Objective To test whether the diphtheria toxin A (DT-A) chain coding sequence linked to murine immunoglobulin κ-light chain (Ig?κ) promoter and enhancer have selective cytocidal effects on Ig?κ producing cells. Methods The diphtheria toxin A gene or β-galactosidase (β-gal) gene were linked to a murine Ig?κ promoter and enhancer to construct pcDNA3Ig?κDTA or pcDNA3Ig?κLacZ plasmids. These plasmids were transfected into Ig?κ producing or non-producing cells by the liposome-coated DNA method. Expression of β-gal activity and effects on cell growth of transfected cells were assessed.Results The β-gal gene, under the control of cytomegalovirus (CMV) promoter, can express in all cell lines. Expression of β-gal under the control of the Ig?κ promoter was detected only in the Ig?κ producing cell line, CA46. Expression of β-gal was greatly suppressed when cotransfected with pcDNA3Ig?κDTA in CA46 cells. Cell growth of CA46 cells transfected with pcDNA3Ig?κDTA plasmid was significantly inhibited compared with CA46 cells transfected with pcDNA3Ig?κLacZ.Conclusion Selective killing of Ig?κ producing cells can be attained by introducing the diphtheria toxin A gene under the control of Ig?κ promoter and enhancer.
