Detection of novel carbohydrate binding activity of interleukin-1

Abstract

Tamm-Horsfall glycoprotein (THGP) and the oligosaccharide fraction liberated from THGP by hydrazinolysis inhibited tetanus toxoid-induced T cell proliferation. Intact THGP showed approximately 100-fold more inhibitory activity than the free oligosaccharides. After fractionating the oligosaccharides by anion-exchange column chromatography, the inhibitory activity could be detected in a sialidase-resistant acidic oligosaccharide fraction (fraction AR). The inhibitory activity of fraction AR was not observed when the fraction was added to the T cell culture medium 24 h after the addition of tetanus toxoid. Increased concentration of interleukin (IL) 1β and decreased concentration of IL-2 were observed in the T cell culture medium after the addition of fraction AR. The oligosaccharides in fraction AR also inhibited the growth of an IL-1-dependent cell line, D10-G4. These results strongly suggested that the oligosaccharides in fraction AR bind to IL-1β and suppress its cytokine activity. IL-1β actually bound to the fraction AR immobilized on an amino-bonded thin layer plate. Fractionation of the oligosaccharides indicated that only oligosaccharides containing an N- acetylgalactosamine residue and a sulfate residue bound specifically to IL- 1β. Removal of either the sulfate residue or the N-acetylgalactosamine residue from the oligosaccharides abolished both the proliferation- inhibition and IL-1β binding activities. Since IL-1β did not bind to thyroid-stimulating hormone, which has the sulfate group at C-4 of the N- acetylgalactosamine residue in its N-linked sugar chains, the binding of IL- 1β toward oligosaccharides in fraction AR was considered to be highly specific.