IgE, or immunoglobin E, belong to a specific category of antibodies of the mammal species, which includes, of course, humans. They are composed of a Y-shaped structure, and produced by plasmocytes that come from B-cells (lymphocytes). Once they are bound to the specific antigen they are programmed to destroy, these antibodies provoke a specifically-adapted reaction against the intrusion of this agent. It should be noted, however, that immunoglobin E can cause severe allergic reaction that can even be fatal. When in contact with certain allergens, IgE can cause anaphylactic shock due to an exaggerated immune response.