AB2-143.2 cells exhibit non-growth-associated antibody production (constant specific antibody production rate (q(Ab)) throughout batch culture), while IND1 cells exhibit growth-associated production (decrease in q(Ab) during stationary phase). AB2-143.2 cells increase q(Ab) following abrupt batch osmotic stress. Enhanced antibody production in IND1 cells after batch osmotic shock is evidenced as maintenance:of the higher exponential phase q(Ab) into the stationary phase. AB2-143.2 cells also increase Q(Ab) in response to gradual osmotic stress in continuous culture. In contrast, IND1 cells decrease Q(Ab) during gradual osmotic stress. Although the two cell lines differ in antibody production, they have very similar intracellular antibody content profiles. Both show (1) constant antibody content during the exponential phase in control culture with a decrease as cells enter stationary phase; (2) maintenance of exponential-phase antibody content into the stationary phase after batch osmotic shock; and (3) no change in antibody content in response to gradual osmotic stress.