ABSTRACT
Immunoglobulin (Ig) E-mediated hypersensitivity reactions are also known as immediate hypersensitivity reactions because of the short time lag (seconds to minutes) between antigen exposure and the onset of clinical symptoms. This is because the initial symptoms of immediate hypersensitivity depend on the release of preformed mediators stored in cytoplasmic granules of basophils and mast cells; the release is triggered by the cross-linking of membrane-bound IgE with the corresponding antigen (also known as allergen, by being involved in allergic reactions).
