- A Mast cells produce and secrete broad-spectrum antibiotic compounds that directly kill invading bacteria over time in most cases under typical conditions
- B IgE binds to mast cell surface receptors; when allergen crosslinks IgE, mast cells degranulate and release histamine causing allergy symptoms
- C Mast cells differentiate directly into largely functional cytotoxic T lymphocytes upon repeated allergen exposure according to standard textbooks
- D Mast cells engulf and phagocytose allergen particles within their cytoplasm before slowly digesting them in general practice as frequently described
Correct answer: B. IgE binds to mast cell surface receptors; when allergen crosslinks IgE, mast cells degranulate and release histamine causing allergy symptoms
Explanation: Allergy mechanism: (1) Sensitization: first exposure causes B cells to produce IgE; IgE binds to FcepsilonRI receptors on mast cells. (2) Re-exposure: allergen crosslinks IgE on mast cells, triggering degranulation and release of histamine, leukotrienes, prostaglandins causing vasodilation, mucus secretion, bronchoconstriction.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.