LIGAND EFFICIENCY IN AXIAL AND RADIAL FLOW IMMUNOAFFINITY CHROMATOGRAPHY OF FACTOR-IX

Radial flow (RF) columns are attractive for process chromatography pri marily because larger throughputs and lower pressure drops are achieva ble in such columns. Large scale immunoaffinity processes using soft r esins can benefit most from this configuration. In this study, we comp ared immobilized ligand efficiency in axial flow (AF) and RF columns u sing monoclonal antibody against factor IX as the immobilized ligand a nd a coagulation factor IX complex as the source material. We examined the effects of flow-rate, total protein loading, feed antigen concent ration and direction of flow (centrifugal or centripetal for RF, and d ownward or upward for AF) on immobilized antibody capacity (measured a s mg antigen bound per mg antibody). Our results corroborate earlier w ork, and suggest that none of the factors, in the ranges examined, sig nificantly altered the efficiency of the monoclonal antibody (MAb) in binding factor IX. We also investigated the efficiency of the immobili zed antibody upon reuse and found that, over twenty cycles, there was no significant decrease in antibody efficiency. Our results demonstrat ed that efficiencies obtainable in AF columns can be achieved in RF co lumns with the same bed thickness, suggesting that radial dispersion, mass transfer and intraparticular diffusion may not have a significant influence on immunoaffinity chromatography efficiency in RF and AF co lumns.