Effect of feed rate on growth rate and antibody production in the fed-batch culture of murine hybridoma cells

Batch and fed-batch cultures of a murine hybridoma cell line (AFP-27) were performed in a stirred tank reactor to estimate the effect of feed rate on growth rate, macromolecular metabolism and antibody production. Macromolecu lar composition was found to change dynamically during batch culture of hyb ridoma cells possibly due to active production of DNA, RNA and protein duri ng the exponential phase. Antibody synthesis is expected to compete with th e production of cellular proteins from the amino acid pool. Therefore, it i s necessary to examine the relationship between cell growth in terms of cel lular macromolecules and antibody production. In this study, we searched fo r an optimum feeding strategy by changing the target specific growth rate i n fed-batch culture to give higher antibody productivity while examining th e macromolecular composition. Concentrated glucose (60 mM) and glutamine (2 0 mM) in DR medium (1:1 mixture of DMEM and RPMI) with additional amino aci ds were fed continuously to the culture and the feed rate was updated after every sampling to ensure exponential feeding (or approximately constant sp ecific growth rate). Specific antibody production rate was found to be sign ificantly increased in the fed-batch cultures at the near-zero specific gro wth rate in which the productions of cellular DNA, RNA, protein and polysac charide were strictly limited by slow feeding of glucose, glutamine and oth er nutrients. Possible implications of these results are discussed.