In vitro impact of anti-immunoglobulin E monoclonal antibodies, including omalizumab on whole blood basophil histamine release: Assessment of direct induction of basophil histamine release and evaluation of modulation of allergen-induced basophil histamine release.

AIM: The aim of this study was to evaluate the potential of anti-immunoglobulin E (IgE) and/or anti-IgE-IgE immune complexes to release histamine from peripheral blood basophils. In addition, a potential modulating effect of anti-IgE-IgE complexes on allergen-induced peripheral blood basophil histamine release was evaluated.

METHODS: Whole blood basophil histamine release (WBB-HR) tests done by using glass-fiber-based microtiter plates were performed in 62 patients with allergic rhinitis and/or asthma sensitized to perennial allergens. Evaluation of the direct effects of monoclonal anti-IgEs, including E25, E27, and QGE031, on WBB-HR, and the indirect effects of anti-IgE-serum IgE complexes on spontaneous and allergen-induced WBB-HR were conducted. The tests were performed with and without pretreatment of the basophils with interleukin 3, and the results were expressed as the fraction of total histamine content released.

RESULTS: There was no difference between WBB-HR induced by any of the studied anti-IgE antibodies and that induced by isotype antibodies for all blood samples assessed, which, for each patient, was significantly less than that induced by positive anti-IgE control antibodies. Similarly, no effect of any of the studied anti-IgE-IgE complexes on spontaneous or allergen-induced WBB-HR could be demonstrated.

CONCLUSION: There was no evidence that humanized, monoclonal anti-IgE antibodies E25 (omalizumab), E27, or QGE031 directly or indirectly induced histamine release from peripheral blood basophils.