Fluorescent-labeled anti-inflammatory α-galactosylceramide derivative and its intracellular behavior associated with selective immune function

Immune activity is markedly modulated by glycolipid antigens through CD1d-dependent recognition, resulting in selective induction by NKT cells. In this study, we developed a novel and effective GalCer labeling method to apply to the anti-inflammatory α-GalCer-Bz amide that possesses Th2-biased cytokine induction ability. Using these fluorescent-labeled antigen probes, the uptake of the synthesized KRN7000-type and α-GalCer-Bz amide-type labeled compounds into CD1d-expressing cells was observed by confocal microscopy. The antigen presentation on the cell surface was also tracked with visualizing the complex of CD1d and glycolipid antigens. The intracellular behavior of α-GalCer-Bz amide-type showed that its efficient cellular uptake is highly dependent on the presence of CD1d, while it rapidly presented on the cell surface as the CD1d-complex. The findings on the characteristic cellular behavior of the glycolipid antigens provide basis for further understanding of the immune modulation.