Lipid abnormalities in foam cell reticulosis of mice, an analogue of human sphingomyelin lipidosis

The lipid changes in the inheritable foam cell reticulosis of mice discovered by Lyons, Hulse, and Rowe have been reexamined. The major abnormality in thymuses from homozygous-abnormal animals has been identified as an increase in the concentration (per milligram of protein) of sphingomyelin and cholesterol. This increase is associated with normal sphingomyelin-cleaving activity. The lipid compositions of the liver and spleen in the homozygous-abnormal animal and of the thymus in the heterozygous-abnormal mouse are normal. The disorder appears to be chemically analogous to those forms of human sphingomyelin lipidosis (Niemann-Pick disease) that are not accompanied by a decrease in tissue sphingomyelinase.