Final answer:
IgE is the antibody most involved in the allergic response. It binds to mast cells and triggers the release of histamines and other mediators.
Step-by-step explanation:
The antibody that is most involved in the allergic response is IgE. IgE is present in the serum in small quantities and is best characterized in its role as an allergy mediator. When an allergen is encountered for the first time, IgE antibodies are synthesized by plasma cells in response to the harmless antigen. On subsequent exposure to the allergen, the IgE antibodies bind to mast cells, triggering the release of histamines and other mediators, which cause the symptoms of allergy.