Hybridomas with non-growth-associated antibody production are thought to exhibit enhanced specific monoclonal antibody productivity ($q_MAb$) when subjected to hyperosmotic stress. Two hybridoma cell lines exhibiting non-growth-associated antibody production, S3H5/γ2bA2 and DB9G8 hybridomas, are cultivated in a batch mode using hyperosmolar media resulting from sodium chloride addition. Their response to hyperosmotic stress regarding $q_MAb$ is quite different, though they show similar depression of cell growth in hyperosmolar media. The $q_MAb$ of S3H5/γ2bA2 cells in a hyperosmolar medium (396 mOsm/kg, 10% fetal bovine serum (FBS) is enhanced by approximately 180% when compared with that in a standard medium (283 mOsm/kg, 10% FBS), while $q_MAb$ of DB9G8 cells in the same hyperosmolar medium is enhanced by only 10%. Thus, the enhanced $$q_MAb$ ot hybridomas exhibiting non-growth-associated antibody production resulting from hyperosmotic stress is cell line-specific.
To test the feasibility of using hyperosmolar medium for improved antibody production in a long-term, repeated fed-batch culture, the influence of various culture conditions (serum concentration and cultivation method) on the hybridoma cells`` response to hyperosmotic stress resulting from sodium chloride addition was first investigated in a batch culture. The degree of cell growth depression resulting from hyperosmotic stress was dependent on serum concentrations and cultivation methods (static and agitated cultures). Depression of cell growth was most significant in agitated cultures with low serum concentration. However, regardless of serum concentrations and cultivation methods used, the hyperosmotic stress significantly increased specific antibody productivity ($q_MAb$). Increasing osmolality from 284 to 396 mOsm/kg enhanced the $q_MAb$ in agitated cultures with 1% serum by approximately 124% while the similar osmotic stress enhanced the $q_MAb$ in static cultures with 10% serum...