Evaluation of an in vitro Mast Cell Degranulation Test in the Context of Food Allergy to Wheat

Abstract

Background: Antigenic profiles obtained by ELISA with IgE from patients with wheat food allergy (WFA) established that major allergens are albumins/globulins (AG) for children suffering from atopic eczema/dermatitis syndrome (AEDS), ω5-gliadins for adults suffering from wheat-dependent exercise-induced anaphylaxis (WDEIA), anaphylaxis or urticaria and low-molecular-weight (LMW) glutenin subunits for patients with anaphylaxis. We aimed to characterize a new mast cell transfectant for its ability to degranulate with wheat proteins and patient sera and compare these results to those obtained by ELISA. Methods: Thirty sera from patients with WFA were tested: 14 with AEDS (group 1) and 16 with WDEIA, anaphylaxis or urticaria (group 2). An IgE Fc receptor (FcΕRI) humanized rat RBL-2H3 line was established by transfection with cDNAs encoding α-, β- and γ-subunits for the human IgE receptor. Results: A humanized RBL clone was selected for its capacity to express mRNA α-, β- and γ-subunits of FcΕRI, to bind allergen-specific human IgE and to degranulate. In group 1, sera induced enhanced degranulation with AG extract, but rarely reacted with gliadins and glutenins. In group 2, half of the sera showed degranulation with LMW glutenins whereas the AG fraction and lipid transfer proteins were rarely positive. ω5-Gliadins did not appear as a major allergen in degranulation assays, although functional allergen-specific IgE was measurable in appreciable amounts. Conclusion: Our data demonstrate that in wheat food allergen evaluation, correlation exists between mast cell degranulation and IgE measurements, depending on the type of allergen. Therefore, the biological activity of some allergen types may also be affected by other parameters.