High Quality Content by WIKIPEDIA articles! Immunoglobulin E (IgE) is a class of antibody (or immunoglobulin "isotype") that has been found only in mammals. IgE is a monomeric antibody with 4 Ig-like domains (CH1->CH4). It plays an important role in allergy, and is especially associated with type 1 hypersensitivity. IgE has also been implicated in immune system responses to most parasitic worms like Schistosoma mansoni, Trichinella spiralis, and Fasciola hepatica, and may be important during immune defense against certain protozoan parasites such as Plasmodium falciparum.