Xolair binds to IgE (a class of antibodies normally secreted in allergic responses), which prevents their binding to mast cells and basophils.
Xolair inhibits the binding of IgE to the high-affinity IgE receptor (FceRI) on the surface of mast cells and basophils. Reduction in surface-bound IgE on FceRI-bearing cells limits the degree of release of mediators of the allergic response. Xolair is used to treat severe, persisten asthma.
Most likely removed by opsonization via the reticuloendothelial system.