REQUIREMENT FOR α-L-FUCOSE ON THE MACROPHAGE MEMBRANE RECEPTOR FOR MIF

α-L-fucose abolishes the activity of guinea pig migration inhibitory factor (MIF) on the macrophages. Other sugars such as α-D-glucose, ß-D-galactose, α-L-rhamnose, methyl-α-D-mannoside, and N-acetyl-ß-D-glucosamine had no effect. Theabolition of MIF activity by α-L-fucose was reversible. When macrophages were incubated with α-L-fucosidase, a glycosidase which splits terminal α-L-fucose from oligosaccharides, the macrophages no longer responded to MIF. On the other hand, MIF incubated with α-L-fucosidase was still active. These experiments strongly suggest that α-L-fucose comprises an essential part of a macrophage membrane receptor for MIF.