The Safety of the Oral Food Challenge Test with the Small Amount of Wheat for the High Risk Patients

T U E S D A Y 810 Is the Allergen-Specific Basophil Activation Test (BAT) Predictive of Oral Food Challenge (OFC) Outcomes? Vijaya Knight, MD, PhD; National Jewish Health, Denver, CO. RATIONALE: Although specific IgE (sIgE) is the primary laboratory test for diagnosis of food allergy, some patients with elevated sIgEmay only be sensitized. The OFC carries many risks and challenges. This study was undertaken to determine whether an allergen induced BAT is more predictive of food allergy than sIgE/SPTand a potential surrogate for OFC. METHODS: BAT was performed on heparinized blood from patients undergoing OFC. Allergens included egg, milk, peanut, soy, wheat, almond, cashew, hazelnut, Brazil nut, walnut and pistachio. Allergenspecific upregulation of the basophil-specific ectoenzyme E-NPP3 (CD203c) was measured by flow cytometry. The extent of basophil activation, (fold increase of CD203c expression over baseline), was correlated with sIgE, SPT and OFC outcomes. RESULTS: 9 children underwent testing; 1 was excluded for inadequate response to positive control (anti-IgE). 57% demonstrated basophil reactivity to peanut; 43% egg; 40% pistachio, pecan, hazelnut, Brazil nut, cashew, and almond; 33% walnut; 29% milk and soy. Children with negative SPT or sIgE were not BAT positive, indicating good correlation for negative results. Two sensitized patients with negative BAT passed OFCs. CONCLUSIONS: This preliminary data demonstrates the utility of BAT in diagnosing food allergy. In this small cohort, specificity of the BAT appears equal, if not superior to sIgE and SPT in identification of patients with food allergy. The two patients with negative BAT passing OFC suggest that BAT could be used to guide the need for OFC. Recruitment to this study is ongoing. Further studies will focus on the BAT in select patient groups (e.g.; atopic dermatitis, high IgE).