Basophil surface expressions of CD203c and CD63 following peanut allergen ex vivo stimulation correlate with severity of allergic reactions during food challenge (HYP4P.307)

Abstract

Abstract Introduction: Food allergies are a potentially fatal disorder. However, reliable prognostic markers for predicting the severity of allergic reactions during exposures have not yet been established. Recent studies have found that basophil activation tests (BATs) may be a useful adjunct for the diagnoses of peanut and other food allergies. We hypothesize that BAT can also be a useful biomarker for predicting reaction severity during food challenges. Methods: 19 (5-25 years old) peanut-allergic participants (PA) and 5 age-matched healthy controls (AC) who enrolled in our Stanford IRB and FDA approved double blind placebo controlled food challenge (DBPCFC) protocol were given escalating oral doses (5, 20, 50, 100, 100, 100, 125 mg) of peanut and placebo (oat) on separate occasions. The DBPCFC was stopped at the first sign of an objective symptom, which was graded on the modified Bock’s scale. Prior to the DBPCFC, basophils gated via flow cytometry from 200 μl of whole blood obtained from all subjects were stimulated with peanut ex vivo for 20 minutes. Results: For PAs, 8 had grade 1, 7 had grade 2, and 4 had grade 3 reactions to peanut; the ACs had no symptom. Using linear regression, high correlation coefficients were found between Bock’s reaction grades and basophil surface expressions of CD203c (r2 =0.89) and CD63 (r2 =0.85), both p<0.001. Conclusions: Our findings suggest that suitable BATs can be a useful biomarker for predicting clinical reactivity during peanut challenges.