Recombinant human interleukins IL-1 alpha, IL-1 beta, IL-4, IL-6, and IL-7show different and specific calcium-independent carbohydrate-binding properties

A method was developed for the determination of putative lectin activities of cytokines, It involved the immunoblotting measurement of the quantity of these cytokines unbound to a series of different immobilized glycoconjugat es and displacement of the bound cytokines with oligosaccharides of known s tructures. This method allows demonstrating that the following interleukins specifically recognize different oligosaccharide structures in a calcium-i ndependent mechanism: interleukin lcr binds to the biantennary disialylated N-glycan completed with two Neu5Ac alpha2-3 residues; interleukin-1 beta t o a GM, sialylated glycolipid Neu5Ac alpha2-3Gal beta1-Cer having very long and unusual long-chain bases; interleukin-4 to the 1,7 intramolecular lact one of N-acetyl-neuraminic acid; interleukin-6 to compounds having N-linked and O-linked HNK-1-like epitopes; and interleukin-7 to the sialyl-Tn antig en. Because the glycan ligands are rare structures in human circulating cel ls, it is suggested that such activities could be essential for providing s pecific signaling systems to cells having both the receptors and the oligos accharide ligands of the interleukin at their cell surface.