IgE Diseases

IgE production is a unique characteristic of mammals. Traditionally, the concept of allergy implied an abnormal response to an otherwise benign agent (eg, pollen or food), with an easily identifiable relationship between exposure and disease. However, there are syndromes in which the relationship between exposure to the relevant allergen and the "allergic" disease is not clear. In these cases, the presence of specific IgE antibodies can play an important role in identifying the relevant allergen and provide a guide to therapy. IgE is the antibody isotype found at the lowest concentration in the circulation. However, IgE can undeniably play an important role in mediating allergic reactions; best exemplified by the clinical benefits of anti-IgE monoclonal antibodies therapy for some allergic diseases. IgE has also been implicated in congenital diseases due to specific molecular defects and in autoimmune diseases behaving as a self-reactive immunoglobulin. This review will describe our current understanding of the interactions between IgE and its main receptors Fc ε RI and CD23 (Fc ε RII). We will review the known and potential functions of IgE in health and disease: in particular, its detrimental roles in allergic diseases and, its protective functions in host defense against parasites and venoms. Finally, we will present an overview of the drugs that are in clinical development or have therapeutic potential for IgE-mediated allergic diseases.