Ctla4-ig Expression, Modification And Tumor Immunotherapy Strategic Studies

CTLA4Ig is a soluble chimeric protein consisting of extracellular domain of human CTLA4Ig and a fragment (hinge,CH2, and CH3 domains) of the Fc of human IgG1. CTLA4Ig binds to B7 molecules on APCs and thereby blocks the B7 mediated co-stimulatory signal for T-cell activation and so may be used as immunosuppressant in organ transplantation. In this study. CTLA4Ig chimeric molecule was cloned into eukaryotic expression vector pCI-dhfr. Using lipofectine-mediated gene transfer technique, pCI-CTLA4Ig was transfected into CHO-dhfr-cell ,and the transfectants were selected with methotrexate (MTX) . Expression of the recombinant protein was assessed by RT-PCR, ELISA, cell immunofluorescence stain and Western-blot, and at last the recombinant protein purification was performed by protein A chromatography.