume selected nuts.