Glycosylation of human leukocyte interferon: Effects of tunicamycin

Abstract

Summary Antiviral activity of interferon secreted by human leukocytes into the culture fluid in the presence of tunicamycin (1–2 µg/ml) was significantly decreased, by 50–60 percent, in comparison to that produced in the absence of the antibiotic. No loss in antiviral activity occurred when tunicamycin was added to already harvested interferon preparations. Some physico-chemical and biological properties of human leukocyte interferon synthesized in the presence of tunicamycin (HL-IF^T) were apparently altered by comparison with those of control preparations of human leukocyte interferon (HL-IF): HF-IF^T had only one molecular weight component of 16,000 daltons in contrast to the two components of HL-IF of 16,000 and 21,000 daltons. HL-IF^T also had a higher apparent hydrophobicity and was less efficiently neutralized by an antibody raised against HL-IF. However, some other properties remained unchanged: isoelectric point, pI about 6; affinity for immobilized polyriboinosinic acid and a spectrum of cross-species antiviral activity. These data support the notion that the major component of HL-IF (70 percent, 16,000 daltons) is apparently nonglycosylated whereas the minor component (30 percent, 21,000 daltons) is glycosylated via saccharide-lipid intermediates.