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On the Optimal Ratio of Heavy to Light Chain Genes for Efficient Recombinant Antibody Production by CHO Cells
Author(s) -
Schlatter Stefan,
Stansfield Scott H.,
Dinnis Diane M.,
Racher Andrew J.,
Birch John R.,
James David C.
Publication year - 2008
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp049780w
Subject(s) - chinese hamster ovary cell , recombinant dna , monoclonal antibody , transfection , microbiology and biotechnology , gene , immunoglobulin light chain , plasmid , titer , chemistry , mutant , gene expression , biology , cell culture , antibody , biochemistry , genetics
Abstract Monoclonal antibodies (Mab) are heterotetramers consisting of an equimolar ratio of heavy chain (HC) and light chain (LC) polypeptides. Accordingly, most recombinant Mab expression systems utilize an equimolar ratio of heavy chain ( hc ) to light chain ( lc ) genes encoded on either one or two plasmids. However, there is no evidence to suggest that this gene ratio is optimal for stable or transient production of recombinant Mab. In this study we have determined the optimal ratio of hc : lc genes for production of a recombinant IgG 4 Mab, cB72.3, by Chinese hamster ovary (CHO) cells using both empirical and mathematical modeling approaches. Polyethyleneimine‐mediated transient expression of cB72.3 at varying ratios of hc : lc genes encoded on separate plasmids yielded an optimal Mab titer at a hc : lc gene ratio of 3:2; a conclusion confirmed by separate mathematical modeling of the Mab folding and assembly process using transient expression data. On the basis of this information, we hypothesized that utilization of hc genes at low hc : lc gene ratios is more efficient. To confirm this, cB72.3 Mab was transiently produced by CHO cells at constant hc and varying lc gene dose. Under these conditions, Mab yield was increased with a concomitant increase in lc gene dose. To determine if the above findings also apply to stably transfected CHO cells producing recombinant Mab, we compared the intra‐ and extracellular ratios of HC and LC polypeptides for three GS‐CHO cells lines transfected with a 1:1 ratio of hc : lc genes and selected for stable expression of the same recombinant Mab, cB72.3. Intra‐ and extracellular HC:LC polypeptide ratios ranged from 1:2 to 1:5, less than that observed on transient expression of the same Mab in parental CHO cells using the same vector. In conclusion, our data suggest that the optimal ratio of hc : lc genes used for transient and stable expression of Mab differ. In the case of the latter, we infer that optimal Mab production by stably transfected cells represents a compromise between HC abundance limiting productivity and the requirement for excess LC to render Mab folding and assembly more efficient.