Ito cells in lysosomal storage disorders. An ultrastructural study

An ultrastructural study was performed in a series of liver biopsies from patients with various lysosomal storage diseases to evaluate the extent of lysosomal hypertrophy and hyperplasia in Ito cells (ICs). In previous studies this has been considered to be absent or only rudimentary. Lysosomal storage was recognized by the presence of storage cytosomes surrounded by limiting membranes and by the appearance of their content which was identical to that in other hepatic storage lysosomes. Storage was found in sphingomyelinase deficiency (Niemann-Pick disease types A, B), in Wolman's disease, GM1 gangliosidosis, mucopolysaccharidosis and in multiple sulphatase deficiency. In type C Niemann-Pick disease it was virtually absent with the exception of cases with prominent hepatic symptomatology. Storage was of variable degree and was accompanied by a decrease in the physiological fat content (cytoplasmic lipid droplets). The degree to which ICs were affected correlated only with the extent to which nonspecific fibroblasts were involved in the specimens studied and thus seems to reflect storage in the fibroblastic population.