What is the function of IgE?

What is the function of IgE?

• A. Binds to allergens and triggers histamine release from mast cells and basophils; also involved in defense against parasitic worms.
• B. Neutralizes bacterial toxins.
• C. Main antibody of the late secondary immune response.
• D. Activates macrophage phagocytosis as its primary role.

Answer: (A)

IgE's main job is to drive immediate allergic reactions and help defend against parasitic worms. It binds with high affinity to receptors on mast cells and basophils, staying there ready to respond. When an allergen cross-links the IgE already bound on these cells, they degranulate and release histamine and other mediators, producing itching, swelling, redness, and, in the airways, bronchoconstriction. In parasitic infections, IgE coats the parasite and promotes eosinophil-mediated killing. This differs from antibodies that neutralize toxins or help with phagocytosis as their primary role (those are mainly IgG). So the described function—binding allergens and triggering histamine release from mast cells and basophils, plus involvement in defense against parasitic worms—best captures IgE’s role.

IgE's main job is to drive immediate allergic reactions and help defend against parasitic worms. It binds with high affinity to receptors on mast cells and basophils, staying there ready to respond. When an allergen cross-links the IgE already bound on these cells, they degranulate and release histamine and other mediators, producing itching, swelling, redness, and, in the airways, bronchoconstriction. In parasitic infections, IgE coats the parasite and promotes eosinophil-mediated killing. This differs from antibodies that neutralize toxins or help with phagocytosis as their primary role (those are mainly IgG). So the described function—binding allergens and triggering histamine release from mast cells and basophils, plus involvement in defense against parasitic worms—best captures IgE’s role.