[Affinity chromatography for extracorporeal purification or for separation of molecules for biological use: technical...

Affinity and/or immunoaffinity chromatography is one of the less commonly method used for large scale separation purposes. As this technic is greatly selective and gives high yields, it allows in vivo removal, in an extracorporeal circulation, of harmful substances in patient plasma as well as purification of molecules for biological and therapeutic uses. Large development with increased safety of such a method is dependent on some economic, technical and legal requirements. Particular attention must be drawn to the following points. Possibility of multiple uses of affinity supports contributes to lowering the cost of the method. Desorption agents should be chosen according to the best compromise between total desorption and preservation of adsorption capacity over runs. It is likewise essential to store affinity supports in conditions allowing prevention from contamination without loss of adsorption capacity. In developing and optimizing an affinity chromatography procedure, it is important to minimize the amount of ligand released from the affinity support. Besides economic and technical aspects, it is necessary to take into account legal requirements, particularly those related to the preparation of the ligand especially if it is monoclonal or polyclonal antibodies. An important consideration for the therapeutic use of antibodies (either in the preparation of biological products or in an extracorporeal circulation procedure) is the possible presence of viruses and/or potentially oncogenic macromolecules. Source material should be shown to be free of viruses, the cell banks (for monoclonal antibodies) and the production of antibodies must be closely controlled, viral inactivation of antibodies should be performed and the inactivation process should be shown to be effective.