(656d) High-Throughput Analysis of Concentration-Dependent Antibody Self-Association

Monoclonal antibodies are typically monomeric and non-viscous at low concentrations, yet they display highly variable associative and viscous behavior at elevated concentrations. Although measurements of antibody self-association are critical for understanding this complex behavior, traditional biophysical methods are not capable of characterizing concentration-dependent protein self-association in a high-throughput manner. In this presentation, we will describe a nanoparticle-based method (self-interaction nanoparticle spectroscopy) capable of rapidly measuring concentration-dependent self-interactions for three human monoclonal antibodies with unique solution behaviors. We find that gold nanoparticles conjugated with antibodies at low protein concentrations display self-association behavior (as measured by the interparticle distance-dependent Plasmon wavelength) that is well correlated with static light scattering measurements obtained at orders of magnitude higher antibody concentrations. Using this methodology, we find that the several monoclonal antibodies display complex pH-dependent self-association behavior that is strongly influenced by the solution ionic strength. Importantly, we find that a polyclonal human antibody is non-associative for all solution conditions evaluated for the monoclonal antibodies, suggesting that antibody self-association is more specific than previously realized. We expect that our findings will accelerate the analysis of sequence and structural determinants of antibody self-interactions.