This paper describes the prodn. of IgA antibodies in a range of bioreactor configurations using FCS-contg. RPMI 1640 medium. Under std. batch STR conditions, a max. viable cell and IgA concns. of 9.5*105 cell mL-1 and 47 mg l-1 were obtained. Under fed-batch conditions, these values were increased by a factor of 60% and 155%, resp. IgA concn. was increased by a factor of more than 10-fold in a HFR. The reason for the low yields in suspension cultures is probably due to limitations of essential nutrients, such as the balance of amino acids. A defined serum- and protein-free medium has been developed to explore this in more detail. [on SciFinder (R)]