PHYSIOLOGICAL STUDIES OF HYBRIDOMA CULTURES AND MONOCLONAL ANTIBODY PRODUCTION

Abstract

In a preliminary batch of 6BB hybridoma cells, the specific glucose consumption rate (Qg), specific glutamine consumption rate (Qgln) and specific antibody production rate (Qab) were found to be in a linear relationship with the specific growth rate (µ), but increased exponentially when µ > 1 hr-1 . Growth yield from D-glucose (Yx/c) and L-glutamine (Yx/n) were found to be 1.12 x 108 cells mmol-1 glucose and 1.31 x 109 cells mmol-1 glutamine respectively. The maximum initial specific growth rate (µi) was found at 4mM glutamine and 11mM glucose for 6BB hybridomas. Stoichiometric limitations of substrate in the culture medium were found at concentrations below 11mM glucose and up to 2mM glutamine. Conventionally, Qab is expressed as a function of dilution rate (D) or specific growth rate (µ). The present chemostat results show that there is an indirect relationship between Qab and µ. Unstructured kinetic models have been developed to explain the dynamics of hybridoma growth and the production of mAb in suspension cultures. The models partitioned glucose and/or glutamine into fractions for cell growth and antibody production. The steady state data exhibited excellent agreement with the proposed models. The data further suggested that growth-limiting substrate is first channeled to cell growth, and only when a minimum concentration of the substrate is conserved inside the cells that it is channelled to antibody production. Qgln of glucose-limited cultures and Qg of glutamine-limited cultures seem to be associated with the uptake rate of the growth limiting substrate, although the concentrations of this non-growth limiting substrates were saturated in the culture media that strongly suggested that the uptake of glucose and glutamine are tightly regulated. According to Linardos et al. ( 1991) the uptake rate or nutrients in a hybridoma culture is a function or the environmental stress. The death of 6BB hybridomas was found neither cause by lactate nor ammonium. Using a non-growth linked modelling framework, the phenomenon of death in 6BB is suggested to be caused by a nongrowth linked product.