CD1d blockade enhances production of IFN-γ by tumor-specific cells generated by RT + anti-CD137 co-stimulation. WT or iNKT−/− mice were treated with local tumor radiotherapy in two fractions of 12 Gy given on days 13 and 14 post-tumor inoculation. Mice received anti-CD137 mAb on days 15, 18 and 21. Some mice additionally received anti-CD1d mAb or isotype control on days 3, 7 and 11 post tumor inoculation. Cells from tumor-draining lymph nodes were collected on day 23 and stimulated with feeder cells pre-loaded with irrelevant peptide pMCMV (open circles) or AH-1-A5 (filled circles). Secreted IFN-γ in the supernatant was measured 48 hours later. Each symbol represents an individual mouse. Bars indicate the mean ± SD of 3–5 mice/group. *
p < 0.05, ***
p < 0.0005.