Antibody association in solution: cluster distributions and mechanisms

ABSTRACT

Understanding factors that affect the clustering and association of antibodies molecules in solution is critical to their development as therapeutics. For 19 different monoclonal antibody (mAb) solutions, we measured the viscosities, the second virial coefficients, the Kirkwood-Buff integrals, and the cluster distributions of the antibody molecules as functions of protein concentration. Solutions were modeled using the statistical-physics Wertheim liquid-solution theory, representing antibodies as Y-shaped molecular structures of seven beads each. We found that high-viscosity solutions result from more antibody molecules per cluster. Multi-body properties such as viscosity are well predicted experimentally by the 2-body Kirkwood-Buff quantity, G₂₂, but not by the second virial coefficient, B₂₂, and well-predicted theoretically from the Wertheim protein–protein sticking energy. Weakly interacting antibodies are rate-limited by nucleation; strongly interacting ones by propagation. This approach gives a way to relate micro to macro properties of solutions of associating proteins.

KEYWORDS:

• Aggregation
• viscosity
• G22
• modeling
• thermodynamic perturbation theory

Acknowledgments

S.B., K.A.D., and B.H.-L. acknowledge the support from the National Institutes of Health (NIH) RM1 award “Solvation modeling for next-gen biomolecule simulations” (grant No. RM1GM135136).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supporting information

Supporting information consists of details on experimental procedures, additional theoretical background, additional figures of our detailed mAb analysis and also results of homology modeling.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19420862.2024.2339582

Additional information

Funding

The work was supported by the National Institutes of Health [RM1GM135136].