CLT Food Sensitivities & Immunology Basics 3 — Questions and Answers
Question 1: Which of the following chemical mediators is a lipid-derived eicosanoid released from arachidonic acid during food sensitivity reactions?
- Histamine
- Serotonin
- Prostaglandin E2 (Correct answer)
- Substance P
Correct answer: Prostaglandin E2
Prostaglandin E2 is synthesized from arachidonic acid via the COX pathway and contributes to vasodilation, pain, and inflammation in food sensitivity reactions.
Question 2: In LEAP dietary therapy, the Phase 1 'LEAP diet' is constructed based on MRT results by:
- Eliminating the top 10 highest-volume foods consumed
- Eating only the least reactive foods identified by MRT (Correct answer)
- Rotating all moderately reactive foods every 4 days
- Removing all gluten- and dairy-containing foods universally
Correct answer: Eating only the least reactive foods identified by MRT
Phase 1 of the LEAP diet includes only the foods that showed the least reactivity on MRT, providing an anti-inflammatory dietary baseline.
Question 3: Leukotrienes released during a food sensitivity reaction are significant because they:
- Act only as vasoconstrictors in the skin
- Are 100–1000 times more potent than histamine at causing bronchoconstriction (Correct answer)
- Are exclusively produced by mast cells, not basophils
- Decrease vascular permeability
Correct answer: Are 100–1000 times more potent than histamine at causing bronchoconstriction
Cysteinyl leukotrienes (LTC4, LTD4, LTE4) are extremely potent bronchoconstrictors and play a key role in respiratory symptoms of food reactions.
Question 4: A delayed food sensitivity reaction appearing 3–72 hours after ingestion is most consistent with which immunological mechanism?
- IgE-mediated mast cell degranulation
- Non-IgE-mediated mediator release and cellular inflammation (Correct answer)
- Complement-mediated lysis
- Neutralizing antibody interference
Correct answer: Non-IgE-mediated mediator release and cellular inflammation
Delayed food sensitivity reactions reflect non-IgE pathways including IgG, IgA immune complexes, T cell responses, and direct mediator release that build over hours to days.
Question 5: Which of the following is a preformed mediator stored in granules and released immediately upon immune cell activation?
- Prostaglandin D2
- Platelet-activating factor
- Histamine (Correct answer)
- IL-6
Correct answer: Histamine
Histamine is preformed and stored in mast cell and basophil granules, enabling its immediate release within seconds of cell activation.
Question 6: The Th1/Th2 balance is clinically relevant in food sensitivities because an overactive Th2 bias:
- Promotes IFN-γ production and reduces inflammation
- Enhances IgE class switching and atopic sensitization (Correct answer)
- Suppresses B cell antibody production
- Drives cytotoxic CD8+ T cell responses
Correct answer: Enhances IgE class switching and atopic sensitization
A Th2-dominant immune environment favors IL-4/IL-13 production, which promotes IgE synthesis and increases susceptibility to allergic sensitization.
Question 7: MRT results are reported as a percentage change in cell volume. A result showing >20% change is typically interpreted as:
- Non-reactive — safe to include in Phase 1
- Moderately reactive — reintroduce cautiously in Phase 2
- Highly reactive — avoid during initial phases (Correct answer)
- Inconclusive — requires repeat testing
Correct answer: Highly reactive — avoid during initial phases
Foods producing greater than 20% volume change are classified as highly reactive on MRT and are excluded from the initial LEAP diet.
CLT Food Sensitivities & Immunology Basics 3
Which of the following chemical mediators is a lipid-derived eicosanoid released from arachidonic acid during food sensitivity reactions?