FLUORESCENCE-BASED DIAGNOSIS OF LIPID STORAGE DISEASES BY ANALYSIS OFTHE CULTURE-MEDIUM OF SKIN FIBROBLASTS

Glycosphingolipids, labeled with the fluorescent probe lissamine rhoda mine were administered to skin fibroblasts in culture and were hydroly zed in the intact cells to the corresponding lissamine rhodamine ceram ide (N-acylsphingosine). This fluorescent ceramide was converted in th e intact cells to the corresponding sphingomyelin which was secreted i nto the culture medium. In comparison, ceramide is not formed in cells derived from patients with lipid storage diseases, because of deficie ncies in lysosomal glycolipid hydrolases. Consequently, fluorescent sp hingomyelin was absent from the culture medium or present in considera bly reduced quantities. This provided a procedure for diagnosing lipid oses, by analyzing the lissamine rhodamine sphingomyelin content in th e culture medium, while maintaining the cells intact.