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How does IgE help defend the body against parasites?

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Diagram of an antibody molecule showing two identical light chains and two identical heavy chains joined by disulfide bonds in a Y-shaped structure, with labeled regions for antigen binding and effector function. — antibody The four-chain structure of an antibody, or immunoglobulin, molecule. The basic unit is composed of two identical light (L) chains and two identical heavy (H) chains, which are held together by disulfide bonds to form a flexible Y shape. Each chain is composed of a variable (V) region and a constant (C) region.

IgE antibodies defend the body against large multicellular parasites through two primary mechanisms involving specialized immune cells.1

First, most IgE molecules bind to receptors on mast cells and basophils. When these IgE antibodies encounter a parasite, they trigger the cells to release pharmacologically active chemicals from their granules. This response increases local blood vessel permeability, activates platelets, induces smooth muscle contraction, and promotes fluid secretion. These actions collectively help dislodge parasites, such as hookworms, from the body.12

Second, IgE works in tandem with eosinophils to destroy parasites like the flatworms responsible for schistosomiasis. Eosinophils attach themselves to the IgE-coated worms and release granular chemicals that break down the parasite's tough protective skin. While IgE is also associated with allergic reactions, its specialized role in these defensive processes is critical for combating parasitic infections.132