we try to produce antibodies in the new Expi293 suspension cells (Life Technologies) by transient transfection with two pFUSE expression vectors for light and heavy chain. The cells suffer from high cell death with only ca. 65% viability 3 days after addition of DNA:ExpiFectamine complex. There are also dead cells by only adding the ExpiFectamine. Is there anyone else with comparable observations? Any idea for optimizing the experiment to reduce cell death?