Role of monosaccharides in the interaction of two lymphocyte mediators with their target cells

The role of monosaccharides on the interaction of two lymphocyte mediators related to the human cell migration inhibition systems with their respective target cells has been investigated. Human MIF activity on blood monocytes was significantly reduced by several 5-methylpentose sugars indcluding L-fucose, L-rhamnose and 6 deoxy-D-glucose. Certain structurally unrelated monosaccharides such as D-galactose, methyl alpha-D-mannoside and N-acetyl-D-glucosamine had no effect on this system. Incubation of human monocytes with alpha-L-fucosidase, a glycosidase which cleaves terminal L-fucose moieties, reversibly prevented their response to MIF. These results indicate that alpha-L-fucosyl residues form an integral part of the receptor for MIF on human monocytes, and furthermore, this interaction may be somewhat nonspecific in that the 5-methylpentose configuration perse is recognized. In contrast, human LIF activity on PMN leukocytes was significantly reduced by N-acetyl-D-galactosamine, but not by 5-methylpentoses, D-glucose, N-acetyl-D-galactosamine, methyl alpha-Dmannoside or D-galactose. The latter finding suggests that a subterminal sugar may form part of the receptor to LIF on human PMN leukocytes.