title: Non-immunospecific association of immunoglobulin G with chromatin during elution from protein A inflates host contamination, aggregate content, and antibody loss.
abstract: Monoclonal IgG at pH 3.5 expressed a tendency to self-associate and associate non-specifically with surfaces, including the surfaces of precipitated chromatin heteroaggregates. The tendency was elevated with protein A-eluted IgG still in elution buffer (100mM acetate, pH 3.5). Association of IgG with chromatin elements under protein A elution conditions amplified host protein contamination of the elution fraction about 15-fold, caused formation of aggregates that persisted after pH neutralization, and imposed an approximate 5% loss on IgG recovery. Neutralization released eluted IgG from its low pH associations with chromatin and caused heteroaggregate remnants to associate into large particles easily removed by microfiltration. Most effective host contaminant clearance was achieved by filtration after neutralization to pH 5.5. All chromatin-mediated liabilities were suspended by extraction of chromatin heteroaggregates in advance of protein A.
authors.affiliation: Bioprocessing Technology Institute, 20 Biopolis Way, Centros #06-01, Singapore 138668, Singapore. Electronic address: pete_gagnon@bti.a-star.edu.sg.
authors.forename: Pete
authors.initials: P
authors.lastname: Gagnon
authors.affiliation: Bioprocessing Technology Institute, 20 Biopolis Way, Centros #06-01, Singapore 138668, Singapore.
authors.forename: Rui
authors.initials: R
authors.lastname: Nian
authors.affiliation: Bioprocessing Technology Institute, 20 Biopolis Way, Centros #06-01, Singapore 138668, Singapore.
authors.forename: Yuansheng
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Bioprocessing Technology Institute, 20 Biopolis Way, Centros #06-01, Singapore 138668, Singapore.
authors.forename: Qiaohui
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Bioprocessing Technology Institute, 20 Biopolis Way, Centros #06-01, Singapore 138668, Singapore.
authors.forename: Chiew Ling
authors.initials: CL
authors.lastname: Lim
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry*; D002021:Buffers; D002843:Chromatin / Q000737:chemistry*; D002846:Chromatography, Affinity; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000737:chemistry*; D066329:Protein Aggregates; D013205:Staphylococcal Protein A / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D002021:Buffers; D002843:Chromatin; D007074:Immunoglobulin G; D066329:Protein Aggregates; D013205:Staphylococcal Protein A
keywords: Aggregation; Chromatin; Host contamination; IgG; Protein A; Recovery