Anti-IgE for the treatment of allergic rhinitis--and eventually nasal polyps?

In allergic rhinitis, cross-linking of IgE molecules upon allergen contact induces degranulation of mast cells and basophils within the mucosal tissue and results in the release of typical mediators, which consecutively induce the well-known symptoms. Omalizumab counteracts these interactions by reducing serum levels of free IgE. Therapy targeted at IgE also interferes with its binding to the low-affinity receptors inhibiting the amplification of the Th(2)-type response. Treatment of allergic rhinitis with anti-IgE has been shown to be safe and to reduce specific symptoms. Furthermore, the combination of omalizumab with specific immunotherapy may not only increase efficacy but also safety in selected patients. Therefore, we reviewed previously published studies on omalizumab therapy in allergic rhinitis, either as monotherapy or in combination with immunotherapy. In patients with nasal polyps, a local multiclonal IgE response has recently been described, initiated by Staphylococcus aureus-derived enterotoxins, which at least modifies the inflammatory reaction within the tissue. Evidence accumulates that these enterotoxins act as superantigens resulting in a multiclonal T- and B-cell activation with massive IgE formation within the airways. Because of the multiclonality, a range of allergens could possibly maintain a constant degranulation of mast cells present in the polyp tissue, which may contribute to disease severity. We here discuss a proof-of-concept treatment trial with omalizumab in nasal polyposis, which--in case of a positive therapeutic response--would also pave the way for anti-IgE treatment approaches for severe non-atopic lower airway disease.