Cloning and expression of a chimeric antibody directed against the human transferrin receptor

The cloning, construction and expression of chimeric Ig genes, encoding a mAb directed against the human transferrin receptor, is described. From a mouse hybridoma cell line, secreting an antitransferrin receptor antibody, mRNA was prepared and converted into cDNA using Ig-specific oligonucleotides. H and L chain encoding cDNA fragments were isolated and sequenced. Chimeric genes were constructed by linking the murine V region cDNA fragments to human C region exons. After sequential transfection of nonproducing mouse hybridoma cells with the expression vectors containing the chimeric H and L chain genes, antibody secreting transfectomas were obtained. ELISA and immunoblot analysis clearly demonstrate the secretion of human kappa- and gamma-1 chain. Flow microfluorimetry analysis of the chimeric antibody shows that the Ag-binding capacity has been retained. The chimeric antibody most likely will be less immunogenic then the original mouse antibody when used in human cancer therapy.