An IgA producing hybridoma cell line has been grown in various bioreactor systems, in serum-contg. and serum-free media. Bioreactors and media have been compared on the basis of product quantity (total IgA) and quality (activity, monomer/dimer/polymer ratios). IgA was produced in vitro with an activity similar to ascites fluid. The serum-free media was found to be better for such purposes. Prodn. in hollow fiber reactors resulted in high concns. of product, but with a lower activity fraction, possibly due to the formation of aggregates. [on SciFinder (R)]