IgG-BSA separation and purification by internally staged ultrafiltration

Abstract

Purification of IgG from residual host cell proteins (HCPs) in post-Protein A chromatography is important since some HCPs bind with Protein A and elute with the monoclonal antibody (mAb); removal of HCPs from CHO cell lines is essential. To that end, an advanced separation and purification technique in biopharmaceutical manufacturing, namely, internally staged ultrafiltration (ISUF), is investigated here. Choosing BSA as a model for HCPs in post-protein A eluate, separation of a binary mixture of IgG and BSA containing 1.0 mg/ml IgG and 0.1 mg/ml BSA is successfully demonstrated here using a modified ISUF technique: two Omega 100 kDa membranes on top followed by one Omega 70 kDa membrane at the bottom. This modified configuration demonstrated exceptional performance with almost complete rejection, 99 % purity, and 99.5 % retention of IgG, along with 96.5 % recovery of BSA over 10 diavolumes. This modified membrane stacking resulted from strategic considerations of membrane stacking and careful selection of molecular weight cutoffs and materials, and performance analysis of different membranes and stacking configurations using rejection behaviors, purity levels, and recovery rates under varying diavolume and pressure differential. The approach adopted here enhances flexibility in membrane choices in ISUF and provides valuable insights for optimizing membrane-based biopharmaceutical separation techniques.