Oral immunotherapy for egg white allergy Original paper

People with severe food allergies are usually told to avoid the problem food entirely, but this avoidance strategy can be difficult to maintain, especially for ubiquitous foods like eggs.

Oral immunotherapy (OIT) involves a slow and controlled increase in the consumption of the problem food to build up tolerance. For better dosage control, OIT often uses an allergen powder mixed with another food (e.g., peanut protein combined with carbs and fats).

OIT is becoming a popular strategy to manage food allergies, but adverse reactions are common, can be extremely stressful, and can cause people to stop the treatment. Is it possible to use at-home OIT to treat egg white allergy in children?

This trial had 16 children with egg allergies eat boiled egg white, starting with just 0.1–1 gram and gradually increasing the amount until they could eat 40 grams without any allergic reaction.

The outcomes were levels of egg-white-specific antibodies (IgE, sIgE, and sIgG4), details about allergic reactions, and psychological symptoms. The 16 participants were compared with 16 historical controls matched to them for age, sex, levels of egg-white-specific antibodies, allergic symptoms after eating eggs, and duration of follow-up.

The 16 children receiving OIT were able to reach the target dose (40 grams) in 5–13 months. After the buildup phase, these children’s immunological profiles were better than the historical controls’, and all but 1 child were fully desensitized to egg whites. Ten months later, 11 of the 15 desensitized children were still eating 40 grams of egg whites at least four times a week, while the other 4 were freely consuming eggs.

During the 5–13 months the protocol lasted, the median number of hospital visits was six. Mild reactions occurred in 10 of the children, and serious reactions (i.e., anaphylaxis) in 2.

While the trial was, in a way, mostly run by the parents of the participants, it was supervised by medical professionals. Allergic reactions were fairly common over the months of this trial, so keep in mind that medical supervision is essential for the safety of anyone undergoing oral immunotherapy.

The researchers didn’t state a method for their psychological evaluation, which raises doubts about their claim that “no patients exhibited psychological problems”.

Allergen immunotherapy aims to desensitize a person to a given allergen, which is to say, to raise the person’s reaction threshold to this allergen. The ideal is to reach sustained unresponsiveness — a lack of adverse reactions to an allergen after immunotherapy has been discontinued for some time.

A 2017 meta-analysis of 31 trials looking at the effects of allergen immunotherapies (mostly OIT) on IgE-mediated food allergies reported a substantial benefit in terms of desensitization (risk ratio: 0.16) and sustained unresponsiveness (risk ratio: 0.29), though the latter finding was based on a small number of studies.^[1]

When it comes to treating IgE-mediated food allergies, there are three immunotherapy options: oral (OIT), sublingual (SLIT), and epicutaneous (EPIT).

Oral immunotherapy

For sublingual immunotherapy, the overall scheme is similar, but the doses are typically much lower and the build-up phase is typically much faster.

Of those three options, OIT has yielded the best clinical and immunological outcomes: most people get desensitized to the problem food, and some achieve sustained unresponsiveness for weeks to months. For instance, one randomized controlled trial found that, of 40 children receiving egg OIT, 55% achieved desensitization at 10 months and 75% at 22 months.^[2] Furthermore, of the 30 children who achieved desensitization, 28% exhibited sustained unresponsiveness 8 weeks later.

But if the results of OIT are impressive, so are the risks. Gastrointestinal issues affected 20% of the participants, and more importantly, serious allergic reactions were relatively frequent: a few studies with small sample sizes reported a handful of severe reactions, and one larger study in 395 children reported that 95 of the 240,351 doses caused a severe reaction requiring epinephrine administration.^[3]

SLIT and EPIT have less impressive results than OIT does, but they are safer.

SLIT involves the daily application of an allergen under the tongue. After 2–3 minutes, the allergen is swallowed. SLIT offers modest desensitization with little risk of systemic side effects. It has been shown to be inferior to OIT for the treatment of allergies to peanuts and cow’s milk.^[4][5] With regard to safety, >98% of the doses used in one relatively large trial didn’t adversely affect the body beyond the oropharynx, and no epinephrine was required to treat the symptoms.^[6]

EPIT involves the application of a small allergen patch (changed every 24 hours) to the back or upper arm. Limited evidence suggests that EPIT is very safe, with mild skin irritation as the only common adverse effect. EPIT’s desensitization effects, unfortunately, are much inferior to SLIT’s, let alone OIT’s.