Effects of inducible co-stimulator gene on the cytotoxic activity of cytokine-induced killer cells against cholangiocarcinoma cells

Objective To explore the effects of inducible co-stimulator (ICOS) gene on the cytotoxic activity of cytokine-induced killer (CIK) cells against cholangiocarcinoma cells. Methods CIK-ICOS cells were obtained by stable transfecting ICOS genes into CIK cells through the adenovirus vector whereas untransfected and EGFP-transfected CIK cells were treated as controls. The proliferation and apoptosis of different CIK cells, as well as their cytotoxicity against cholangiocarcinoma cells in the three groups were detected. The expressions of IFN-T, IL-2 and TNF-α in the supernatant of different CIK cells were measured by ELISA. SCID mice with cholangiocarcinoma were randomly divided into CIK group, CIK-EGFP group, CIK-ICOS group and normal saline group. The cytotoxic activity of CIK-ICOS cells against cholangiocarcinoma cells in vivo was observed. Results CIK-ICOS cells displayed better proliferation than CIK cells and CIK-EGFP cells. At day 20 and 23 of culture, the apoptosis rate of CIK-ICOS cells was 0.69% and 0.89%, respectively, while that of the CIK cells was 2.90% and 4.92%. The cytotoxic effect of CIK-ICOS cells at different E: T ratio against cholangiocarcinoma cells was significantly stronger than that of CIK cells and CIK-EGFP cells (F=13.37, 6.46, 25.51, P<0.05). The concentration of IFN-γ in CIK-ICOS cultured supernatant was (49.50±4.73)μg/L, which was significantly higher than that in the cultured supernatant of CIK cells [(30.53±3.73)μg/L] and CIK-EGFP cells [(30.12±2.64)μg/L](F=38.89, P<0.05). The growth of cholangiocarcinoma was significantly slower in CIK-ICOS group than that in CIK group and CIK-EGFP group, whereas the necrosis area of tumor was larger and the CIK cells in CIK-ICOS group was more than those in the other two groups. Conclusions CIK cells had the function of killing cholangiocarcinoma cells in vitro and in vivo. After ICOS genes were transfected into CIK cells, the survival time of CIK cells in vitro was prolonged and the proliferation of CIK cells was enhanced, as well as the secretion of IFN-γ was increased so that the cytotoxicity of CIK cells against cholangiocarcinoma cells in vitro and in vivo was enhanced. Key words: Cholangiocarcinoma;  Inducible co-stimulator;  Cytokine-induced killer cells