Abstract: Objective To investigate the effects of dendritic cells pulsed with lysed K562 cells frozen-thawed antigen(ACL) and treated with sodium selenite(Se) on inducing the cytotoxic T lymphocyte(CTL) to get specific anti-tumor activity in vitro. Methods 1) The culture of DCs: In RPMI-1640(10% FBS) medium containing 3 cytokines(rhGM-CSF, rhIL-4 and TNF-α), the peripheral blood mononuclear cells(PBMNC) from healthy donor were cultured for 4 days, the adherent cells(DCs) were harvested; 2) The 4 groups of DCs: DC-Ⅰ: DCs only in the above culture system, DC-Ⅱ: adding of 0.5 μmol/L Se, DC-Ⅲ: adding ACL, DC-Ⅳ: adding both 0.5 μmol/L Se and ACL; 3) Induction of the effective cell-CTL: non-adherent cells(suspending cells) cultured in the RPMI-1640(10% FBS) with IL-2 for 2 days were cultured alone or with several DC groups for another 5 days; 4) Detection of CTL activity: The cytotoxicity was determined with LDH release method, using K562 cells as target cells. Results The CTLs induced in DC-Ⅱ, DC-Ⅲ and DC-Ⅳ groups had more potential effects on killing target cells than that induced in the DC-Ⅰ group, as well as in the T cell alone group, and their abilities increased along with elevation levels of the ratio of effective cells( E) to target cells(T). At the ratio of 25∶1, the rates of K562 cells killing in the groups of T cell alone, T-DC-Ⅰ, T-DC-Ⅱ, T-DC-Ⅲ and T-DC-Ⅳ were 5.9%±2.4%, 15.3%±2.3%, 26.3%±3.7%, 28.2%±4.5% and 36.2%±3.7% respectively, the activity of CTL in T-DC-Ⅳ group was the strongest, it was significantly more potent as compared with those in other groups. Conclusion Dendritic cells can be successfully generated from PBMNC by culture system supplied with rhGM-CSF, rhIL-4 and TNF-α in vitro. Both DC-groups loaded with ACL loaded and treated with Se can induce specific CTL responses and they have a synergistic effects on killing leukemia cells.

Key words: leukemia, dendritic cell, sodium selenite, frozen-thawed antigen