CD44high Vγ4 γδ T cells were sorted from either B6 wild-type mice, or perforin−/− or IFNγ−/− mice spleens and lymph nodes, and stimulated with UC3 antobody in the presence of IL-2 for 8 days. B16 F0 tumor cells (2×105 cells/mouse) were mixed with these expanded Vγ4 γδ T cells (0.5×105 cells/mouse), injected into B6 TCR δ−/− mice (n =10 per each group) subcutaneously. Tumor growth was observed and recorded daily, Tumor size greater than 4×4 mm2 was considered positive. Data represent 3 independent experiments. *, p < 0.05. **, p < 0.01.