Metabolism of sphingomyelin in cultured skin fibroblasts from patients with different types of Niemann-Pick disease

The metabolism of [choline-methyl-14C]sphingomyelin in cultured skin fibroblasts from patients with different types of Niemann-Pick disease was measured 1 and 3 days after uptake from the media. The cell lines obtained from type A disease had more than 95% unhydrolyzed sphingomyelin in situ on day 3 while two cell lines obtained from type B had 36.3% and 43.3% unhydrolyzed sphingomyelin on day 3. The cell line derived from one patient with the transitory type disease had 48.1% unhydrolyzed sphingomyelin on day 3, and there was no significant difference in the sphingomyelinase activity measured in vitro or in degradation of sphingomyelin in situ between the type B and transitory type disease. In three cell lines from patients with type C disease, there was 18.5%, 29.6% and 31.1% unhydrolyzed sphingomyelin on day 3, which indicates that this type has a decreased ability to metabolize sphingomyelin. Cell from type E disease metabolized sphingomyelin normally.