THE EFFECT OF THE DILUTION RATE ON CHO CELL PHYSIOLOGY AND RECOMBINANT INTERFERON-GAMMA PRODUCTION IN GLUCOSE-LIMITED CHEMOSTAT CULTURE

The physiology of a recombinant Chinese hamster ovary cell line in glu cose-limited chemostat culture was studied over a range of dilution ra tes (D = 0.008 to 0.20 h-1). The specific growth rate (mu) deviated fr om D at low dilution rates due to an increased specific death rate. Ex trapolation of these data suggested a minimum specific growth rate of 0.011 h-1 (mu(max) = 0.025 h-1) The metabolism at each steady state wa s characterized by determining the metabolic quotients for glucose, la ctate, ammonia, amino acids, and interferon-gamma (IFN-gamma). The spe cific rate of glucose uptake increased linearly with mu and the satura tion constant for glucose (K(s)) was calculated to be 59.6 muM. There was a linear increase in the rate of lactate production with a higher yield of lactate from glucose at high growth rates. The decline in the rate of production of lactate, alanine, and serine at low growth rate was consistent with the limitation of the glycolytic pathway by gluco se. The specific rate of IFN-gamma production increased with mu in a m anner indicative of a growth-related product. Despite changes in the I FN-gamma production rate and cell physiology, the pattern of IFN-gamma glycosylation was similar at all except the lowest growth rates where there was increased production of nonglycosylated IFN-gamma. (C) 1993 John Wiley & Sons, Inc.