Food Allergy Center of Excellence

Defining Food Allergy and its Mechanism of Cause

Food allergy is a medical condition that occurs when the body's natural defenses are over-stimulated in response to the exposure of a specific allergen. ² The mechanism of cause for food allergy is when the immune system attacks proteins in foods that are usually not problematic for most people and releases chemicals to defend against the offending aliergen. ¹ lt is estimated that 32 million Americans have food allergies, 5.6 million of those being children under the age of 18. ²

Common Food Allergens

Currently, the top eight food allergens in the United States are peanuts, milk, egg, tree nuts, wheat, soy, fish, and crustacean shellfish. These are the food allergens responsible for approximately 90% of all serious allergic reactions. Sesame seed allergy is increasing in prevalence and is generally acknowledged as the 9 ^th most common food allergen. ^2,3

What is Oral Immunotherapy (OIT)

One of the first accounts of oral immunotherapy date back to 1908 for the treatment of egg allergy. Patients ingested increasing amounts of their food allergen in order to alter their natural immune response and become "desensitized" to the offending allergen. ⁴

PATHOPHYSIOLOGY
T-Helper cells of the immune system are the key players of the allergic response in patients who suffer from food allergies. These T helper cells work alongside B cells to produce IgE antibodies targeted to a food allergen, When the body is exposed to the food allergen, the IgE antibodies recognize the invader and cause the allergic cells (i.e. mast cells and basophils) to release their contents and produce the typical symptoms of food allergy. This mechanism subsequently drives a desensitization state (tolerance) to a specific food allergen through a decline in T-Helper cell activity and interleukin-10 (an anti-inflammatory cytokine) production, which alters the IgE/lgG (immune antibodies) ratio. OIT is considered an adaptive form of immunity. ⁵

Oral Immunotherapy Treatment

One of the most important aspects of treatment is defining a goal such as preventing anaphylaxis and/or eating what the patient desires without hesitation. There are three definitive phases of oral immunotherapy treatment, First, the initiation phase is the patient's initial encounter when he or she is exposed to small amounts of the food allergen in increasing doses while in the clinic under direct observation. The second phase is the escalation phase , which emphasizes the continuation of increasingly larger doses of the allergen. The maintenance phase is the third and final phase of OIT treatment. In this phase, the patient consumes the allergenic food daily, Several studies have shown the desensitized state being accomplished in 4-6 months.

OIT Side Effects and Potential Risks

Potential side effects of OIT are abdominal cramping, abdominal pain, and/or nausea and vomiting. Other reported side effects are oral itching, hives, rash, wheezing, and swelling of the lips and/or throat. ⁶ A minority of patients (3-15%) develop eosinophilic esophagitis, which typically resolves at the completion of treatment. ⁴ Patients undergoing oral immunotherapy should always have injectable epinephrine and diphenhydramine (Benadryl) available!

Anaphylaxis
Anaphylaxis is a severe and potentially life-threatening allergic reaction. This reaction has a sudden onset (generally within 5-30 minute but may occur up to 2-6 hours later) and is a systemic response. Anaphylaxis may begin with mild symptoms such as rash, oral itching, or vomiting and may progress quickly to more severe symptoms such as difficulty breathing, chest tightness, difficulty swallowing, diarrhea, vomiting, rapid and faint heart rate, or cardiac arrest. ^7,8 It is vital for patients undergoing OIT to always have their epinephrine devices available!

Efficacy of Oral Immunotherapy

Approximately 80% of patients have been successfully desensitized to peanut, egg, and milk in clinical studies. ⁶ Multiple trials have been conducted utilizing quality of life surveys and the positive outcomes are impressive. ^4,6 Oral immunotherapy may provide protection against accidental food allergen exposures and has shown to have a significant improvement on the quality of life in food allergic patients.

Please contact the Food Allergy Center for Excellence at (806) 799-4192 for more information or if you are interested in OIT. Our providers will assist you with all your food allergy needs and answer any questions you may have! We strive to restore quality of life and decrease anxiety for patients and their families who have food allergies.

References