EXTENSION OF SP2 0 HYBRIDOMA CELL VIABILITY THROUGH INTERLEUKIN-6 SUPPLEMENTATION/

Sp2/0 hybridoma cells die principally by apoptosis in batch culture. W e have found that cultures of the Sp2/0 hybridoma exhibit increased vi ability in response to interleukin 6 (IL-6) supplementation relative t o control cultures during serum shiftdown experiments. When shifted fr om a medium containing 10% fetal bovine serum (FBS) to a medium with 1 % FBS, IL-6 supplemented cultures displayed viabilities and Viable cel l densities similar to control cultures containing 10% FBS. The degree of the survival response induced varied in accordance with the severi ty of the shiftdown, as cells resuspended in a high serum medium showe d little observable enhancement in viability. The extension in culture viability was not accompanied by an observable decrease in growth rel ative to control cultures, indicating that the effect was not a conseq uence of growth inhibition. These results suggest the existence of ser um components with behavior functionally similar to IL-6, with respect to enhancing cell survival, and that under certain experimental condi tions IL-6 serves as a survival factor. in contrast to the extended vi ability displayed by cultures supplemented with IL-6, Sp2/0 cultures t ransfected with IL-6 cDNA expression vectors displayed a growth inhibi tory response relative to control cultures. This inhibitory response w as characterized by an extended lag phase following inoculation, and a decrease in batch culture cell yield. The depression in cell yield va ried with serum concentration, with the largest depression occurring a t high serum concentrations. We conclude that interactions between com ponents in serum, presumably growth factors, and cytokines play an imp ortant role in altering the behavior of industrially relevant cell lin es in culture. (C) 1997 John Wiley & Sons, Inc.