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 c ells of the immune system plays an essential role in the type I hypers ensitivity reaction. A proposed therapy is to use an anti-IgE monoclon al 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 so lution characteristics of immune complexes formed by a humanized anti- IgE monoclonal antibody (rhuMAb E25) and IgE using sedimentation analy sis 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 equilibri um analysis as a heterohexamer with very high stability, The intermedi ate complex formed when one of the interacting components is in large molar excess appears to have a trimeric structure. The high-affinity i nteraction 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.