A kinetic analysis of hybridoma growth and metabolism in batch and continuous suspension culture: Effect of nutrient concentration, dilution rate, and pH (Reprinted from Biotechnology and Bioengineering, vol 32, pg 947-965, 1988)

Hybridomas are finding increased use for the production of a wide variety o f monoclonal antibodies. Understanding the roles of physiological and envir onmental factors on the growth and metabolism of mammalian cells is a prere quisite for the development of rational scale-up procedures. An SP2/0-deriv ed mouse hybridoma has been employed in the present work as a model system for hybridoma suspension culture. In preliminary shake flask studies to det ermine the effect of glucose and glutamine, it was found that the specific growth rate, the glucose and glutamine metabolic quotients, and the cumulat ive specific antibody production rate were independent of glucose concentra tion over the range commonly employed in cell cultures. Only the specific r ate of glutamine uptake was found to depend on glutamine concentration. The cells were grown in continuous culture at constant pH and oxygen concentra tion at a variety of dilution rates. Specific substrate consumption rates a nd product formation rates were determined from the steady state concentrat ions. The specific glucose uptake rate deviated from the maintenance energy model(1) at low specific growth rates, probably due to changes in the meta bolic pathways of the cells. Antibody production was not growth-associated; and higher specific antibody production rates were obtained at lower speci fic growth rates. The effect of pH on the metabolic quotients was also dete rmined. An optimum in viable cell concentration was obtained between pH 7.1 and 7.4. The viable cell number and viability decreased dramatically at pH 6.8. At pH 7.7 the viable cell concentration initially decreased, but then recovered to values typical of pH 7.1-7.4. Higher specific nutrient consum ption rates were found at the extreme pH values; however, glucose consumpti on was inhibited at low pH. The pH history also influenced the behavior at a given pH. Higher antibody metabolic quotients were obtained at the extrem e pH values. Together with the effect of specific growth rate, this suggest s higher antibody production under environmental or nutritional stress.