Anti- V.cholerae monoclonal IgA antibodies have been produced using a hybridoma cell line (Zac3) grown in RPMI medium contg. 10% Fetal calf serum (FCS) and a completely defined protein- free medium. The latter has been optimized with respect to amino acid, pluronic, glucose and glutamine content to give batch growth, total IgA concn., IgA productivity and dimeric IgA fraction which is even higher than that obtained during growth on the complex medium. The hybridoma has been grown in batch and continuous modes in a range of bioreactor configurations and the quantity and quality of the IgA produced detd. The results show that high cell d. systems (hollow fiber reactors) produce the highest concns. and productivities. However, the high concn. can result in the formation of high levels of polymeric forms which creates difficulties for the downstream processing. The bioreactor configuration had an important effect on IgA productivity, ratio of mono-, di- and polymeric forms as well as antigen binding activity. [on SciFinder (R)]