INFLUENCE OF PRIMATONE RL SUPPLEMENTATION ON SIALYLATION OF RECOMBINANT HUMAN INTERFERON-GAMMA PRODUCED BY CHINESE-HAMSTER OVARY CELL-CULTURE USING SERUM-FREE MEDIA

Although serum-free media have been widely used in mammalian cell cult ure for therapeutic protein production, the effects of serum-substitut es on product quality have not been extensively examined. This study o bserved an adverse effect of Primatone RL, an animal tissue hydrolysat e commonly used as a serum-substitute to promote cell growth, on sialy lation of interferon-gamma (IFN-gamma) derived from Chinese hamster ov ary (CHO) cell culture in both batch and fed-batch modes. In batch cul tures, decreased sialylation was observed at each of the glycosylation sites (i.e., Asn(25) and Asn(97)) of IFN-gamma with the use of elevat ed concentrations of the peptone. Although poorest sialylation was obt ained with the use of a growth-inhibiting concentration of Primatone R L, diminished sialylation was observed at the optimal peptone concentr ation for cell growth and product yield. Since incubation of the produ ct in Primatone RL-supplemented acellular medium did not result in dec reased sialylation, the negative effect of Primatone RL could not be a ttributed to extracellular desialylation of IFN-gamma by components of the peptone. In the fed-batch mode, a culture utilizing a serum-free feeding medium supplemented with Primatone RL demonstrated poorer sial ylation than a similar culture not fed the peptone. The results of bot h the batch and fed-batch experiments indicate that the adverse effect of the peptone was not due solely to ammonia accumulation. (C) 1997 J ohn Wiley & Sons, Inc.