Solution pH That Minimizes Self-Association of Three Monoclonal Antibodies Is Strongly Dependent on Ionic Strength
journal contributionposted on 02.04.2012, 00:00 by Shantanu V. Sule, Jason K. Cheung, Valentyn Antochshuk, Amardeep S. Bhalla, Chakravarthy Narasimhan, Steven Blaisdell, Mohammed Shameem, Peter M. Tessier
Monoclonal antibodies display highly variable solution properties such as solubility and viscosity at elevated concentrations (>50 mg/mL), which complicates antibody formulation and delivery. To understand this complex behavior, it is critical to measure the underlying protein self-interactions that govern the solution properties of antibody suspensions. We have evaluated the pH-dependent self-association behavior of three monoclonal antibodies using self-interaction chromatography for a range of pH values commonly used in antibody formulations (pH 4.4–6). At low ionic strength (<25 mM), we find that each antibody is more associative at near-neutral pH (pH 6) than at low pH (pH 4.4). At high ionic strength (>100 mM), we observe the opposite pH-dependent pattern of antibody self-association. Importantly, this inversion in self-association behavior is not unique to multidomain antibodies, as similar pH-dependent behavior is observed for some small globular proteins (e.g., ribonuclease A and α-chymotrypsinogen). We also find that the opalescence of concentrated antibody solutions (90 mg/mL) is minimized at low ionic strength at pH 4.4 and high ionic strength at pH 6, in agreement with the self-interaction measurements conducted at low antibody concentrations (5 mg/mL). Our results highlight the complexity of antibody self-association and emphasize the need for systematic approaches to optimize the solution properties of concentrated antibody formulations.