IGHE and allergic disease: Cross-linking of FcεRI-bound IgE to multivalent antigen (allergen), at the surface of basophils and/or mast cells, induces their activation and the release of pro-inflammatory molecules including vasoactive compounds (histamine), lipid mediators (prostaglandins, leukotrienes) and Th2 cytokines (like IL-4 and IL-13) that promote the development of a local or systemic allergic reaction (anaphylaxis) that can be lethal.