Secretion analysis of intracellular “difficult-to-express” immunoglobulin G (IgG) in Chinese hamster ovary (CHO) cells

• Published in: Cytotechnology (Dordrecht) Vol. 71; no. 1; pp. 305 - 316
• Main Authors: Kaneyoshi, Kohei, Kuroda, Kouki, Uchiyama, Keiji, Onitsuka, Masayoshi, Yamano-Adachi, Noriko, Koga, Yuichi, Omasa, Takeshi
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-02-2019; Springer Nature B.V
• Subjects: Antibodies; Biochemistry; Biomedicine; Biotechnology; Chemistry; Chemistry and Materials Science; Cloning; Efficiency; Endoplasmic reticulum; Engineering; Golgi cells; Immunoglobulin G; Immunoglobulins; Infliximab; Light chains; Localization; Medical research; Microscopy; Monoclonal antibodies; Ovaries; Producer cells; Productivity; Proteins; Toxicity; Tumor necrosis factor-α; United States > US; Japan; Animal cell culture; Therapeutic antibody production; Difficult-to-express IgG; Protein secretion; Chinese hamster ovary cell
• ISSN: 0920-9069; 1573-0778
• DOI: 10.1007/s10616-018-0286-5

The Chinese hamster ovary (CHO) cell line is the most widely used host cell for therapeutic antibody production. Although its productivity has been improved by various strategies to satisfy the growing global demand, some difficult-to-express (DTE) antibodies remain at low secretion levels. To improve the production of various therapeutic antibodies, it is necessary to determine possible rate-limiting steps in DTE antibody secretion in comparison with other high IgG producers. Here, we analyzed the protein secretion process in CHO cells producing the DTE immunoglobulin G (IgG) infliximab. The results from chase assays using a translation inhibitor revealed that infliximab secretion could be nearly completed within 2 h, at which time the cells still retained about 40% of heavy chains and 65% of light chains. Using fluorescent microscopy, we observed that these IgG chains remained in the endoplasmic reticulum and Golgi apparatus. The cells inefficiently form fully assembled heterodimer IgG by making LC aggregates, which may be the most serious bottleneck in the production of DTE infliximab compared with other IgG high producers. Our study could contribute to establish the common strategy for constructing DTE high-producer cells on the basis of rate-limiting step analysis.