Which type of hypersensitivity reaction is IgE-mediated, such as anaphylaxis and urticaria?

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Multiple Choice

Which type of hypersensitivity reaction is IgE-mediated, such as anaphylaxis and urticaria?

The main idea is that immediate, IgE-driven reactions cause quick symptoms like anaphylaxis and hives. In this pathway, exposure to an allergen prompts B cells to produce IgE that sticks to mast cells and basophils. When the same allergen appears again, it cross-links those IgE molecules, triggering rapid degranulation and release of histamine and other mediators. This leads to vasodilation, swelling, and smooth muscle contraction, especially in the airways, within minutes. That’s the hallmark of IgE-mediated hypersensitivity, also known as immediate-type hypersensitivity. Other hypersensitivity types involve antibodies against cells (cytotoxic), immune complexes depositing in tissues (immune complex-mediated), or T-cell–mediated delayed responses, which operate by different mechanisms and on different timescales.

The main idea is that immediate, IgE-driven reactions cause quick symptoms like anaphylaxis and hives. In this pathway, exposure to an allergen prompts B cells to produce IgE that sticks to mast cells and basophils. When the same allergen appears again, it cross-links those IgE molecules, triggering rapid degranulation and release of histamine and other mediators. This leads to vasodilation, swelling, and smooth muscle contraction, especially in the airways, within minutes. That’s the hallmark of IgE-mediated hypersensitivity, also known as immediate-type hypersensitivity. Other hypersensitivity types involve antibodies against cells (cytotoxic), immune complexes depositing in tissues (immune complex-mediated), or T-cell–mediated delayed responses, which operate by different mechanisms and on different timescales.

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