Opalescence Arising from Network Assembly in Antibody Solution.

Opalescence of therapeutic antibody solutions is one of the concerns in drug formulation. However, the mechanistic insights into the opalescence of antibody solutions remain unclear. Here, we investigated the assembly states of antibody molecules as a function of antibody concentration. The solutions of bovine gamma globulin and human immunoglobulin G at around 100 mg/mL showed the formation of submicron-scale network assemblies. The network assembly resulted in the appearance of opalescence with a transparent blue color without the precipitates of antibodies. Furthermore, the addition of trehalose and arginine, previously known to act as protein stabilizers and protein aggregation suppressors, was able to suppress the opalescence arising from the network assembly. These results will provide an important information for evaluating and improving protein formulations.