Anti-IgE therapy: clinical utility and mechanistic insights.

As the major trigger of acute allergic reactions, IgE has long been considered an ideal target for anti-allergy treatments. Omalizumab, first approved by the USA in 2003 and now in use in many other countries is a humanized monoclonal antibody that binds serum IgE. Anti-IgE therapy using omalizumab reduces circulating free IgE levels and blocks both early and late-phase reactions to allergen challenge. It has proven effective for allergic asthma and is currently being evaluated for use in a number of other atopic conditions including allergic rhinitis and chronic idiopathic urticaria. Clinical observations and mechanistic studies with omalizumab have shed new light on the multifaceted roles of IgE in immune homeostasis and in allergic disease.