Purification of monoclonal antibodies from ascitic fluid using preparative electrophoresis

Abstract

Four monoclonal antibodies (including Ig subclasses, G1, G2a and G2b) were purified from murine ascitic fluid by a preparative electrophoresis system using a charge- and size-based strategy. Most of the smaller contaminating proteins were removed at pH 8.3 when the ascitic fluid was passed through a cartridge containing a separating membrane with a pore size of M r 100 000. After this single step, the immunoglobulin heavy and light chains were the only significant bands present when analysed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. A second step, involving electrophoresis at pH 6.4–7.5 depending on the antibody can be used to remove residual contaminants. For each of the antibodies tested, the recovery of activity at each step was over 80%. As this technology is directly scalable, purification of antibodies by the method described here could be considered a cost effective alternative to protein A chromatography.