Evaluation of production of recombinant human interleukin-2 in fluidized bed bioreactor

The production of recombinant human interleukin-2 in a fluidized bed bioreactor containing porous glass carriers is described. Cultivations were carried out with different medium formulations over 80 days. Maximal cell densities and product yield could be maintained even when protein free medium was perfused, with less than 10% cell washout. Due to this effective immobilization of the cells in the reactor, continuous operation was easy to perform. Final cell densities on the order of 3.8 x 10(8) mL(-1) intrasphere volume were reached while the interleukin-2 production rate was 0.75 mg L(-1) d(-1). The production rate showed a maximum of a 1.9 fold decrease compared with a homogeneous stirred bubble-free aerated system. This result was in contrast to that achieved with hybridoma cell lines, where better performance was obtained with the fluidized bed bioreactor. The situation may reflect the problems caused by the dense cell culture with adherent cells, as previously shown in a hollow-fiber bioreactor with the same cell line.