IGHE and anaphylaxis: Upon re-exposure to the same allergenic protein, the allergen-specific IgE bound to FcεRI on mast cells will bind to the allergenic protein, triggering mast cell degranulation and the subsequent release of mediators such as histamine, tryptase, leukotrienes, and prostaglandins, causing symptoms of food anaphylaxis, such as nausea, vomiting, constriction of airways, hives, itching, and low blood pressure (3).