OIT or Oral Immunotherapy
OIT stands for Oral Immunotherapy, also known as food allergy desensitization. Oral desensitization is a method of re-training the immune system to tolerate the food allergen protein by consuming small, but gradually increased, amounts of the food. Over time, the body's allergic response to the allergen is diminished.
HOW DOES IT WORK?
The “allergic antibody,” known as IgE, causes hypersensitivity to a specific food, such as peanuts, when it is identified in the body. The body gradually increases the amount of a “protective blocking antibody” called IgG4. The IgG4 prevents the IgE antibody from triggering an allergic response. As a result of the desensitization process, the increase in the IgG4 blocking antibody eventually leads to a decrease in the “allergic antibody” IgE, which shifts the balance from hypersensitivity to tolerance within the body.
WHAT IS THE GOAL OF TREATMENT?
The goal of OIT is to prevent severe anaphylactic reactions arising from the accidental consumption of a food allergen; therefore significantly improving the quality of life of not only the individual with the food allergy but also the parents or other caregivers.
IS OIT A “CURE” FOR FOOD ALLERGIES?
No. OIT is a form of desensitization allowing individuals to eat the food without causing an allergic reaction. To maintain the desensitization, the food must be eaten on a daily basis even after the desensitization process has been completed. If the individual stops eating the food, the immune system will return to the original allergic state.
WHO ARE GOOD CANDIDATES FOR OIT?
Individuals who have experienced an allergic reaction after ingesting a food AND also have shown evidence of the allergy to that food on skin and/or blood testing. OIT only treats food allergies that are caused by the IgE allergic antibody. Individuals who lack this antibody on a skin or blood allergy test, will not benefit from OIT. It is not effective or intended for the treatment of food intolerances, Celiac disease, Eosinophilic Esophagitis (EoE), or Irritable Bowel Syndrome (IBS).
WHO ARE NOT CANDIDATES FOR OIT?
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Individuals with poorly controlled asthma, severe eczema and EoE.
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Those who are unable to comply with the required follow-up visits. OIT requires numerous visits for dose increases to be successful.
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Those who are uncomfortable, unwilling, or unable to inject epinephrine to themselves, or their child, in the event of anaphylaxis.
ARE THERE ANY AGE RESTRICTIONS?
OIT will only be offered to patients 4 years of age and older. The exact age that a child becomes a good candidate is dependent upon the child's ability to communicate to the parent/caregiver and healthcare provider in the event there is any type of reaction.
HOW EFFECTIVE IS OIT?
Very effective. In academic centers where rigid research protocols must be followed due to regulations, the success rate of oral immunotherapy is 80-90%. In contrast, allergists in private practice are able to customize and modify the protocols for each individual based on the sensitivity level of the allergy and the progress during the treatment. As a result, the success rate in private practices ranges is 95-100%. Treatment failures in private practices are typically due to lack of patient compliance.
HOW MANY VISITS TO THE ALLERGY OFFICE ARE THERE?
There are approximately 20-24 biweekly (every 2 weeks) appointments in the office. The exact duration will vary person to person depending on adjustments in dosage that may be necessary due to any reactions. The ability to individualize the protocol allows for maximization of safety, comfort and convenience.
There will be an initial consultation visit to discuss the OIT protocol in more detail and answer any questions.
The 1st treatment visit is called the Initial Dose Escalation Day (IDED). The IDED will be done to determine the initial home dose. We will carefully feed the individual a very small amount of the food allergen and observe for any reaction. The amount of food allergen given will approximately double every 20 to 30 minutes up to a maximum tolerated dose. This dose varies depending on the type of food allergen.
For example, with peanut allergen we will start with 0.01 mg peanut protein (in a solution form) given by mouth with a maximum dose goal of 3 mg of peanut protein by the end of the visit. Once the maximum tolerated dose is given, there will be a 1 to 2 hour observation period and if there are no reactions, the patient will be sent home. This visit will last 4 to 6 hours, or longer, if there are any reactions.
The 2nd visit is the day after the IDED. On this day the candidate will receive the maximum tolerated dose from the previous day and be observed for 1.5 to 2 hours. If there are no reactions, the candidate will be sent home.
After the 2nd visit, the maximum tolerated dose will be taken at home daily for 2 weeks. The candidate will then return to our office every 2 weeks to increase the dose of daily protein. Each dose escalation visit will last 1.5 to 2 hours. The initial doses will be given in a solution form, but there is a point in time with the home dosage may be given as the actual food (i.e. peanut or peanut butter). Our protocol is designed to reach a maintenance dose of 2 grams of protein (equivalent to 8 peanuts). It will take approximately 42 weeks (or possibly longer, depending on the individual’s progress) to reach this dose.
WHAT IS THE RISK OF AN ALLERGIC REACTION DURING OIT?
Studies show that most patients will exhibit symptoms at some point during the OIT process. Reactions more commonly occur during the dose escalation phase, although they can occur at any time during therapy. The majority of reactions are treated successfully with an antihistamine only. The most common reactions include an itchy mouth and mild abdominal pain and/or vomiting. A recent chart review of oral immunotherapy, with peanut conducted in 5 private allergy clinics, reported epinephrine use was uncommon (0.2-0.7 out of 1000 doses).
Although this is reassuring, the candidate must always have epinephrine readily accessible and follow their allergic reaction treatment plan.
WILL I HAVE TO EAT THE MAINTENANCE DOSE DAILY AND FOREVER?
For the immediate future, yes. However, ongoing studies are addressing safe ways to discontinue the maintenance dose without losing the acquired protection.