Bioprocessing method is a critical factor for IgM oligomerization

Abstract Monoclonal immunoglobulins of subclass M pose great potential to fight diverse medical complications with high efficiency. We present a comparison of stable recombinant Chinese hamster ovary DG44 and K1 cell lines expressing IgM comprising κ-light chains and µ-heavy chains either with or without a joining chain molecule, yielding pentameric (5IgM) or hexameric IgM (6IgM) molecules, respectively. Both recombinant cell lines were bioprocessed via fed-batch and via semi-continuous perfusion methods. Production techniques were compared based on their viable cell concentrations, specific growth rates (µ), metabolite levels and their space–time yields. Recombinant cell lines were characterized regarding their intra- and extracellular expression levels and post-processing oligomerization states. Furthermore, a single-step anion exchange chromatography is showcased as a quick and efficient purification method for high concentration harvests, preserving critical pH and salt concentrations required for IgM stability. Daily replenishment of fresh medium and removal of toxic metabolites in the SP bioprocess contributed to enhanced oligomeric homogeneity of the product thereby allowing greater volumetric bioreactor productivity notably prominent for 6IgMs. Key points • Direct comparison of FB and SP methods for pentamer and hexamer IgM production • SP of CHO cells yields >500 mg 5IgM and >1000 mg 6IgM per liter per day • Choice of bioprocessing influences the homogeneity of IgM oligomerization