Significance of ovomucoid- and ovalbumin-specific IgE/IgG(4) ratios in egg allergy.

BACKGROUND The role of specific IgG(4) antibodies in natural tolerance acquisition remains a matter of debate; the specific IgE/IgG(4) ratio might add value to the measurement of absolute amounts of IgE for assessing the ongoing status of egg reactivity. OBJECTIVE We sought to determine the significance of IgG(4) antibodies to ovalbumin (OVA) and ovomucoid (OVM) in egg-allergic children. METHODS One 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 IgG(4) to OVM and OVA, component IgE/IgG(4) ratios, and mediator release in a functional assay based on the rat basophil leukemia cell line. RESULTS Baked egg-reactive children had significantly higher OVA and OVM ratios of IgE/IgG(4) and mediator release in the rat basophil leukemia-based assay than did tolerant children (P < .05 for both). The OVA- and OVM-specific IgE/IgG(4) 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 IgG(4) to OVA and OVM were significantly greater compared with the areas under the curve for egg white-specific IgE and OVM-specific IgE. CONCLUSIONS The balance between IgE and IgG(4) to OVA and OVM has functional consequences. A model that includes the interactions between IgE and IgG(4) to OVA and OVM accurately predicts reactivity to baked egg and warrants further investigation.