[Campbell Biology P.1019] Which of the following accurately describes a step in an IgE-mediat... | Practice Question

Which of the following accurately describes a step in an IgE-mediated allergic reaction upon second exposure to an allergen, according to the provided text and figure?

  • A: Plasma cells directly release histamine in response to the allergen.
  • B: IgE antibodies, attached to mast cells, are cross-linked by the allergen, leading to histamine release.
  • C: T cells directly recognize the allergen and trigger an inflammatory response.
  • D: Mast cells produce IgE antibodies that then bind to the allergen.

Explanation

IgE antibodies, upon initial exposure to an allergen, bind to receptors on mast cells. On subsequent exposure, the allergen cross-links these IgE molecules on the mast cell surface. This cross-linking triggers the mast cell to degranulate and release histamine and other inflammatory chemicals, leading to allergic symptoms.