PURPOSE: Interaction of @entity1 IgE with its high affinity receptor ( @entity220 ) on mast cells and basophils is an important step for initiating IgE mediated immune responses. To characterize the IgE and @entity220 interaction, we investigated this interaction in terms of stoichiometry and binding affinity in solution. The binding of IgE and IgE @entity220 chain, the extracellular portion of IgE high affinity receptor (sFc epsilon RI alpha) was compared with the binding of IgE and IgE immunoadhesin ( @entity220 -IgG). METHODS: The interaction was characterized by analytical ultracentrifugation, size exclusion chromatography, light scattering and ELISA. RESULTS: We show that the sFc epsilon RI alpha is only able to bind to one IgE, while the immunoadhesin can bind to two IgE. The interaction between IgE and @entity220 is very strong. Both forms of soluble receptors have similar intrinsic binding affinity with IgE. CONCLUSIONS: Both soluble receptors ( @entity220 alpha-IgG and sFc epsilon RI alpha) can block the binding of IgE to its high affinity receptors on cell surface. The @entity220 -IgG is a better IgE binding protein than sFc epsilon RI alpha at physiological relevant conditions. A humanized anti-IgE monoclonal antibody, rhuMAb E25 that also can block the binding of IgE to its high affinity receptors appears to bind to IgE at slightly different regions or in a different manner as the soluble forms of IgE receptors.

Interaction of XXXX IgE with soluble forms of IgE high affinity receptors.

@entity1 :: ('9606', 'Species') :: ['human'] @entity220 :: ('2205', 'Gene') :: ['Fc epsilon RI', 'Fc epsilon RI alpha']
@entity1 :: (9606,Species) :: ['human']
