An Efficient Transient Expression System for Enhancing the Generation of Monoclonal Antibodies in 293 Suspension Cells.
BACKGROUND
Recombinant monoclonal antibodies (mAbs) are useful in research, diagnosis, and therapy. The increased demands of recombinant mAbs require efficient production systems. A variety of expression vectors have been developed for stable or transient production of mAbs in mammalian cells. Although a few commercial expression systems of mAbs can be listed, the high expense often impedes academic research.


METHODS
In this study, we described the development of a transient mammalian system based on a bicistronic vector, which contained an internal ribosome entry site (IRES) and enhancer elements to express the IgG1 light chain (LC) and heavy chain (HC) in one transcript. Optimization of all components of the expression system, including gene transfer methods and regulatory elements, yielded maximal expression levels in serum-free 293 suspension cells (Freestyle 293-F).


RESULTS
This method enabled consistent production of the anti-programmed cell death protein 1 (PD-1) mAb up to 300 mg/L in less than one week under transiently transfected conditions. Furthermore, purified anti-PD-1 IgGs showed specific affinity to the target antigen human PD-1 and PHA-stimulated human T cells.


CONCLUSIONS
The simplicity of the procedure made it suitable for the fast and high-yield production of IgG antibodies in small scales, which expedited the screening of a large number of recombinant candidates.
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedical Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei. China.
Guoquan
G
Zhang
Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong. China.
Jie
J
Liu
Medical Center of Stomatology, Wuhan University, Wuhan, Hubei. China.
Wanting
W
Fan
Medical Center of Stomatology, Wuhan University, Wuhan, Hubei. China.
Qianyi
Q
Chen
School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei. China.
Bin
B
Shi
D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000235:genetics; D002452:Cell Count; D003001:Cloning, Molecular; D016895:Culture Media, Serum-Free; D015870:Gene Expression; D005822:Genetic Vectors; D057809:HEK293 Cells; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis* / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis* / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000096:biosynthesis* / Q000235:genetics; D061026:Programmed Cell Death 1 Receptor / Q000037:antagonists & inhibitors / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D014162:Transfection
D000911:Antibodies, Monoclonal; D016895:Culture Media, Serum-Free; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor; D011994:Recombinant Proteins
293 suspension cell; Antibody; PD-1; human β-globin intron; mammalian expression; transient expression