Evidence for intermolecular domain exchange in the Fab domains of dimer and oligomers of an IgG1 monoclonal antibody.

Recombinant protein therapeutics have become increasingly useful in combating human diseases, such as cancer and those of genetic origin. One quality concern for protein therapeutics is the content and the structure of the aggregated proteins in the product, due to the potential immunogenicity of these aggregates. Collective efforts have led to a better understanding of some types of protein aggregates, and have revealed the diversity in the structure and cause of protein aggregation.

Dimers and multimers of monoclonal IgG1 exhibit higher in vitro binding affinities to Fcgamma receptors.

The in vitro binding of monomeric, dimeric and multimeric forms of monoclonal IgG1 molecules, designated mAb1 and mAb2, to the extracellular domains of Fcgamma receptors RI, RIIA and RIIIB were investigated using a surface plasmon resonance (SPR) based biosensor technique. Stable noncovalent and covalent dimers of mAb1 and mAb2, respectively, were isolated from CHO cell expressed materials. The dissociation constants of monomeric mAb1 and mAb2 were determined to be 1 nM for the FcgammaRI-binding and 6-12 microM for the FcgammaRIIA- and FcgammaRIIIB-binding.