Cutting Edge: Inhibition of Experimental Tumor Metastasis by Dendritic Cells Pulsed with α-Galactosylceramide

Abstract

Abstract A unique lymphoid lineage, Vα14 NKT cells, bearing an invariant Ag receptor encoded by Vα14 and Jα281 gene segments, play crucial roles in various immune responses, including protective immunity against malignant tumors. A specific ligand of Vα14 NKT cells is determined to be α-galactosylceramide (α-GalCer) which is presented by the CD1d molecule. Here, we report that dendritic cells (DCs) pulsed with α-GalCer effectively induce potent antitumor cytotoxic activity by specific activation of Vα14 NKT cells, resulting in the inhibition of tumor metastasis in vivo. Moreover, a complete inhibition of B16 melanoma metastasis in the liver was observed when α-GalCer-pulsed DCs were injected even 7 days after transfer of tumor cells to syngeneic mice where small but multiple metastatic nodules were already formed. The potential utility of DCs pulsed with α-GalCer for tumor immunotherapy is discussed.