KINETIC-ANALYSIS OF HYBRIDOMA GROWTH AND MONOCLONAL-ANTIBODY PRODUCTION IN SEMICONTINUOUS CULTURE

Hybridoma I.13.17 was grown in semicontinuous culture in an attempt to investigate the steady-state concentrations of key components of monoclonal antibody (MAb) synthesis (e.g., intracellular MAb, IgG messenger RNAs) at different dilution rates between 0.008 and 0.055 h-1. There was a general trend of increasing steady-state levels of total cytoplasmic RNA, total cell-associated MAb or cytoplasmic MAb, DNA synthesis rate, cellular metabolic activity, heavy (H-) and light (L-) chain IgG mRNAs with the increase in dilution rates. Increase in the half-lives of H- and L-chain mRNAs with increase in dilution rates may be sufficient to account for their increasing levels found under the same conditions. The specific growth rate was profoundly affected by the dilution rate, particularly near the lower end of the dilution rate range. Linear relationships were observed between the steady-state amounts of total cell-associated MAb and the relative levels of H- and L-chain mRNAs. Material balances on intracellular MAb demonstrated an increasing percentage of antibody not released into the growth medium (e.g., stored within the cell or anchored to the cell membrane) with increasing dilution rate. The MAb production rate per cell decreased significantly with the increase in dilution rates. No correlation was found between the relative levels of H- or L-chain mRNAs and the specific MAb production rate. Possible implications of rate-limiting steps in MAb synthesis and secretion are discussed.