IgE-Mediated Allergic Reactions

So, what causes them? Food allergy is not the only type of IgE-mediated reaction or disease.

We will go through the five types of reactions/diseases that are IgE-mediated. It's important to first point out that all IgE-mediated responses involve mast cell degranulation, even though symptoms can vary depending on route of entry, as you will see below.

1. Systemic Anaphylaxis

Common Stimuli: Drugs, venoms, foods

Route of entry: Intravenous, which can occur either directly through an IV needle for example, or after oral ingestion, when the substance is then absorbed into the blood

Immune System Response: Swelling, increased vascular permeability (where blood vessels allow small cells to flow in and out), circulatory collapse, and sometimes death

2. Acute urticaria

Common Stimuli: Post-viral, animal hair, bee stings, skin prick testing for allergies

Route of entry: Through the skin, sometimes systemic

Immune System Response: Local increase in blood flow, vascular permeability and swelling

3. Seasonal rhino conjunctivitis

Common Stimuli: Pollens, dust mites

Route of entry: Contact with eyes or nose

Immune System Response: Swelling of eyes or nose, sneezing

4. Asthma

Common Stimuli: Dander, pollens, dust mites (sound familiar?)

Route of entry: Inhalation leading to contact with lining of the lower airways (that's the difference!)

Immune System Response: Bronchial constriction, increased mucus production, airway inflammation

5. Food Allergy

Common Stimuli: We know that the top eight food allergens are peanut, tree nuts, shellfish, fish, milk, eggs, soy and wheat, but there are over 100 foods a person can be allergic to

Route of entry: Oral

Immune System Response: Vomiting, Diarrhea, Itching, Hives, and sometimes systemic anaphylaxis mentioned in number 1 above

As you can see, although all of these reactions are IgE-mediated, the symptoms can vary depending on how the allergen comes into contact with our mucosal membranes. Symptoms can highly depend on whether the allergen is injected directly into the bloodstream, is eaten, or comes in contact with mucosal membranes such as the eyes, nose or respiratory tract.

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Have questions? Email them to me at info@nonuts4me.com

Information taken from:

Janeway's Immunobiology Textbook, 9th edition, Chpt. 14: Allergy and Allergic Diseases