The human IgE network.

IgE and its receptors are believed to have evolved as a mechanism to protect mammals against parasites. But other and intrinsically innocuous antigens can subvert this system to provoke an allergic response. For human populations in industrialized countries, allergy and asthma now represent a far greater threat than parasitic infection, and the main impetus for current studies of the IgE system is the hope of understanding and intervening in the aetiology of allergic diseases.