Uptake of beta-hexosaminidase by nonparenchymal liver cells and peritoneal macrophages

The uptake of beta-hexosaminidase (EC 3.2.1.30) in nonparenchymal liver cells (i.e. endothelial and Kupffer's cells) and peritoneal macrophages has been determined by an enzymatic assay. A considerable uptake was noted in nonparenchymal liver cells, whereas no measurable uptake was seen in peritoneal macrophages. The endothelial cells were more active in the uptake of beta-hexosaminidase than were the Kupffer's cells. The uptake of beta-hexosaminidase by nonparenchymal liver cells showed saturation kinetics and was competitively inhibited by mannan. These findings support the concept that a cell surface receptor on nonparenchymal liver cells mediates uptake of beta-hexosaminidase and suggests a difference in the receptor mechanisms on liver and peritoneal macrophages.