[Effects of IL-21 alone or in combination with IL-15/IL-2 on proliferation and anti-tumor activity of G-CSF-mobilized peripheral blood mononuclear cells in vitro].

This study was purposed to investigate the proliferation and antitumor activity of rhG-CSF-mobilized peripheral blood mononuclear cells (G-PBMNCs) activated by interleukin 21 (IL-21) alone or in combination with interleukin 15 (IL-15)/interleukin 2 (IL-2) and to evaluate the feasibility and value of tumor immunotherapy with cytokine combinations. G-PBMNCs were activated by IL-21 alone or in combination with IL-15/IL-2 in vitro, and the proliferation of the activated G-PBMNCs was analyzed by CCK-8 assay. The cytotoxicity of the activated G-PBMNC to the K562 cells was studied by the test principle which is based on target cell labeling with 5-(6)-carboxy-fluorescein succinimidyl ester (CFSE) and subsequent DNA-labeling with propidium iodide (PI) for identification of target cells with compromised cell membranes. The phenotypes of the activated G-PBMNCs were assayed by flow cytometry. The results showed that the cytotoxicity of IL-21 group had no difference from which of IL-2 group. When G-PBMNCs were exposed to the combinations of IL21+IL15/IL21+IL15+IL2, the cytotoxicity was significantly enhanced at E:T ratio of 25:1, as compared with combination of IL21+IL2 (p<0.05). The cytotoxicity of the cytokines combinations was significantly higher than that in cytokine used alone at E:T ratio of 50:1 (p<0.05). The cryopreservative and resuscitative G-PBMNCs showed the same result with the fresh G-PBMNCs in cytotoxicity test. The proportions of CD3+ and CD8+ T cells were increased when G-PBMNCs were incubated with cytokines for 72 hours. CD4, CD3-56+ and CD3+56+ counts were significantly elevated when G-PBMNCs were exposed to IL21 + IL15 (p<0.05). It is concluded that IL-21 alone enhance the antitumor activity of G-PBMNCs, which further strengthens when IL-21 combinated with IL-15.