Influence of the KDEL signal, DMSO and mannitol on the production of the recombinant antibody 14D9 by long-term Nicotiana tabacum cell suspension culture

We have established two transgenic cell suspension culture lines of Nicotiana tabacum that express the catalytic antibody 14D9 as a secretory product (sec-Ab) or as a KDEL-tagged product in the endoplasmic reticulum (Ab-KDEL), respectively. After 3 years of culture, the performance improved to a production level of 0.15 +/- 0.03 mu g ml(-1) on the seventh day of culture for the sec-Ab line and 0.48 +/- 0.05 mu g ml(-1) on the third day for Ab-KDEL line. Analysis of the effect of osmotic stress using mannitol (90 g l(-1)) as an osmolite revealed that there was a 12-fold increase in antibody yield (1.96 +/- 0.20 mu g ml(-1)) on the seventh day of culture in line sec-Ab and a fivefold increase (2.31 +/- 0.18 mu g ml(-1)) on the seventh day for line Ab-KDEL. The concentration of the antibody in the culture medium was not significant. Dimethyl sulfoxide used as a permeabilizing agent was not effective in increasing 14D9 yield, but it did cause distinctive cell damage at all concentrations tested.