The complement system is a mechanism used by antibodies to eliminate pathogens and cancer cells in the body. It is a collection of small proteins in the blood that usually circulate as inactive precursors. C1q is the first part of the classical complement pathway. IgG1, IgG2, IgG3, and IgM can fix complement and initiate the classical pathway. However, the activation of the complement cascade is strictly controlled and only occurs when the antibody binds to its antigen. The activation of the C1 complex (consisting of a single C1q molecule and two C1r and C1s molecules) that occurs when C1q binds to multiple immunoglobulin (IgG) molecules complexed with an antigen is highlighted by the C1q binding assay.
We provide additional C1q binding assays to support the production, process development, characterization, and similarity studies of therapeutic antibodies and Fc fusion proteins. Our scientists work with you to apply the C1q binding assay method that has been qualified by commercially available therapeutic monoclonal antibodies to demonstrate performance, and can specifically verify or qualify your products.