Proteolytic Potential during Batch Cultivation in Serum Free Media of an IFN-γ Producing CHO Cell Line

Abstract

CHO-320 cells have been genetically modified to produce human gamma interferon (hu IFN-γ). IFN-γ is secreted as monomers, dimers, and multimers complexes. During batch culture, IFN-γ is less degraded when CHO cells are cultivated in media supplemented with Quest rice peptones than with CWBI rice peptones. Zymogs. on gelatin were conducted to detect extracellular peptidase. A 90-93 kDa pro-form of a peptidase was secreted in the extracellular medium which shows gelatinase activity. This 90-93 kDa metallopeptidase was activated by p-aminophenylmercuric acetate, a typical activator of matrix metallopeptidase (MMP). As mol. wt. and general characteristics correspond to MMP-9, western blots were performed using polyclonal anti-mouse MMP-9. CHO-320 cells secrete constitutively MMP-9 (gelatinase B). The Chinese hamster MMP-9 was secreted as the inactive pro-form of the peptidase. The IFN-γ produced in CHO-320 cells undergoes proteolysis depending on the formulation of the medium. [on SciFinder(R)]