Hybridoma growth and productivity: effects of conditioned medium and of inoculum size

Apart from gas concentrations, temperature, and pH, generally only the init ial conditions can be manipulated in batch culture. Inoculum size and initi al conditioned medium concentration represent two important considerations for optimal batch production. Two hybridoma cell lines were used to assess the impact of these initial conditions on population growth and monoclonal antibody productivity in suspension batch culture. Varying initial cell con centration over the range of 1.0 X 10(5) cells mL(-1) to 3.0 X 10(5) cells mL(-1) did not affect maximum product titre or maximum volumetric cell-hour s attained. Initial percent of conditioned medium up to 40 percent strongly impacted on population growth and productivity, with initial levels of 30 to 40% conditioned medium reducing or eliminating lag phase and increasing average viable cell density. However, specific productivity and product tit re declined with increasing initial percent conditioned medium, even on a p er volume of fresh medium basis. Glutamine and glucose depletion or ammonia toxicity could cause depressed product titres when conditioned medium is u sed. Glutamine and glucose levels can easily be replenished in conditioned medium at minimal cost, and ammonia can be removed. Specific productivity w as higher during cyclic batch operating mode than during batch operating mo de. This may be because cyclic batch operating mode results in an incidenta l volume of conditioned medium at the beginning of each cycle. A two stage, cyclic-batch/batch operating mode can be employed to fully utilize medium and maximize product titre.