Elevated IL-5 and IL-13 responses to egg proteins predate the introduction of egg in solid foods in infants with eczema

BackgroundEgg allergy is a leading cause of food allergy in young infants; however, little is known about early allergen-specific T-cell responses which predate the presentation of egg allergy, and if these are altered by early egg exposure. ObjectiveTo investigate the early T-cell responses to multiple egg proteins in relation to patterns of egg exposure and subsequent IgE-mediated egg allergy. MethodsEgg-specific T-cell cytokine responses (IL-5, IL-13, IL-10, IFN and TNF) to ovomucoid (OM), ovalbumin (OVA), conalbumin (CON) and lysozyme (LYS) were measured in infants with eczema at 4months of age (n=40), before randomization to receive early egg' or a placebo as part of a randomized controlled trial (Australian New Zealand Clinical Trials Registry number 12609000415202) and at 12months of age (n=58), when IgE-mediated egg allergy was assessed by skin prick test and food challenge. ResultsIn 4-month-old infants, who had not directly ingested egg, those who subsequently developed egg allergy already had significantly higher Th2 cytokine responses to multiple egg allergens, particularly elevated IL-13 responses to OVA (P=0.004), OM (P=0.012) and LYS (P=0.003) and elevated IL-5 to the same antigens (P=0.031, 0.04 and 0.003, respectively). IL-13 responses (to OVA and LYS) and IL-5 responses (to LYS) at 4months significantly predicted egg allergy at 12months. All responses significantly declined with age in the egg-allergic infants, and this did not appear to be modified by early' introduction of egg. Conclusions & Clinical RelevanceElevated egg-specific Th2 cytokine responses were established prior to egg ingestion at 4months and were not significantly altered by introduction of egg. Th2 responses at 4months of age predicted egg allergy at 12months, suggesting that this could be used as a biomarker to select infants for early prevention and management strategies.