Human serum contains a lectin which inhibits hepatic uptake of glycoproteins.

Human serum will inhibit the specific uptake of N-acetylglucosamine-terminated glycoproteins by isolated rat hepatic sinusoidal cells. The serum inhibitors are not glycoproteins that bind to the hepatic mannose/N-acetylglucosamine receptor but have the properties of lectins which bind to mannose/N-acetylglucosamine-terminated glycoproteins. They can be isolated from serum by affinity chromatography. The predominant lectin, with a molecular mass of less than 35 kDa, will inhibit the sinusoidal cell uptake of glycoproteins in vitro.