Interview conducted by April Cashin-Garbutt, BA Hons (Cantab) on 19th July 2012
Why do children get egg allergies?
The tendency to get allergies is a fairly general one, which is mostly inherited – it tends to run in families. There are several foods that are most common for children to become allergic to: milk, egg and peanuts in most countries are the most common food allergies.
There are certain things about the proteins in these foods which stimulate the immune system to develop an allergy. But, the tendency to do that is going to be much more in one child than in another. This is mostly based on their genetic makeup.
How many children do egg allergies affect?
In young children, it is between 1-2% of all young children. It is typically outgrown in later childhood years. It becomes much less common in the older children.
In the first three years of life, it is the second most common food allergy, second only to milk. By school age, aged 5 or 6, more than half have outgrown the allergy, and by the time children are 10 or 11, 80-90% have outgrown it. There are 10-20% who will keep the allergy for life.
What is the current standard treatment for egg allergies?
The standard treatment is the same as for all food allergies, which is to strictly avoid the food to prevent reactions. Essentially the strategy is just to avoid the food and be ready to react if there is a reaction.
Your research showed that giving egg to children with egg allergies can help to ease or eliminate their allergy. This seems counterintuitive. How did your research originate?
This idea is a very old one, and it is the same idea that underlies the use of allergy shots – which are very effective for people who have environmental allergies and bee sting allergies.
When allergy shots were tried for food allergies, however, it turned out the risk of bad reaction was far too high to make them useful or feasible.
This approach is really similar, as it is gradually exposing the person to what they are allergic too, hopefully to teach the body to tolerate that substance over time. In this case we exposed mice to the allergen via an oral route rather than injections (as is the case in allergy shots).
Did your research show a benefit to all children with egg allergies, or were some allergies too severe to be helped by this treatment?
This is a small study so we can’t make any huge conclusions. But what we found was that of those children on the real egg treatment – as some were give placebos – there were four who could not tolerate the treatment. This was consistent with other studies in milk and peanut, where about 10% of children are unable to tolerate the treatment.
Of those that could tolerate the treatment, all of them achieved a significant increase in their ability to tolerate egg.
One of our other questions was whether you need to keep being exposed to egg to stay protected. We took the children off of the egg for 4-6 weeks at the end of the treatment period and found that some of the children did become more allergic to egg after they were not having daily egg exposure.
About 25% of the children tested could eat full servings of egg and it didn’t appear to matter whether they kept it in their diet or not. About 75% did do well during the treatment, but did become more allergic once they had stopped being exposed to the egg treatment.
They could all still eat egg-containing foods so they were much more protected than they were at the beginning of the study, but they had limitations as to what they could take and they had to have precautions of keeping the egg in their diet on a regular basis. There was the risk that they would get more allergic if they did not keep up their regular exposure.
At what age were the children given the oral immunotherapy and did this affect the benefit that they gained from the therapy?
This study was done in 5 to 11 year olds, so it is a relatively narrow age range, so we can’t really comment on whether one age did better than another.
In other studies we have seen benefits even in adults and probably even in younger children. We are not certain if this is going to be most effective for a specific age and right now we think it is more likely to work equally well for people of any age.
How many times did the children have to be given the therapy before they saw a benefit?
They started with an extremely small amount of egg. The first dose that they were given was literally 1/80,000th of an egg. That dose was then gradually increased over 6 and 10 months. The goal we had was to get them up to 2000mg of egg protein, which is equal to a ¼ of a large egg. They then stayed on that dosage for one year and that is when the outcome of the study was reported.
What do you think is the mechanism behind the benefit of this oral immunotherapy?
We think that the mechanism is that a certain part of the immune system is really designed to develop tolerance. One thing we wonder is why do 1-2% of children get allergies when the other 98% don’t.
There are things in your immune system that are supposed to promote the development of tolerance. We think that having this exposure builds up to that part of the immune system, called T-regulatory cells, in a way that it starts to shut down the body’s reactivity to the egg protein.
Do you think this therapy method could work for other allergies?
So far it has been studied for milk and peanuts. There have been a few smaller studies for other foods like fish and tree nuts. The results all look very similar, so we are encouraged that this kind of treatment could be applied to most food allergies over time.
How do you think the future of treating children with egg allergies will progress?
The kind of information that we get from this study, which we still view as a very small study, gave a strong signal that something is really happening, as at least some of the children were cured of the allergy. This gives us the information to develop larger studies that would hopefully, in the next 5-10 years, establish this as a treatment for the typical patient out in the community.
Do you have any plans for further research in this area?
We currently have 8 other studies on-going for different foods. We have several new studies starting later this year including a new one on egg, one on peanut and one on wheat. So it is an area of very active research. There is a lot of excitement over doing something, which only 10 years ago we didn’t know would be possible.
Where can readers find more information?
These studies are long studies - our recently reported study took four years before we could publish it. So there is a delay between starting the study and getting the information out there. There are a few websites you look at for more information.
One website you can visit is the Food Allergy Initiative: http://www.faiusa.org/
There is also the Food Allergy and Anaphylaxis Network: http://www.foodallergy.org/
About Dr Robert Wood
Robert A. Wood, MD is Professor of Pediatrics and Chief of Pediatric Allergy and Immunology at the Johns Hopkins University School of Medicine, and Professor of International Health at the Johns Hopkins Bloomberg School of Public Health. After receiving his medical degree from the University of Rochester School of Medicine, he completed his residency in pediatrics at the Johns Hopkins University, where he also completed an allergy and immunology fellowship.
Dr. Wood is recognized as an expert in both food allergy and childhood asthma and has published over 150 manuscripts in scientific journals, including the New England Journal of Medicine, JAMA, Pediatrics, and the Journal of Allergy and Clinical Immunology, as well as three books and over 20 book chapters. He has served on the American Board of Allergy and Immunology and is currently on the Board of Directors of the American Board of Pediatrics and the American Academy of Allergy Asthma and Immunology.