Later on, it was recognized that MCs (1) express a high-density of the high-affinity IgE receptor, FcεRI, (2) bind soluble immunoglobulin E (IgE) antibodies, which are produced by B cells after sensitization to a specific allergen, and (3) are the main deposit of histamine, the bioactive amine, driving allergic reactions and anaphylaxis [17,18]. Here, IGHE is linked to anaphylaxis.