Novel peptoid-based adsorbents for purifying IgM and IgG from polyclonal and recombinant sources

Polyclonal immunoglobulin therapeutics comprising dosed IgG and IgM combinations are powerful tools in fighting cancer and severe infections. The inability of protein ligands to produce polyclonal IgG- and IgM-enriched formulations and recover monoclonal IgM calls for novel ligands with superior biorecognition activity. In this study, a peptoid ligand discovered by our group, and integrated into affinity adsorbents LigaTrap Technologies' "Human IgG" and "Human IgM", were utilized to purify IgG and IgM from complex fluids. IgG purification from human serum using LigaTrap IgG afforded 94.6% purity and 62.9% yield, on par with Protein A/G resins. When challenged with CHO and HEK cell culture harvests with low IgG titer (<1 mg/mL), LigaTrap IgG returned values of yield and purity well above 60% and 90%. LigaTrap IgM was evaluated for purifying IgM in comparison with commercial adsorbents, and afforded a product purity of 93% from a CHO harvest (IgM titer of 1 mg/mL) and 75.1% yield from a HEK harvest (0.5 mg/mL). LigaTrap-M provided IgM enrichment up to 11-fold higher than HiTrap resin. The peptoid adsorbents separated IgG-depleted human serum into IgM- and IgA-enriched fractions. These results demonstrate the potential of the peptoid ligand for manufacturing polyclonal Ig formulations and monoclonal IgM therapeutics.