Nonenzymatically glycated serum albumin: interaction with galactose-specific liver lectins

The possible interaction of galactose/glucose-specific liver lectins with nonenzymatically glycated human serum albumin was analyzed. The binding activity of the asialoglycoprotein receptor on hepatocytes and of the corresponding lectin on Kupffer cells was determined using freshly isolated liver cells from Wistar rats. Nonenzymatically glucosylated or galactosylated human serum albumin (HSA) did not inhibit lectin binding in a competitive adhesion assay (less than 15% inhibition). In contrast, lactosylated HSA strongly interacted with the two liver lectins (more than 80% inhibition). Lectin binding increased with lactosylation reaching a maximum at 44-49 mol D-galactose bound per mol HSA. In conclusion, at least in certain cases, nonenzymatically glycated proteins may interact with endogenous lectins.