Food Allergies Flashcards
(15 cards)
Food allergy vs. Food sensitization
- Food allergy initiates a specific immune response and has adverse health effects. Can be IgE-mediated or non-IgE mediated.
- Food sensitization means you have food-specific IgE (positive food allergy test) without symptoms or adverse health effects.
What are 3 most common food allergens in the USA?
milk, egg, peanut
Describe Allergen Sensitization (First Exposure)
Allergen Sensitization: The process by which the immune system will produce antibodies in response to first exposure with an allergen.
- First exposure of APCs to allergen
- Proliferation and differentiation of T cells –> Th2
- Th 2 response (IL-4, 5)
- Th2 assists in IgE class switching in B cells
- Plasma cells secrete IgE
- Binding of IgE to FceRI on mast cells/basophils
Describe Mast Cell/Basophils Activation (Repeat Exposure)
- Repeat exposure to allergen causes rapid activation of mast cell to release mediators.
- Mast cell degranulation includes the release of cytokines and vasoactive amines/lipids.
What kind of response is produced by vasoactive mediators (lipids/amines) released from the mast cells?
Immediate Type I hypersensitivity reaction (within minutes)
What kind of response is produced by cytokines released from the mast cells
Late phase reaction (within hours)
What is the receptor that has a high affinity for IgE and is highly expressed on mast cells and basophils?
FceRI (Fc epsilon receptor)
What cytokine is required for Mast Cell and Basophil Growth?
IL-3 (activates stem cell production)
What cytokine is produced by mast cell upon activation?
TNF
What leukocyte (besides mast cells/basophils) is recruited to tissues during late-phase of allergic/parasitic response?
Eosinophils
*Granule enzymes released by eosinophils are toxic to microbes but also toxic to host tissues.
What eicosanoids (vasoactive lipids) are produced by mast cells/basophils?
Prostaglandins (vasodilators)
leukotrienes (smooth muscle contraction)
What is the most important factor to consider before IgE diagnostic testing?
Patient History
Describe Oral Allergy Syndrome
aka. pollen-food allergy syndrome
Typically presents in ppl with allergic rhinitis. IgE-mediated reaction against pollen-related proteins in foods.
Describe Food-dependent exercise-induced anaphylaxis
Development of anaphylaxis during exercise that occurs after a few hours of eating a specific food.
Describe Delayed Mammalian Meat Allergy
aka. alpha gal syndrome
Allergy reaction begins hours after eating mammalian meat. Often begins when a lone start tick bites someone. Due to IgE for carbohydrate on meat (alpha-gal).
