A patient develops seasonal allergic rhinitis (hay fever). If a previously unexposed individual encounters pollen, which consequence becomes most likely following initial sensitization?

💡 Explanation

Initial pollen exposure causes B-cell activation and class switching to produce IgE antibodies specific to pollen antigens. These IgE antibodies then bind to mast cells and basophils via the FcεRI receptor. Because of this IgE sensitization, therefore, subsequent exposure triggers mast cell degranulation and histamine release, rather than other immediate immune responses.

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