CHARACTERIZATION OF COMPLEX-FORMATION BY HUMANIZED ANTI-IGE MONOCLONAL-ANTIBODY AND MONOCLONAL HUMAN IGE

The interaction of human IgE with high-affinity IgE F-c receptors on cells of the immune system plays an essential role in the type I hypersensitivity reaction. A proposed therapy is to use an anti-IgE monoclonal antibody to block the binding of IgE to its high-affinity receptor on mast cells and basophils, thus preventing subsequent release of the inflammatory agents after exposure to allergen, We report here the solution characteristics of immune complexes formed by a humanized anti-IgE monoclonal antibody (rhuMAb E25) and IgE using sedimentation analysis and size exclusion chromatography. We demonstrate that the rhuMAb E25 is able to form a variety of complexes with IgE at different molar ratios, The largest complex was identified by sedimentation equilibrium analysis as a heterohexamer with very high stability, The intermediate complex formed when one of the interacting components is in large molar excess appears to have a trimeric structure. The high-affinity interaction of rhuMAb E25 and IgE has also been confirmed, Furthermore, by using hydrodynamic modeling, we show that the largest complex may be represented by a cyclic structure.