Production of a Biologically Active Chimeric Mouse/Human Monoclonal Antibody in Insect Cells

Murine K20 (m-K20) monoclonal antibody (MAb) has an immunosuppressive effect by inhibiting human T-cell proliferation after binding to the s1-subunit of human integrins (CD29). In order to express a chimeric mouse/human form of K20 with an insect cells/baculovirus system, sequences encoding the variable regions of mu-K20 have been cloned and inserted into plasmid cassettes. Each cassette contains a baculovirus strong late promoter, a sequence encoding an immunoglobulin signal peptide and a sequence encoding a human constant region (respectively κ and γl). Subsequent transfer by homologous recombination into the baculovirus genome was performed to construct a recombinant virus for the co-expression of the light and heavy chain sequences of the MAb. Insect cells infected with this virus co-produce both chimeric K20 (Chi-K20) light (L) and heavy (H) chains which are assembled and secreted into the culture medium. ch-K20 was produced in a 10 liter stirred bioreactor, and purified by affinity chromatography. In vitro comparative assays showed that Chi-K20 and parental mu -K20 are indistinguishable by means of binding to CD29, cell specific targeting and inhibition of T-cell proliferation.