Long-term production of human monoclonal antibodies by five human-mouse heterohybridomas in a serum-free medium.

Four heterohybridomas (28K29, 27D57, ZLG40, and 29D38) secreting human monoclonal antibodies (MAbs) reactive with lung cancer cells and one heterohybridoma (28B49) secreting an isotype-matched MAb (IgM, lambda) were adapted and tested for long-term MAb production in serum-free medium. Three typical serum-free media were first evaluated for this purpose, based on the MAb productivity, cost, and ease of MAb purification with each, and Hybridoma-SFM, containing only insulin and transferrin as protein components, was selected as the most appropriate. In this medium, all five heterohybridomas continued to proliferate and secrete MAb throughout test periods of 144 to 200 days. Achievement of this long-term, stable production may be attributed at least in part to the effects of extensive prior subcloning and to the predominance of lambda-type light chains in the IgM antibodies produced by these heterohybridomas. The results of this study provide the basis for development of a process to produce large quantities of human MAbs, which may be useful for therapeutic or in vivo diagnostic purposes.