NK cell IFN-γ mediates the antimetastatic effect of α-GalCer initiated by NKT cell IFN-γ secretion.
(A) Groups of B6 Jα281−/− mice were inoculated intravenously with 5 × 105 B16F10 tumor cells. Three hours later, these mice received intravenous adoptive transfer of 2.5 × 105 sorted liver NK1.1+ T cells or NK1.1− T cells from B6 WT, B6 pfp−/−, B6 TNF−/−, or B6 IFN-γ−/− mice. Some groups of mice were treated intraperitoneally with 2 μg α-GalCer (▨) or vehicle control (▪) on days 0 (3 hours after tumor inoculation), 4, and 8 after tumor inoculation, as indicated. (B) Groups of B6 Jα281−/− mice were inoculated intravenously with 5 × 105 B16F10 tumor cells. Three hours later, these mice received intravenous adoptive transfer of sorted liver NK1.1+ T cells (between 0 and 2.5 × 105cells) from B6 WT mice, as indicated. All groups of mice were treated intraperitoneally with 2 μg α-GalCer on days 0 (3 hours after tumor inoculation), 4, and 8 after tumor inoculation. (C) Groups of B6 Jα281−/−, B6 IFN-γ−/−, B6 CD1d−/−, B6 RAG-1−/− mice, or B6 RAG-1−/− mice treated with anti-asGM1 antibody (as above) were inoculated intravenously with 5 × 105 B16F10 tumor cells. Three hours later, these mice received intravenous adoptive transfer of 2.5 × 105 sorted NK1.1+ T cells from B6 WT mice, 4.0 × 105 purified NK1.1+TCRαβ− NK cells, or both. Some groups of mice were treated intraperitoneally with 2 μg α-GalCer or vehicle control on days 0 (3 hours after tumor inoculation), 4, and 8 after tumor inoculation, as indicated. ND, not determined. In all experiments, 14 days after tumor inoculation the lungs of these mice were harvested, and B16F10 tumor colonies counted and recorded as the mean number of colonies ± SE. The number of mice in each group is indicated in parentheses, and asterisks indicate the groups in which α-GalCer treatment significantly reduced the number of lung metastases compared with untreated or vehicle control (Mann-Whitney U: *P < .05; **P < .001).
