Which immunoglobulin class is most closely associated with anaphylaxis?

Which immunoglobulin class is most closely associated with anaphylaxis?

• A. IgA
• B. IgG
• C. IgM
• D. IgE

Answer: (D)

Anaphylaxis is a rapid, life-threatening allergic reaction driven by IgE antibodies. When a sensitized person is exposed again to the allergen, the allergen binds to IgE already attached to the high‑affinity FcεRI receptors on mast cells and basophils, causing IgE cross-linking. This triggers degranulation and release of histamine and other mediators, leading to sudden vasodilation, fluid leakage, and bronchoconstriction that produce the symptoms of anaphylaxis. Other antibody classes have different roles—IgA focuses on mucosal defense, IgG on systemic neutralization and opsonization, and IgM is the initial responder in primary infections—so IgE is the one most closely tied to this severe allergic reaction.

Anaphylaxis is a rapid, life-threatening allergic reaction driven by IgE antibodies. When a sensitized person is exposed again to the allergen, the allergen binds to IgE already attached to the high‑affinity FcεRI receptors on mast cells and basophils, causing IgE cross-linking. This triggers degranulation and release of histamine and other mediators, leading to sudden vasodilation, fluid leakage, and bronchoconstriction that produce the symptoms of anaphylaxis. Other antibody classes have different roles—IgA focuses on mucosal defense, IgG on systemic neutralization and opsonization, and IgM is the initial responder in primary infections—so IgE is the one most closely tied to this severe allergic reaction.