Which feature is associated with anaphylaxis?

Which feature is associated with anaphylaxis?

• A. Buildup of IgE on mast cells
• B. Activation of complement
• C. Increase in cytotoxic T cells
• D. Large amount of circulating IgG

Answer: (A)

Anaphylaxis is driven by IgE-mediated activation of mast cells and basophils. When an allergen binds to IgE already attached to FcεRI receptors on these cells, the IgE molecules cross-link, triggering rapid degranulation and release of mediators like histamine, leukotrienes, and prostaglandins. These mediators cause vasodilation, increased vascular permeability, bronchoconstriction, and, in severe cases, shock. This IgE-bound mast cell degranulation is the feature that best fits the immediate, systemic reaction seen in anaphylaxis, so the buildup of IgE on mast cells is the best answer. Activation of complement can contribute to symptoms in some reactions but is not the defining trigger of classic IgE-mediated anaphylaxis. A rise in cytotoxic T cells is not central to this immediate hypersensitivity, and large amounts of circulating IgG are not the primary driver of typical anaphylaxis.

Anaphylaxis is driven by IgE-mediated activation of mast cells and basophils. When an allergen binds to IgE already attached to FcεRI receptors on these cells, the IgE molecules cross-link, triggering rapid degranulation and release of mediators like histamine, leukotrienes, and prostaglandins. These mediators cause vasodilation, increased vascular permeability, bronchoconstriction, and, in severe cases, shock. This IgE-bound mast cell degranulation is the feature that best fits the immediate, systemic reaction seen in anaphylaxis, so the buildup of IgE on mast cells is the best answer. Activation of complement can contribute to symptoms in some reactions but is not the defining trigger of classic IgE-mediated anaphylaxis. A rise in cytotoxic T cells is not central to this immediate hypersensitivity, and large amounts of circulating IgG are not the primary driver of typical anaphylaxis.