WHAT IS ORAL IMMUNOTHERAPY?
Oral immunotherapy (OIT) involves the regular administration of small amounts of allergen (food) by mouth. First there is rapidly induced desensitization (the ability to tolerate an allergen while on immunotherapy), and then, in time, induce tolerance to the allergen (the long-term ability to tolerate an allergen after immunotherapy is discontinued).
Patients undergoing OIT generally ingest a mixture of protein powder in a water or some other vehicle like, apple sauce. Treatments are typically started in a controlled setting (office, hospital clinic) where gradually increasing doses of allergen are given up to a targeted dose. Following this, in standard protocols, most dosing is done at home, and increased in the office weekly.
For example with our protocols:
Peanut starting dose= 0.001mg of peanut protein; One peanut = 250mg of protein; End dose= 8 peanuts.
Egg starting dose= 0.0083mg; One egg = 4350mg; End dose one egg.
Milk starting dose = 0.1mg; 8oz of milk =8000mg; End dose 8oz of milk.
There have been scattered reports in the literature on the use of OIT for food allergy in the last 100 years. Most research on OIT has occurred in the last 25 years. A study in 1984 showed the successful treatment of allergies to cow’s milk, egg, fish, and fruits with standardized OIT protocols. I have included links to a large number of studies and their abstracts.
What is the end point?
The goal with the protocols I follow, is to reach a daily dosing schedule where not only you do not have to avoid the allergen, but can eat it on a regular basis. In some instances to patient or parent will choose to shorten the therapy and bring the protection only up to protect against accidental exposures.
The patient completing the full OIT protocol does not have to add the food back into his/her diet, but the daily maintenance dose has to be ingested to maintain the desensitization.
IS OIT EFFECTIVE?
From the literature there is overwhelming evidence that OIT will induce desensitization, meaning that the patient will be able to ingest/be exposed to the food with out any reactions.
There is little evidence on long term tolerance (basically is this a cure?). Studies are still ongoing on if therapy will induce long term tolerance (where daily doses will no longer need to be given). We know from a number of studies that after a period of time (studies have varied this length of therapy) that daily dosing can be discontinued and for a month or two the patient remained desensitized, all of these trials then put the patient back onto daily dosing schedule.
The studies encompass peanut allergies, milk, egg, and others. In general most all patients that make it maintenance are desensitized. Some protocols only went to a level to protect from incidental exposure (i.e. one peanut) more are now moving the patients to a level where they do not have to avoid the food any longer.
IS OIT SAFE?
Most patients experience mild symptoms the first day of therapy (mild hives, oral itching/burning, GI discomfort).
Severe reactions are rare occurring any where from <1%-10%(of patients) depending on the study. Most studies the rate of anaphylaxis is 5%. This reaction rate is for the total protocol not per dose.
Approximately 85% of patients finish the protocol, the 15% drop out rate is primarily due to inability to continue to keep to the schedule, and GI discomfort. There has been a few patients (1-2%) diagnosed with Eosinophilic Esophagitis and had to be discontinued (unknown if the patients had EoE prior or was induced by ingesting the allergen- I suspect there has been both).
The 15% drop out rate is less in protocols not following a rigid study schedule. This lower drop out rate is due to the ability to slow down the schedule when needed to allow symptoms to dissipate and be minimized.
What Food Allergies Can Be Treated With OIT?
OIT theoretically should work for any food allergy as long as the allergy is an IgE based allergic reaction (for example- Eosinophilic esophagitis can't be treated with OIT).
The different protocols for all the foods currently being treated, are all built off the same basic backbone used for desensitizing pretty much anything (food, medications etc.).
There are some questions one must pose before attempting OIT
1. Is the risk of OIT less (or equal) than not doing it. (risk vs. benefit)
2. Is there potential for
significant improvement of the quality of life. (You do not
want the cure to be worse than the disease.) Anxiety, time
involved with the procedure, even cost should be weighed. 3.
Other factors must be considered. Family dynamics, religious
beliefs, among others.
We currently have protocols for Peanut, Egg, Wheat, Soy,
Sesame Seed, Shrimp,
and Tree nut. Just about any food could be treated.
These references are only a small portion of articles used. Please go to the OIT article page, for a far more expansive list.
1. Oral Desensitization for Food Hypersensitivity. Immunol Allergy Clin N Am 31 (2011) 367–376.
2. Specific oral tolerance induction (SOTI) in pediatric age: clinical research or just routine practice? Pediatr Allergy Immunol. 2010 Mar;21(2 Pt 2):e446-9. Epub 2009 Jul 2.
Safety of a peanut oral immunotherapy protocol in children
with peanut allergy.
Journal of Allergy & Clinical Immunology. 124(2):286-91, 291.e1-6, 2009 Aug