Real-time isoform analysis by two-dimensional chromatography of a monoclonal antibody during bioreactor fermentations

A humanized monoclonal antibody specific for L-selectin exhibits two distinct isoforms that are distinguishable by a charged group modification on one of the antibody light chains. The added charge allows baseline separation of the isoforms by anion-exchange chromatography. Since this modification most likely results from specific enzymatic activity within the Golgi complex, it is possible that fermentation conditions may affect the relative amounts of the isoforms produced. Herein is described a two-dimensional chromatographic method for quantifying the relative amounts of the isoforms from fermentation broths, in real time.