Table 2. Transient production of the 3 cMAbs by 8 common mammalian host cells^a.

Cell line	Description	Concnb (ng/ml)
		CK1	CK2	CK3
CHO-K1	Chinese hamster ovarian cell - Used with transient expression and glutamine synthetase system	370±52	357±47	434±86
CHO-DG44	Chinese hamster ovarian cell - Used for DHFR coamplification to make stable clones for cMAbs	37±6	33±5	173±12
293T	Transformed human embryonic kidney cell with T antigen - Used for transient small-scale production	167±7	37±3	404±45
COS-7	Transformed African green monkey kidney cell -Used for transient small-scale production	226±10	196±8	441±72
BHK-21	Baby hamster kidney cell - Used for stable gene integration	35±7	38±6	177±13
Sp2/0-Ag14	Mouse myeloma cell - Used for obtaining hybridoma which produce MAbs as a fusion partner	<4	<4	<4
P3×36-Ag8.653	Mouse myeloma cell - Used for obtaining hybridoma which produce MAbs as a fusion partner	<4	<4	<4
IM-9c	EBV-transformed human B-lymphoblast cell – Derived from the blood of a patient with multiple myeloma	NTd	NT	424±57

^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.