Protein A affinity chromatography is the industry standard for capture of monoclonal antibodies in the downstream purification process. The Protein A step is a straightforward unit operation where the monoclonal antibody (MAb) is captured at near neutral pH and eluted using acidic pH. It is highly generic - most of the operating parameters can be predefined and identical for a number of different MAbs. However, some of the parameters, such as elution conditions, can benefit from further optimization for each individual MAb.
Antibody aggregation during cell-culture and/or in the downstream processing, particularly during the low pH elution from the Protein A column and subsequent low pH virus inactivation, can be a challenge. Monoclonal antibodies susceptible to low pH and prone to aggregation will profit from optimizing the elution step for lowest possible aggregation and high monomer recovery. Additives, such as arginine, in the elution buffer, can increase the pH where elution of the MAb occurs, and thereby preventing aggregation.