Infant Peanut Allergy Testing in the Post-LEAP World

Abstract

RATIONALE: Some studies suggest that the BAT more accurately predicts clinical peanut allergy than skin testing or serum IgE levels, potentially reducing the need for OFCs. However, basophils are not stable ex vivo and activation testing must take place within 3-4 hours of sample collection to achieve reliable results, thus excluding this test from most clinical settings. We tested a novel BAT prototype methodology developed by Beckman-Coulter, which can be done in the clinic and shipped to a central lab, to evaluate whether BAT results were stable over several days. METHODS: Thirty subjects with a history of peanut allergy, elevated peanut-sIgE and positive skin tests provided blood to assess the efficacy of the proposed approach. Basophils were stimulated with six increasing concentrations of peanut antigen (0.0001-10 mg/ml) and activation was measured by flow cytometry at 0, 1, 3 and 5 days post-stimulation. The dose-response curves were summarized using area under the curve (AUC). Mixed-effect models and intra-class correlation coefficients (ICC) were used to compare results across days. RESULTS: Twenty-six (87%) subjects had basophil activation (>15% CD63+) to at least one concentration of peanut extract. AUC had high agreement between day 0 and the subsequent days (ICC597%) and was not significantly different from day 0 on days 1 (p50.717) and 3 (p50.365). Day 5 activation remained positive but slightly lower than day 0(p50.004). CONCLUSIONS: With the tested methodology, cytometric analyses can be performed up to 5 days after sample collection with excellent precision, which could make BAT available for use in the standard clinical setting. J ALLERGY CLIN IMMUNOL FEBRUARY 2019 AB266 Abstracts MONDAY