Characterization of complex formation by humanized anti-IgE monoclonal antibody and monoclonal human IgE.
The interaction of human IgE with high-affinity IgE Fc 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.
Liu
J
J
Genentech, Inc., South San Francisco, California 94080, USA.
Lester
P
P
Builder
S
S
Shire
S J
SJ
D000888:Antibodies, Anti-Idiotypic / Q000737:chemistry / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism*; D000936:Antigen-Antibody Complex / Q000737:chemistry; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry / Q000378:metabolism*; D046911:Macromolecular Substances; D008433:Mathematics; D008958:Models, Molecular; D008970:Molecular Weight; D014461:Ultracentrifugation
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D046911:Macromolecular Substances; D007073:Immunoglobulin E