Bacteriology USMLE Step 1 Practice Question
A 35 year old woman has severe seasonal allergic rhinitis that has not improved with antihistamines or intranasal glucocorticoids. She starts a program of repeated administration of gradually increasing doses of pollen extract. After several months she is able to spend time outdoors with minimal symptoms. Which of the following immunologic changes most likely mediates the benefit of this therapy?
Answer choices
- ADirect destruction of mast cells by cytotoxic T cells
- BIncreased production of allergen specific IgG that blocks allergen binding to IgE on mast cellsCorrect answer
- CGeneration of IgM that activates complement at mucosal surfaces
- DComplete elimination of memory B cells specific for the allergen
- ESuppression of all helper T cell function
- FExpansion of IL-4-secreting Th2 cells that downregulate IgE production
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