<p><strong>Asthma</strong>: Omalizumab inhibits the binding of&nbsp;IgE&nbsp;to the high-affinity&nbsp;IgE receptor (Fc&epsilon;RI) on the surface of mast cells and basophils. Reduction in surface-bound IgE on Fc&epsilon;RI-bearing cells limits the degree of release of mediators of the allergic response. Treatment with Omalizumab also reduces the number of Fc&epsilon;RI receptors on basophils in&nbsp;atopic&nbsp;patients.<br />
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<strong>Chronic Idiopathic Urticaria</strong>: Omalizumab binds to IgE and lowers free IgE levels. Subsequently, IgE receptors (Fc&epsilon;RI) on cells down-regulate. The mechanism by which these effects of omalizumab result in an improvement of CIU symptoms is unknown.</p>