Human basophil activation measured by CD63 expression and LTC4 release in IgE-mediated food allergy

Background: IgE-dependent basophil activation induced by an allergen elicit the release of LTC4 and the expression of the CD63 membrane marker. Objective: The aim of this study was to check if flow cytometric analysis o f basophil activation could be applied to food allergy diagnosis and if thi s method paralleled LTC4 release. Methods: Patients were selected by the clinical history, skin tests, and pr ovocation tests. Basophil activation induced by food extracts was studied i n 24 control subjects and in 27 patients having a food allergy by LTC4 rele ase test (LRT) and by flow cytometric anti-IgE+, CD63+ cell counting (BAT = basophil activation test). In case of negative anti-IgE response a passive blood donor basophil passive sensitization step was added to LRT and BAT. Leucocyte histamine release test was performed in 11 patients. Results: Basophil activation test was positive in 18/31 cases and LRT in 22 /34 cases for food-allergic patients and, respectively, in 1/33 and 1/35 ca ses for the controls. A correlation was observed between specific IgE, BAT, and LRT. Basophil activation test and LRT performed after passive sensitiz ation had an excellent sensitivity only for specific IgE levels ranging bet ween 3.5 and 35 KU/L. Conclusion: The present study shows that allergen-induced LTC4 release and anti-IgE, antiCD63 bicolor flow cytometric analysis of basophil activation may be used for food allergy diagnosis. Both tests have a good sensitivity and specificity. Basophil activation test and LRT are more efficient than h istamine release test in case of high spontaneous histamine release, freque ntly observed in case of food allergy.