66 - Clinical Significance of Immunoglobulin E

Abstract

Immunoglobulin E (IgE) is central to the pathogenesis of many allergic diseases and is important in defense against some parasitic diseases. IgE bound to its high-affinity receptor (FcεRI) on the surface of mast cells and basophils is critical in allergen-induced degranulation, whereas antigen presentation occurs via the low-affinity receptor (FcεRII). With the shortest half-life of all immunoglobulin isotypes, serum IgE concentrations can change in days or weeks to reflect the balance of immune functions. IgE production is normally highly regulated, resulting in minimal IgE concentration in body fluids. Most of the IgE-producing plasma cells are found in the lymphoid tissue (gastrointestinal tract and respiratory tract) with the highest concentration in tonsils and adenoids. IgE is not transferred across the placenta, and levels increase from birth and peak by age 20 years. Total and specific IgE levels are frequently measured by a florescence immunoassay. Increased total serum IgE is seen in allergic diseases, some primary immunodeficiencies, parasitic and viral infections, certain inflammatory diseases, and with specific environmental and occupational exposures.