Applications of ion-exchange chromatography for the purification of antibodies

Antibodies are Y-shaped protein molecules generated by the immune system that can bind specific target molecules and initiate subsequent biological effects. The immunoglobin G (IgG) is the most widely utilized format in protein therapeutics. In industry, antibodies are often expressed by recombinant DNA technology in Chinese Hamster Ovary (CHO) cells. Purification of antibodies usually includes three steps, of which two polishing steps are ion-exchange chromatography. Cation-exchange chromatography (in bind-and-elution mode) is used for the removal of product-related impurities, while anion-exchange chromatography (in flow-through mode) is used for the removal of process-related impurities. Process development of ion-exchange chromatography includes resin screening, elution program development, loading parameters optimization, and determination of operating space. Scale-up and scale-down is achieved by keeping bed height, linear flow rate, and load ratio constant while changing column diameter. As antibody-derived therapeutics are getting more and more diversified, process developers should aim for a deep understanding of the target protein and impurity profile to ensure the success rate of process development.