Composition and biosynthesis of the major hexose containing sphingolipids of pig leucocytes

The oligohexosyl ceramides of two preparations of blood leucocytes taken from large white pigs, weighing 80 kg were analyzed and found to comprise as major constituents trihexosyl ceramide, with glucose-galactose in a molar ratio of 1∶2, and glucosyl ceramide. The mean value of the two preparations was 4.9% and 1.35% of the total lipids, respectively, for the two glycolipids. Lactosyl ceramide is the major component of human leucocytes, in contrast to the pig leucocytes where it was detected in minor quantities. U-¹⁴C-glucose, incubated with bone marrow cells of young pigs (20 kg living weight), was mainly incorporated into the carbohydrate moiety of glucosyl ceramide and trihexosyl ceramide. Further analysis of this compound indicated that all three hexoses were labeled with¹⁴C and that the glucose attached to the ceramide had the highest specific activity. Time studies showed a decline in the incorporation of¹⁴C into glucosyl ceramide as compared to its incorporation into trihexosyl ceramide.