Egg Oral Immunotherapy
Egg Oral Immunotherapy
Purpose of review
Egg allergy is one of the most common food allergies of childhood and no interventional therapy is currently approved by the Food and Drug Administration. Much recent research has focused on the safety, efficacy, and mechanism of oral immunotherapy (OIT) as a disease-modifying treatment.
Recent findings Small pilot studies with varying protocol designs have shown egg OIT to be relatively well tolerated, and efficacy is suggested but not formally demonstrated. At this time, no placebo-controlled randomized trial has been published confirming desensitization and no published study has convincingly demonstrated the development of OIT-induced tolerance to egg.
Summary Egg OIT is a promising modality for providing temporary protection from reactions caused by accidental egg exposure. However, the overall strength of the evidence in favor of egg OIT is limited by small sample sizes and the lack of controls, both of which are important considerations given the spontaneous resolution expected in egg allergy. More high-quality studies are necessary before egg OIT can be recommended as a viable treatment option.
Allergy to hen's egg is very common in childhood, with an estimated cumulative prevalence of 2.6% by age 2.5 years. The prevalence of egg allergy has been shown to be significantly higher in children with atopic dermatitis, and in young children, egg sensitization is a known risk factor for later progression to allergic respiratory disease. Allergic reactions to egg may vary in severity from an atopic dermatitis trigger to mild urticaria to systemic anaphylaxis, and the latter represents an important precaution when administering certain vaccines, especially influenza. Most egg allergens are susceptible to heat and gastric digestion, and it has been hypothesized that these characteristics account for the observation that many egg-allergic children outgrow it in early life. Tolerance to extensively heated (e.g. baked) egg is common and appears to be an intermittent step in this process, supporting the idea that much of childhood egg allergy is due to IgE recognizing conformational epitopes. However, a recent study reported persistence of egg allergy into the second decade. These patients tend to be distinguished by more severe clinical reactions and a robust IgE response, especially to the linear epitopes of the major allergen ovomucoid, which is a stable glycoprotein that is resistant to heat and digestion. These data suggest that multiple egg allergy phenotypes exist, and that they may be identified by specific IgE-epitope repertoires, a distinction which may have important therapeutic implications. Although many children will spontaneously outgrow their egg allergy by early school age, clearly a significant proportion, who represent the group at highest risk of anaphylaxis, will not. Oral immunotherapy (OIT) is the most extensively studied approach toward a treatment for food allergy, and there has been significant focus on using OIT for egg allergy. However, the evidence base at this stage is not robust enough to change clinical practice from the current standard of care, a strict diet eliminating exposure to the allergen. The purpose of this article is to review recent advances made in the study of OIT for egg allergy.
Abstract and Introduction
Abstract
Purpose of review
Egg allergy is one of the most common food allergies of childhood and no interventional therapy is currently approved by the Food and Drug Administration. Much recent research has focused on the safety, efficacy, and mechanism of oral immunotherapy (OIT) as a disease-modifying treatment.
Recent findings Small pilot studies with varying protocol designs have shown egg OIT to be relatively well tolerated, and efficacy is suggested but not formally demonstrated. At this time, no placebo-controlled randomized trial has been published confirming desensitization and no published study has convincingly demonstrated the development of OIT-induced tolerance to egg.
Summary Egg OIT is a promising modality for providing temporary protection from reactions caused by accidental egg exposure. However, the overall strength of the evidence in favor of egg OIT is limited by small sample sizes and the lack of controls, both of which are important considerations given the spontaneous resolution expected in egg allergy. More high-quality studies are necessary before egg OIT can be recommended as a viable treatment option.
Introduction
Allergy to hen's egg is very common in childhood, with an estimated cumulative prevalence of 2.6% by age 2.5 years. The prevalence of egg allergy has been shown to be significantly higher in children with atopic dermatitis, and in young children, egg sensitization is a known risk factor for later progression to allergic respiratory disease. Allergic reactions to egg may vary in severity from an atopic dermatitis trigger to mild urticaria to systemic anaphylaxis, and the latter represents an important precaution when administering certain vaccines, especially influenza. Most egg allergens are susceptible to heat and gastric digestion, and it has been hypothesized that these characteristics account for the observation that many egg-allergic children outgrow it in early life. Tolerance to extensively heated (e.g. baked) egg is common and appears to be an intermittent step in this process, supporting the idea that much of childhood egg allergy is due to IgE recognizing conformational epitopes. However, a recent study reported persistence of egg allergy into the second decade. These patients tend to be distinguished by more severe clinical reactions and a robust IgE response, especially to the linear epitopes of the major allergen ovomucoid, which is a stable glycoprotein that is resistant to heat and digestion. These data suggest that multiple egg allergy phenotypes exist, and that they may be identified by specific IgE-epitope repertoires, a distinction which may have important therapeutic implications. Although many children will spontaneously outgrow their egg allergy by early school age, clearly a significant proportion, who represent the group at highest risk of anaphylaxis, will not. Oral immunotherapy (OIT) is the most extensively studied approach toward a treatment for food allergy, and there has been significant focus on using OIT for egg allergy. However, the evidence base at this stage is not robust enough to change clinical practice from the current standard of care, a strict diet eliminating exposure to the allergen. The purpose of this article is to review recent advances made in the study of OIT for egg allergy.
