Abstract: Abstract:Objective To explore the  methods to induce and expand the  NK and CIK cells in vitro and to compare the proliferation abilities and anti-tumor activitiesof NK and CIK cells. Methods Peripheral blood mononuclear cells(PBMCs) were separated from the peripheral blood of cancer patients. The PBMCs were induced by cytokines to culture NK and CIK cells. The morphological changes of NK and CIK cells were observed. The percentages of CD3－CD56+NK and CD3+CD56+ CIK cells were detected by flow cytometry. And the expansion folds of NK and CIK cells were calculated. The levels of interferon-γ(IFN-γ) secreted by NK and CIK cells were detected by ELISA method. And the killing activities of NK and CIK cells against K562 cell strain were detected by CCK-8 method. Results After induction and expansion in vitro for 14 d,the NK cells expanded (160.00±12.15) folds,and the CIK cells expanded (110.00±15.48) folds. The expansion ability of the  NK cells was higher than that of the  CIK cells（P<0.05）.The secretion levels of IFN-γ in the supernatant of NK and CIK culture system raised to (4 227.75±731.94) and (525.96±304.84)  μg/L,respectively. The secretion level of IFN-γ of the NK cells was higher than that of the CIK cells（P<0.01）.After induction and expansion,the cytotoxicities of NK and CIK cells against K562 cells were enhanced with the increase of effector-target  ratio.The killing rates of NK and CIK cells against K562 cells were 65.35% and 57.68% at 25∶1 effector-target  ratio,respectively.The killingactivity of NK cells was higher than that of CIK cells at the same effector-target  ratio（P<0.01）.Conclusion The induction and expansion system of NK and CIK cells  in vitro is established successfully,and the expansion capability,the secretion level of IFN-γ,and the cytotoxicity of the NK cells are higher than those of the CIK cells.

Key words: natural killer cells, cytokine induced killer cells, killing activity