Lipolysosomes in human liver: distribution in livers with fatty infiltration

In this study we investigated whether lipolysosomes--lysosomes containing large lipid droplets--were present in livers of patients with various forms of hepatic injury. Organelles which displayed the same morphological characteristics and enzymatic activity as those originally described in the hamster and those found in the hepatocytes of patients with Wolman's or Wilson's disease were also found in hepatocytes of 13 of 14 randomly selected biopsy specimens from patients with minimal to severe fatty infiltration of the liver. The numbers and sizes of the lipolysosomes seemed to increase with the degree of fatty infiltration while their proportion in relation to the total number of lipid droplets remained below 5%. Based on these observations of a virtually constant association of lipolysosomes with excess lipid accumulation in liver cells we suggest that lysosomes probably play an important role in hepatic lipid metabolism and that various pathogenetic mechanisms may trigger their proliferation.