Sphingolipid metabolism in leucocytes. I. Incorporation of(14)C-glucose and (14)C-galactose into glycosphingolipids by intact human leucocytes.

Glucosyl ceramide and lactosyl ceramide have been isolated from intact human leucocytes. Incubation of intact white blood cells with either(14)C-glucose or(14)C-galactose resulted in the incorporation of these tracers into the glycosphingolipids. The products were extracted by conventional procedures and purified by combined silicic acid column and thin-layer chromatography. The bulk of the radioactivity was found in the monohexoside and dihexoside ceramide fractions.Acid hydrolysis yielded glucose as the principal carbohydrate of the monohexoside ceramide, regardless of the sugar precursor employed. In the dihexoside ceramide fraction, galactose was liberated as the major sugar component. The specific activities of the lactosyl ceramide was found to be greater than that of the corresponding glucosyl ceramide.