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AIM To study the activation of CTLs against gastric cancer cells induced by FasL/B7-l (FB-ll)genes modified tumor cells, and to explore whether co-expression of FasL and B7-1 in SGC-7901 tumor cells could initiate an synergistic antitumor effect. METHODS FasL and B7-1 genes were transfected into human SGC-7901 gastric cancer cells with adenovirus vectors. The positive clones were selected by G418. FasL and B7-1 were detected by Flow cytometry and RT-PCR .The abdominal infiltrating lymphocytes and sensitized spleen cells were obtained from the mice who were immunized with SGC-7901/FB-11 or wild type SGC-7901 cells intraperitoneally, and the cytotoxicity of these CTLs against tumor cells was determined by MTT assay. RESULTS Flow cytometry and RT-PCR showed that FasL and B7-1 were highly expressed. FasL+/B7-Â¿SGC-7901 cells (SGC-7901/FB-11) were inoculated subcutaneously in the dorsal skin of C57BL/6 mice and then they decreased their tumorigenicity greatly (p < 0.01). The SGC-7901/FB-11 cell-sensitized mice obtained the protective immune activity against the rechallenge of wild type SGC-7901 cells (p < 0.05). It was showed that the cytotoxicity of CTLs induced by SGC-7901/FB-11 cells against SGC-7901 was significantly higher than that of CTLs activated by wild-type SGC-7901 cells (p < 0.05). CONCLUSION The results suggest that the FasL and B7-1 can effectively promote the activity of CTLs against gastric cancer cells. And FasL/B7-l molecules play an important role in CTL cytotoxicity function as well. After introduced into SGC-7901 cells, Ad-B7-1 shows enhanced therapeutic efficiency for SGC-7901 cells when combined with Ad-FasL.