Monitoring of the production of monoclonal antibodies by hybridomas. Part I: Long-term cultivation in hollow fibre bioreactors using serum-free medium.

The long-term cultivation of hybridoma cells in hollow fibre bioreactors using serum-free medium, was monitored with respect to quantitative and qualitative aspects of the produced mAbs, cell viability, LDH and proteolytic activity. During the culture periods of hybridoma cells producing mAb OT-1C and 3A, the mAb concentration showed a decreasing trend with a concomitant increase of IgG fragments. The major IgG fragments did not bind the antigen and the molecular weights were significantly different from the corresponding IgG heavy and light chains. In addition, a good correlation was found between cell lysis, the presence of acid protease(s) and IgG fragments. The physicochemical and immunochemical properties of the "intact" mAbs (such as molecular weights, IEF patterns and affinity) did not change significantly during the culture period.