Food Allergies

Question 1

Food allergy vs. Food sensitization

Answer 1

• 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.

Question 2

What are 3 most common food allergens in the USA?

Answer 2

milk, egg, peanut

Question 3

Describe Allergen Sensitization (First Exposure)

Answer 3

Allergen Sensitization: The process by which the immune system will produce antibodies in response to first exposure with an allergen.

1. First exposure of APCs to allergen
2. Proliferation and differentiation of T cells –> Th2
3. Th 2 response (IL-4, 5)
4. Th2 assists in IgE class switching in B cells
5. Plasma cells secrete IgE
6. Binding of IgE to FceRI on mast cells/basophils

Question 4

Describe Mast Cell/Basophils Activation (Repeat Exposure)

Answer 4

1. Repeat exposure to allergen causes rapid activation of mast cell to release mediators.
2. Mast cell degranulation includes the release of cytokines and vasoactive amines/lipids.

Question 5

What kind of response is produced by vasoactive mediators (lipids/amines) released from the mast cells?

Answer 5

Immediate Type I hypersensitivity reaction (within minutes)

Question 6

What kind of response is produced by cytokines released from the mast cells

Answer 6

Late phase reaction (within hours)

Question 7

What is the receptor that has a high affinity for IgE and is highly expressed on mast cells and basophils?

Answer 7

FceRI (Fc epsilon receptor)

Question 8

What cytokine is required for Mast Cell and Basophil Growth?

Answer 8

IL-3 (activates stem cell production)

Question 9

What cytokine is produced by mast cell upon activation?

Answer 9

TNF

Question 10

What leukocyte (besides mast cells/basophils) is recruited to tissues during late-phase of allergic/parasitic response?

Answer 10

Eosinophils

*Granule enzymes released by eosinophils are toxic to microbes but also toxic to host tissues.

Question 11

What eicosanoids (vasoactive lipids) are produced by mast cells/basophils?

Answer 11

Prostaglandins (vasodilators)

leukotrienes (smooth muscle contraction)

Question 12

What is the most important factor to consider before IgE diagnostic testing?

Answer 12

Patient History

Question 13

Describe Oral Allergy Syndrome

Answer 13

aka. pollen-food allergy syndrome

Typically presents in ppl with allergic rhinitis. IgE-mediated reaction against pollen-related proteins in foods.

Question 14

Describe Food-dependent exercise-induced anaphylaxis

Answer 14

Development of anaphylaxis during exercise that occurs after a few hours of eating a specific food.

Question 15

Describe Delayed Mammalian Meat Allergy

Answer 15

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).