Giving children and adolescents with egg allergy small but increasing daily doses of egg white powder holds the possibility of developing into a way to enable some of them to eat egg-containing foods without having allergic reactions, according to a study supported by the National Institutes of Health.
The study results will appear online in the July 19th issue of the New England Journal of Medicine.
"Children with egg allergy are at risk for severe reactions if they are accidentally exposed to egg-containing foods," said Anthony S. Fauci, M.D., director of the NIH's National Institute of Allergy and Infectious Diseases (NIAID).
Fauci continued, "Currently, the only way to prevent these reactions from occurring is for these children to avoid foods that contain eggs. While this relatively small study provides encouraging new information, it is important for the public to understand that this experimental therapy can safely be done only by properly trained physicians."
The study is one of several federally funded trials of oral immunotherapy (OIT), an approach in which a person with food allergy consumes gradually increasing amounts of the allergenic food as a way to treat the allergy.
Because OIT carries significant risk for allergic reactions, these studies are all conducted under the guidance of trained clinicians.
Symptoms of allergic reactions can range from mild (hives, redness and itchiness of the skin) to severe (swelling of the back of the throat, trouble breathing, drop in blood pressure, and faintness or dizziness).
The trial was conducted by the NIAID-supported Consortium of Food Allergy Research (CoFAR) at clinical sites in Baltimore; Chapel Hill, N.C.; Denver; Little Rock, Ark.; and New York City.
The goals of the study were to determine if daily egg OIT reduced or eliminated participants' allergic responses to egg protein and if it did, whether or not the benefit persisted after therapy was stopped for four to six weeks.
The CoFAR study enrolled 55 children and adolescents aged 5 to 18 years who had egg allergy, one of the most common food allergies seen in children.
Participants were randomly assigned either to the treatment group, which received egg OIT (40 participants), or to the control group, which did not (15 participants). Both groups were followed for 24 months.
Participants received a daily dose of egg white powder or cornstarch powder (placebo) at home. Researchers gradually increased the dose of egg or placebo powder every two weeks until the children in the egg OIT group were eating the equivalent of about one-third of an egg every day.
Participants came to the clinic to have three oral food challenges, at 10 months, 22 months and 24 months, with the maximum challenge equivalent to one egg.
They passed the challenge if they had either no symptoms or only transient symptoms not directly observable by a doctor, such as throat discomfort. Participants failed the challenge if they had a symptom that could be observed by a doctor, such as wheezing.
After 10 months, none of the participants who received placebo passed the challenge, but 55 percent of those on egg OIT did. After 22 months of egg OIT, researchers gave a second oral food challenge to all of the children in the treatment group. At this food challenge, 75 percent of those on egg OIT passed.
"At the beginning of the study, most of the participants were highly allergic to egg, but after months of daily egg OIT, we found that many of them could eat more than a whole egg without having a reaction," said A. Wesley Burks, M.D., chair of the Department of Pediatrics at the University of North Carolina, Chapel Hill, one of the study's lead authors.
"Reducing these kids' allergic response to egg also lessened parental anxiety over how their children might react if accidently exposed to egg at school or at someone else's house," added Stacie Jones, M.D., professor in the Department of Pediatrics at the University of Arkansas for Medical Sciences, Little Rock, another lead author on the study.
To determine if egg OIT had any long-term benefit on treating the children's food allergy, the participants who passed the 22-month test were completely removed from egg OIT for four to six weeks and then rechallenged at 24 months.
Eleven of the original 40 children (about 27 percent) passed this third food challenge. None of the children from the placebo group were retested because they had failed the prior food challenges.
The 11 children who passed the third test were allowed to eat egg or egg-containing foods in their normal diets as frequently or infrequently as they chose. At a one-year follow-up, they reported no symptoms.
According to the study authors, these results indicate two types of benefits. First, the majority of the study children could be safely exposed to egg while on egg OIT. Second, a small group of children - approximately one-fourth - were able to eat egg in their regular diets even after stopping OIT for four to six weeks.
"Although these results indicate that OIT may help resolve certain food allergies, this type of therapy is still in its early experimental stages and more research is needed," said Daniel Rotrosen, M.D., director of the NIAID Division of Allergy, Immunology and Transplantation, which oversees CoFAR. "We want to emphasize that food OIT and oral food challenges should not be tried at home because of the risk of severe allergic reactions."