Methods for determining binding of an analyte to a receptor

摘要

A variant of a polypeptide comprising a human IgG Fc region is described, which variant comprises an amino acid substitution at amino acid position 329, or at two or all of amino acid positions 329, 331 and 322 of the human IgG Fc region. Such variants display altered effector function. For example, C1q binding and/or complement dependent cytotoxicity (CDC) activity may be reduced or abolished in the variant polypeptide. The application also describes an immune complex and an assay for determining binding of an analyte, such as an Fc region-containing polypeptide, to a receptor.