From the Guidelines
An IgE allergy is a type of immediate hypersensitivity reaction where your immune system overreacts to normally harmless substances by producing immunoglobulin E (IgE) antibodies, as defined by the most recent clinical practice guideline on immunotherapy for inhalant allergy 1.
Definition of IgE Allergy
An IgE allergy occurs when your immune system produces IgE antibodies in response to exposure to an allergen, such as pollen, pet dander, certain foods, or insect venom. These IgE antibodies bind to mast cells and basophils, triggering the release of inflammatory chemicals like histamine, which causes classic allergy symptoms.
Key Characteristics of IgE Allergies
- Occur rapidly, usually within minutes of exposure
- Involve the specific antibody class IgE, which evolved to protect against parasitic infections but can mistakenly target harmless environmental substances
- Can cause a range of symptoms, from mild (hives, itching, swelling) to severe (anaphylaxis, a potentially life-threatening reaction)
Treatment Options for IgE Allergies
- Antihistamines like cetirizine (10mg daily), loratadine (10mg daily), or fexofenadine (180mg daily)
- Nasal corticosteroids like fluticasone (1-2 sprays per nostril daily)
- Allergen immunotherapy (allergy shots) in some cases
- Epinephrine (commonly via an EpiPen, typically dosed at 0.3mg for adults, 0.15mg for children) for severe reactions like anaphylaxis
Importance of Accurate Diagnosis and Treatment
Accurate diagnosis and treatment of IgE allergies are crucial to prevent unnecessary morbidity and mortality, as well as to improve quality of life for affected individuals, as emphasized in recent clinical practice guidelines 1.
From the Research
Definition of Immunoglobulin E (IgE) Allergy
- Immunoglobulin E (IgE) allergy is defined as an adverse immunologic response to a food or other substance, mediated by IgE antibodies 2, 3, 4.
- IgE-mediated reactions can involve various body systems, including the skin, gastrointestinal tract, respiratory tract, and cardiovascular system 3, 4.
Clinical Manifestations
- The clinical manifestations of IgE-mediated allergy can range from mild to severe and may include symptoms such as cutaneous and gastrointestinal symptoms, anaphylaxis, and oral allergy syndrome 2, 5, 4, 6.
- The onset of symptoms is usually rapid, occurring within minutes to a few hours after exposure to the allergen, although exceptions exist 2.
- The severity of symptoms is not predicted by the level of specific IgE or skin test wheal size, but the likelihood of symptom onset is directly related 4.
Diagnosis and Management
- Diagnosis of IgE-mediated allergy requires a careful history and diagnostic tests, which may include skin prick tests, serum-specific IgE, and oral food challenge 3, 4.
- Management of food allergies requires strict avoidance measures, counseling of the family about constant vigilance, and prompt treatment of allergic reactions with emergency medications 4.
- Future treatments for IgE-mediated food allergy being evaluated in clinical trials include epicutaneous, sublingual, and oral immunotherapy 4.
Types of Food Allergy
- Food allergy can be classified into two types (class 1 and class 2) based on the pathophysiological mechanism 6.
- Class 1 food allergens are generally heat-, enzyme-, and low pH-resistant glycoproteins, while class 2 food allergens are heat-labile and susceptible to digestion 6.
- Pollen-food allergy syndrome (PFAS) is a type of class 2 food allergy, where pollen allergy causes plant food allergy 6.