IgE Antibody Function and Mast Cell Activation to Egg in Children Undergoing Baked and Loosely Cooked Egg Challenges

An accurate diagnosis of egg allergy is extremely important. Understanding egg-specific antibody function can inform future therapeutic strategies. We aimed to assess the diagnostic performance of the mast cell activation test (MAT) to egg and how IgE characteristics and IgG4 modulate mast cell response to egg allergens.

BAT2 egg study participants with complete clinical outcomes and samples available for MAT were grouped based on oral food challenges (OFC) to baked egg (BE) and loosely cooked egg (LCE). Raw egg allergy was not assessed. IgE levels, specific activity, diversity, avidity for egg allergens and ratios of egg-specific IgG4/IgE were compared between baked egg allergic (BEA) and baked egg tolerant (BET) children and related to MAT and basophil activation test (BAT) to egg.

BAT2 egg study participants studied (n = 133) included 58 BEA and 75 BET (16 LCE allergic and 59 LCE tolerant). MAT to egg showed an area under the ROC curve (95% CI) of 0.749 (0.663; 0.835) for BEA and 0.704 (0.616; 0.793) for LCE allergy. Sensitivity/specificity of MAT's optimal cut-off was 52%/89% for BE allergy and 70%/66% for LCE allergy. Diagnostic accuracy of MAT was 68% for both forms of egg allergy, which was lower than that of other tests. MAT was dependent on the presence of allergen-sIgE and had superior diagnostic accuracy to sIgE only when levels sIgE ≥ 1 KU/L. BAT and MAT results were moderately correlated (Rs = 0.431, p < 0.001). IgE levels, specific activity and avidity for egg allergens were directly correlated, and egg-specific IgG4/IgE ratios were inversely correlated with MAT to egg.

MAT distinguishes BEA from BET children and is a suitable tool to test IgE function and the interference of IgG4 in mast cell response to egg allergens.