Omalizumab, an anti-IgE antibody used to treat severe allergic asthma and chronic idiopathic urticaria, binds to IgE in blood or membrane-bound on B lymphocytes, but not to IgE bound to its high (FcεRI) or low (CD23) affinity receptors in sensitized patients, which are ready to capture the allergens. Here, IGHE is linked to chronic idiopathic urticaria.