Q- A 40-year-old woman comes to the physician because of a runny nose, sneezing, and itching eyes on exposure to cats since childhood. Anti-allergy drugs have not provided relief. Her symptoms improve with a program of desensitization involving administration of increasing doses of the allergen.
Which of the following is the most likely mechanism of the beneficial effect of this treatment?
(A) Formation of dimers that stimulate clearance by macrophage phagocytosis
(B) Increased production of IgG antibodies that block allergen binding to mast cells
(C) Overwhelming IgE binding sites to result in inactivation of mast cells
(D) Production of an anti-idiotypic antibody to IgE that results in its clearance
(E) Stimulation of macrophages to produce anti-inflammatory cytokines
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Answer and Explanation
This is a classic case of allergic rhinitis triggered by exposure to cat allergens. Her symptoms improve with allergen-specific immunotherapy (desensitization therapy), which involves repeated administration of increasing doses of the allergen to modify the immune response.
Allergen-specific desensitization therapy works by promoting IgG antibody production, which competes with IgE for allergen binding and prevents mast cell degranulation.
The correct answer is B