What is a non-IgE (Immunoglobulin E) allergy?

From the Guidelines

A non-IgE allergy is an allergic reaction that occurs without the involvement of immunoglobulin E (IgE) antibodies, and the best management plan is to avoid ingesting the specific allergen or allergens, as recommended by the NIAID-sponsored expert panel 1. The diagnosis and management of non-IgE-mediated food allergy is similar to that of IgE-mediated food allergy, with considerations including medical history, age, and specific food allergen 1. Some key points to consider in non-IgE allergies include:

• The involvement of other immune mechanisms such as T-cells or other antibody types like IgG
• Common examples including certain food intolerances, contact dermatitis, and some drug reactions
• Delayed reactions appearing hours or days after exposure, manifesting as gastrointestinal issues, skin rashes, or respiratory symptoms
• Challenging diagnosis due to negative standard allergy tests like skin prick tests or RAST blood tests, which primarily detect IgE antibodies
• Management involving identifying and avoiding triggers, using medications to control symptoms, and in some cases, working with specialists to develop desensitization protocols, with food avoidance being the best management plan 1. It is essential to understand the difference between IgE and non-IgE allergies for proper diagnosis and treatment of allergic conditions, and to prioritize avoiding the specific allergen or allergens in non-IgE-mediated food allergy, as guided by the most recent and highest quality study 1.

From the Research

Definition of Non-IgE Allergy

• A non-IgE (Immunoglobulin E) allergy is an immune-mediated disease that can result in considerable morbidity and even mortality, with a significant negative impact on patients' quality of life 2.
• Non-IgE-mediated food allergies are characterized by delayed gastrointestinal (GI) manifestations that occur after exposure to an inciting food protein 3.

Types of Non-IgE-Mediated Food Allergies

• Several disorders are classified as non-IgE-mediated food allergies, including:
  • Food protein-induced enterocolitis syndrome (FPIES)
  • Food protein-induced allergic proctocolitis (FPIAP)
  • Food protein-induced allergic enteropathy (FPE)
  • Food protein-induced dysmotility disorders (GORD and constipation)
  • Eosinophilic esophagitis (EoE) 2, 3, 4

Clinical Manifestations and Diagnosis

• The symptoms of non-IgE-mediated food allergies can range from mild to severe and can be acute or chronic 2, 4.
• Diagnosis is usually made clinically, based on history and improvement of symptoms upon removal of the culprit food 2, 3, 5, 6.
• Food reintroduction should be attempted, with documentation of symptoms of relapse to confirm the diagnosis 2, 6.

Management and Prognosis

• Management includes dietary avoidance, supportive treatment in the case of accidental exposure, and nutritional counseling 2, 3, 6.
• The prognosis is generally favorable, with the majority of cases resolved before school age 6.
• Serial follow-up is essential to establish whether the acquisition of tolerance has occurred and to avoid unnecessary food restriction and potential consequent nutritional deficiencies 6.