Egg oral immunotherapy desensitizes most children after prolonged treatment
Published Online: May 2021
Egg allergy is the second most common food allergy in children. Egg allergy may persist until adulthood, which increases the risk of anaphylaxis and reduces quality of life. Oral immunotherapy (OIT) is an experimental treatment for food allergy, where gradually increasing doses of food allergens are administered orally. OIT can desensitize more than 80% of children with egg allergy and elicit long-term tolerance in 50% after 4 years of treatment.
In a recent article in The Journal of Allergy and Clinical Immunology: In Practice, Palosuo et al. describe the results of a randomized, open-label trial of oral immunotherapy (OIT) for hen’s egg allergy. The study included 50 children and adolescents, aged 6-17 years, referred to the Department of Allergology, Helsinki University Central Hospital, Finland for evaluation of egg allergy. The inclusion criteria included a clinical history of egg allergy, sensitization to egg white, and a moderate to severe reaction in a double-blind, placebo-controlled oral food challenge to heated egg white. The children were randomized to start OIT with raw egg white powder or continue egg avoidance for 6 months after which the avoidance group started OIT. The target maintenance dose (1 g of egg white protein) is equivalent to approximately one-third of an egg white. Blood samples for measurement of IgE, IgA, and IgG4 antibodies specific for egg white and the egg allergen molecules Gal d 1, 2, 3, and 4 were drawn at baseline and after 3 and 8 months of OIT.
Desensitization to egg was assessed after 8 and 18 months of OIT. Children able to consume the target maintenance dose (1g egg white protein) without symptoms were considered desensitized, and those able to consume any dose below the target dose were considered partially desensitized. The partially desensitized children continued updosing with raw egg powder, and in the case of continuous symptoms, they switched to heated egg. After reaching the target dose, the children consumed a total amount of one-third of an egg daily. After 3 months, an oral egg challenge with one-half of a boiled egg white was performed. If passed, the patients were allowed to consume up to one-half of an egg in the heated form, but the amount of raw egg was not increased. Daily consumption was continued and they were advised to add heated egg products (e.g., meatballs, pasta, bread, pancakes, pastries) into the diet.
The authors reported that after 8 months of OIT, 44% of the children were desensitized, 46% partially desensitized and 10% discontinued. In one patient, egg allergy had resolved during the 6 months elimination diet. The authors showed that high egg white-specific IgE levels and sensitization to all four egg allergen molecules Gal d 1-4 were related with discontinuation and impaired response at 8 months. However, after 18 months of OIT, 88% of the children were regularly consuming egg and 72% were desensitized to the target dose. Most of the children were able to incorporate egg products into their daily diet and more than half were able to liberate dietary restrictions of egg products. The authors conclude that OIT with raw egg enables the liberal inclusion of egg products into the daily diet in most children with persistent allergy to heated egg. Many patients with high baseline IgE levels and sensitization to multiple egg allergen components achieve desensitization after individually adjusted, prolonged treatment.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.