An anaphylactic reaction occurs due to which type of immune interaction?

• A. toxin-exotoxin interaction
• B. sympathetic-parasympathetic interaction
• C. alpha-beta interaction
• D. antigen-antibody interaction

Answer: (D)

Anaphylaxis is driven by an IgE-mediated antigen-antibody interaction. In someone prone to allergies, exposure to a specific allergen causes B cells to produce IgE antibodies that attach to mast cells and basophils. When the allergen is encountered again, it cross-links these IgE molecules, triggering rapid degranulation and release of histamine and other mediators. This mediator surge leads to sudden vasodilation, increased vascular permeability, bronchoconstriction, and airway edema, producing the severe, life-threatening symptoms of anaphylaxis. Other options describe toxin effects, autonomic nervous system actions, or non-immune receptor interactions, none of which explain this immediate, antibody-driven reaction.