This response sensitizes the organism so that when itre-encounters the allergen, the allergen molecules are bound by specific IgE molecules on the surface of mast cells, causing them to undergo degranulation and to synthesize and release large quantities of allergic mediators (i.e., histamine, leukotriene, and platelet-activating factor), which then produce a local or systemic allergic reaction [17]. This evidence concerns the gene IGHE and allergic disease.