[High efficiency expression of IL-4 using modified cDNA expression vector in mammalian cells].

In order to express eukaryotic gene in eukaryotic cells, a cDNA library was constructed and screened with synthesized probe of IL-4 cDNA. The obtained cDNA fragment 739 bp in length was inserted into pi H3M plasmid and expressed (8 x 10(3) IU/ml) in COS cells. A pdB-HhIL-4 expression plasmid was constructed using pdKCR and pdBPV-1 plasmid and transfected into mouse C127 cells by calcium phosphate coprecipitation. Transfected cells exhibited altered cell morphology, could be continuously cultured in DMEM essential medium and secreted IL-4 lymphokine into 1% FCS condition culture medium. High biological activity (2 x 10(4)/ml) from the culture supernatant was obtained by FACS analysis of Fc epsilon receptor expression on B cell surface.