Immunostimulatory Activities of Monoglycosylated Alpha-D-pyranosylceramides

We compared the immunostimulatory effects of chemically synthesized alpha-galactosylceramides (alpha-GalCers), alpha-glucosylceramides (alpha-GluCers), 6"-monoglycosylated alpha-GalCer and 6"- or 4"-monoglycosylated alpha-GluCer and made the following observations: (1) the length of the fatty acid side chain in the ceramide portions greatly affects the immunostimulatory effects of alpha-GalCers and alpha-GluCers; (2) the configuration of the 4"-hydroxyl group of the inner pyranose moiety plays an important role in the immunostimulatory effects of monoglycosylated alpha-D-pyranosylceramides; (3) the free 4"-hydroxyl group of the inner pyranose of monoglycosylated alpha-D-pyranosylceramides plays a more important role in their immunostimulatory effects than the free 6"-hydroxyl group.