Transient production of the 3 cMAbs by 8 common mammalian host cellsa.

aThese cell lines were used to select a maximum producer by transient expression using the pIRES-H/L-DHFR vector system. These cells (∼106 cells/10 cm dish) were incubated for 72 h after cotransfection with complex mixtures of each pIRES-H (L)-DHFR DNAs (10 µg/dish) and LF-2000.bCulture supernatants of each cMAb were used to measure the cMAb levels by a modified human IgG1 ELISA. The assay detection limit of cMAb was 4 ng/ml. The values are the means ± standard deviations of 3 independent experiments.cSince the transformed IM-9 cell line has a machinery to produce human IgG/κ chain, the antibody levels detected in the assay system were from the majority of endogenous human IgG/κ, not cMAbs.dNT: Not tested.