Distribution of lysosomal enzymes in different types of rat liver cells

Abstract

Eight lysosomal enzymes were measured in different types of rat liver cells. Hepatocytes were purified by low speed centrifugation of a cell suspension obtained by treating the perfused liver with collagenase. Nonparenchymal cells (NPC) were purified by centrifugation after treating the initial cell suspension with pronase, which selectively destroys the parenchymal cells (PC). Kupffer cells were found to attach selectively to tissue culture dishes after overnight culture of an NPC suspension. The specific activity of lysosomal enzymes was generally higher in NPC than in hepatocytes, but the different enzymes were concentrated to different degrees in the NPC. Specific activity of acid phosphatase was 1.7 times higher in NPC than in hepatocytes. Specific activity of acid DNAase, on the other hand, was 8 times higher in NPC than in hepatocytes. Other enzymes showed intermediate values. Assuming that 30% of the liver cells are nonparenchymal it may be calculated that from 7% (acid phosphatase) to 25% (acid DNAase) of the hepatic lysosomal enzymes are present in the NPC. The pattern of lysosomal enzymes in cultured Kupffer cells was similar to that of the NPC from which the Kupffer cells were derived. Cathepsin D and β-glucuronidase were, however, elevated in Kupffer cells as compared with NPC. The enzyme pattern in Kupffer cells was almost identical with that of rat peritoneal macrophages.