Stable production of recombinant human sperm immobilizing antibody using cDNA expression vectors

Sperm immobilizing antibodies present in sterile women may be one of the principal causes of immunological infertility. We already established cell lines that secrete recombinant human IgG sperm immobilizing antibody using class-switched (from IgM to IgG) genomic immunoglobulin genes. However, these transfectants produced a small quantity of antibody and required continuous use of a medium with selective reagents. We have now constructed cell lines that stably secrete the antibody in large quantities using immunoglobulin cDNAs and cDNA expression vectors.

The immunoglobulin heavy chain cDNA was cloned from transfectants that secrete the class-switched human IgG sperm immobilizing antibody. The light chain cDNA, which had already been cloned, and the heavy chain cDNA were inserted into the modified bovine papilloma virus-based cDNA expression vectors BCMGSNeo and BCMGSHyg, respectively. These constructs were sequentially transfected into a mouse myeloma cell line by electroporation.

The established transfectants produced recombinant antibody that retained human sperm immobilizing activity in nonselective medium for at least 30 days. Moreover, the production of the antibody was increased three times over that of the previous cell lines.

We have established an unique method that improves the production of sperm immobilizing antibody stably and in large quantities.