Use of Tunicamycin to Prepare Carbohydrate-Deficient Human Immune Interferon

This chapter describes the use of tunicamycin in the preparation of carbohydrate-deficient human type II interferon. The lack of affinity of the non-glycosylated interferon for concanavalin A-agarose is reported. Human type II interferon is prepared by stimulating whole leukocyte cultures with phytohemagglutinin (PHA) according to established procedures. The effect of tunicamycin on the biosynthesis of human type II interferon is shown. Leukocyte cultures that are incubated with no additives or with tunicamycin alone produced no detectable interferon. Type II interferon produced in the presence of tunicamycin (2 μg/ml) did not bind to Con A-Sepharose indicating that neither carbohydrate recognition nor hydrophobic interactions took place, Type II interferon is produced also in the presence of tunicamycin at a lower concentration (0.05 μg/ml) and is chromatographed on Con A-Sepharose according to the same protocol. Thus it appears that inhibition of glycosylation of human type II interferon not only abolishes its ability to bind to an immobilized lectin, but also alters its conformation to an extent that its hydrophobic binding sites are no longer available or accessible.