Wheat allergy in children - new tools for diagnostics

Background: The detection of wheat-specific IgE in children often leads to a suspicion of wheat allergy, but little information is available on the most reliable wheat allergens for predicting clinical reactivity.

Objective: To evaluate the role of allergenic components of wheat in wheat allergy diagnostics.

Methods: One hundred and eight children (median age 1.5 years; range 0.6-17.3 years) with suspected wheat allergy underwent open or double-blinded, placebo-controlled oral wheat challenges. Responsiveness to different allergenic components of wheat was studied by skin prick tests and by determination of serum IgE antibodies using a semi-quantitative microarray assay.

Results: Thirty (28%) children reacted with immediate symptoms, and 27 (25%) with delayed symptoms to ingested wheat, whereas 51 (47%) children exhibited no reactions in oral wheat challenges. Positive IgE responses to any of the 12 allergenic components of wheat was seen in 93%, 41%, and 43% of those with immediate, delayed or no reactions to ingested wheat, respectively (P < 0.001 to P < 0.05 in every comparisons between those with immediate reactions and those with no reactions). Positive IgE responses to ≥5 different allergenic components improved significantly the diagnostic accuracy (with a positive likelihood ratio (LR+) of 5.10). Alpha-amylase inhibitors (AAI), in particular dimeric AAI 0.19 (LR+ 6.12), alpha-, beta-, and gamma-gliadins (LR+ from 3.57 to 4.53), and high-molecular-weight (HMW) glutenin subunits (LR+ 4.37) were the single allergenic components of wheat differentiating most effectively those with immediate symptoms from those who did not exhibit any reactions.

Conclusions and clinical relevance: Wheat allergy diagnostics is difficult, even using sophisticated component methods. Our results confirm earlier findings about gliadins and identify the dimeric AAI 0.19, as a relevant allergen in clinically reactive patients when compared to non-reactive subjects. The accuracy of wheat allergy diagnosis may be improved by measuring IgE responses to several components of wheat.