The Combination of Binding-Avidity of Ovomucoid-Specific IgE Antibody and Specific IgG4 Antibody Can Predict Positive Outcome of Oral Food Challenge during Stepwise Slow Oral Immunotherapy in Children with Hen’s Egg Allergy

To increase the prediction accuracy of positive oral food challenge (OFC) outcome during stepwise slow oral immunotherapy (SS-OIT) in children with hen’s egg (HE) allergy, we evaluated the predictive value of the combination of antigen-specific IgE (sIgE) with antigen binding-avidity and sIgG4 values. Sixty-three children with HE allergy undergoing SS-OIT were subjected to repeated OFC with HE. We measured the ovomucoid (OVM)-sIgE by ImmunoCAP or densely carboxylated protein (DCP) microarray, sIgG4 by DCP microarray, and the binding-avidity of OVM-sIgE defined as the level of 1/ IC50 (nM) measured by competitive binding inhibition assays. The OFC was positive in 37 (59%) patients undergoing SS-OIT. Significant differences in DCP-OVM-sIgE, CAP-OVM-sIgE, I/ IC50, DCP-OVM-sIgG4, the multiplication products of DCP-OVM-sIgE and binding-avidity of DCP-OVM-sIgE (DCP-OVM-sIgE/IC50) and DCP-OVM-sIgE/sIgG4 were compared between the negative and positive groups (p<0.01). Among them, the variable with greatest area under the receiver operating characteristic curve was DCP-OVM-sIgE/IC50 (0.84), followed by DCP-OVM-sIgE/sIgG4 (0.81). DCP-OVM-sIgE/IC50 and DCP-OVM-sIgE/sIgG4 are potentially useful markers for the prediction of positive OFC during HE-SS-OIT and may allow proper evaluation of the current allergic status in the healing process during HE-SS-OIT