Na-butyrate increases the production and alpha 2,6-sialylation of recombinant interferon-gamma expressed by alpha 2,6-sialyltransferase engineered CHO cells

A non-human like glycosylation pattern in human recombinant glycoproteins e xpressed by animal cells may compromise their use as therapeutic drugs. In order to correct the CHO glycosylation machinery, a CHO cell line producing recombinant human interferon-gamma (IFN) was transformed to replace the en dogenous pseudogene with a functional copy of the enzyme alpha 2,6-sialyltr ansferase (alpha 2,6- ST). Both the parental and the modified CHO cell line were propagated in serum-free batch culture with or without 1 mM sodium bu tyrate. Although Na-butyrate inhibited cell growth, IFN concentration was i ncreased twofold. The IFN sialylation status was determined using linkage s pecific sialidases and HPLC. Under non-induced conditions, IFN expressed by alpha 2,6- engineered cells contained 68% of the total sialic acids in the alpha 2, 6- conformation and the overall molar ratio of sialic acids to IF N was 2.3. Sodium butyrate addition increased twofold the molar ratio of to tal sialic acids to IFN and 82% of total sialic acids on IFN were in the al pha 2,6-conformation. In contrast, no effect of the sodium butyrate was not iced on the sialylation of the IFN secreted by the alpha 2,6-ST deficient p arental cell line. This study deals for the first time with the effect of N a-butyrate on CHO cells engineered to produce human like sialylation.