Objective： To study multi-directional derivation of cord blood mononuclear cells to CD3AK, LAK and CIK cells as well as changes of killing activity to gastric cancer cell strain in vitro. Methods： CD3mAb and IL-2 were used to induce CD3AK cells, and IL-2 was used to induce LAK cells; IFN-γ was used in the beginning, then IL-1, CD3mAb and IL-2 were used to induce CIK cells after 24 h for observing amplification and analyzing their relationship. The phenotypes of the cultured CIK cells were analyzed by flow cytometry. Subsequently, by using MGC-803 gastric cancer cell strain as target cells, the killing activity of CD3AK, LAK and CIK cells was evaluated by using MTT method. Results： The amplification activity of CD3AK and CIK cells was all far higher than LAK cells （P〈0.05）. The amplification activity had no obvious difference between CIK cells and CD3AK cells at prophase, but that was far higher in CIK cells than CD3AK cells at about 20^th day （P〈0.05）. The flow cytometry revealed that the amount of CD3^＋ CD56^＋ cells, major effector cells after CIK cells being cultured was significantly increased （P〈0.05）, moreover, the amount of CD8^＋ cells was significantly increased as well （P〈0.05）. The killing activities of CD3AK and CIK cells to the MGC-803 gastric cancer cell strain were all significantly higher than LAK cells, while the killing activity of CIK cells was stronger than CD3AK cells （P〈0.05）. Conclusion： CIK cells have stronger amplification activity and killing activity, and can be taken as more effective killing cells applied to the tumor adoptive immunotherapy.
