Intelligent Purification of Monoclonal Antibodies

Affinity chromatography has the advantage of purifying a species of protein quite specifically. For antibodies, the affinity ligand most commonly employed is Protein A which will bind to virtually all IgG antibodies as well as some IgM antibodies [1]. A number of potential disadvantages of Protein A chromatography have tended to inhibit its use. The expense of the Protein A ligand can be difficult to justify without adequate knowledge of the reusability of the matrix. However, Protein A column lifetimes in excess of 100 cycles have now been recorded [2]. Some IgG subclasseshave been difficult to purify on Protein A. However, the use of high salt buffers and alterations to the matrix chemistry which promote binding of the antibody to Protein A has overcome this problem resulting in a method that can now purify most classes of antibodies.