IgE is a key molecule involved in immediate hypersensitivity and plays a major role in the pathogenesis of allergic diseases. Recently, a therapy based on the use of anti-IgE antibody has been developed by a pharmaceutical company, Genentech. A number of clinical trials have demonstrated that these antibodies are efficacious in treatment of allergies, including allergic rhinitis and asthma. The medication Omalizumab (Xolair) has recently been approved by the FDA for treatment of asthma.