Significance of ovomucoid- and ovalbumin-specific IgE/IgG4 ratios in egg allergy

BackgroundThe role of specific IgG4 antibodies in natural tolerance acquisition remains a matter of debate; the specific IgE/IgG4 ratio might add value to the measurement of absolute amounts of IgE for assessing the ongoing status of egg reactivity.ObjectiveWe sought to determine the significance of IgG4 antibodies to ovalbumin (OVA) and ovomucoid (OVM) in egg-allergic children.MethodsOne hundred seven egg-allergic children (mean age 6.9 years; range 1.6-18.6 years) were challenged to baked egg. The outcomes of the challenges were related to the level of specific IgE and IgG4 to OVM and OVA, component IgE/IgG4 ratios, and mediator release in a functional assay based on the rat basophil leukemia cell line.ResultsBaked egg–reactive children had significantly higher OVA and OVM ratios of IgE/IgG4 and mediator release in the rat basophil leukemia–based assay than did tolerant children (P < .05 for both). The OVA- and OVM-specific IgE/IgG4 ratios and mediator release were correlated. In the receiver operating characteristic analysis, the areas under the curve for a logistic regression model including specific IgE and IgG4 to OVA and OVM were significantly greater compared with the areas under the curve for egg white–specific IgE and OVM-specific IgE.ConclusionsThe balance between IgE and IgG4 to OVA and OVM has functional consequences. A model that includes the interactions between IgE and IgG4 to OVA and OVM accurately predicts reactivity to baked egg and warrants further investigation.