Relationship between specific IgE to egg components and natural history of egg allergy in Danish children

BACKGROUND: The majority of egg-allergic children develop tolerance over time. However, it may take numerous of consecutive egg challenges to get there as no good indices to predict tolerance exist. OBJECTIVE: To investigate whether serial measurements of specific IgE to egg white, ovomucoid, ovalbumin, conalbumin, lysozyme, and egg yolk could improve the specificity of the diagnostic workup and aid in the decision when to rechallenge egg-allergic children. METHODS: The outcome of oral food challenges with hen's egg and corresponding specific IgE levels were evaluated in children referred to The Allergy Center within an 8-year period. The egg-allergic children were rechallenged and had specific IgE levels measured once a year. RESULTS: During a median follow-up of 26 months, 287 challenges and corresponding 287 serum analyses were performed in 130 children. Of the 130 children, 99 were egg allergic and 82 of these were rechallenged. Based on the initial diagnostic challenges only, area under the curve (AUC) estimates of the ability of specific IgE titers to distinguish between egg sensitization and egg allergy were only modest (maximum 0.83) and provided no clinical meaningful decision points. Specific IgE levels at baseline did not differ between tolerant and persistent allergic children. However longitudinally, acquisition of tolerance was associated with a decrease in IgE to egg white and to ovomucoid. In all cases of an increase in IgE to ovomucoid, the rechallenge was positive. CONCLUSION: The decision when to rechallenge egg-allergic children should encounter the course of specific IgE.