树突状细胞对CIK细胞中CD+4CD+25 T细胞数量及免疫调节作用的影响

目的探讨CD4+CD2+5调节性T细胞(Tregs)对细胞因子诱导的杀伤细胞(C IK)增殖及杀伤活性的影响;同时分析树突状细胞(DC)在逆转Tregs细胞免疫抑制效应中的作用。方法分别利用培养前分选去除CD4+CD25+T细胞的外周血单个核细胞和常规PBMC,分别培养C IK,检测细胞增殖和杀伤活性;同时在培养前去除Tregs组(C IK-Tregdel)中加入CD4+CD2+5T细胞,检测细胞杀伤活性的变化。利用DC诱导C IK细胞,分别检测DC+C IK及单纯C IK组中Tregs细胞的比例、细胞杀伤活性和TGF-β、IL-10等细胞因子的分泌水平。结果培养前去除Tregs组中增殖细胞比例、细胞杀伤活性均高于常规C IK组,在C IK-Tregdel组加入分选的CD4+CD25+细胞后,C IK的杀伤活性降低。DC诱导前后C IK中CD4+CD2+5细胞含量分别为13%±5%和10%±4%(t=3.977,P=0.001),证实经DC细胞诱导后C IK细胞中的Tregs数量减少,同时,观察到CD8+、CD3+CD5+6细胞增加;DC+C IK组对肺癌细胞系A549、乳腺癌细胞系MCF-7、结肠癌细胞系HCT-8和淋巴瘤细胞系Raji的杀伤活性分别为49.47%、32.78%、40.28%、47.11%,均高于单纯C IK组(P均<0.05);另外,C IK及DC+C IK组TGF-β分泌分别为546 pg/m l±134 pg/m l、489 pg/m l±132 pg/m l,IL-10分别为107 pg/m l±32 pg/m l和92 pg/m l±32 pg/m l,证实经DC诱导后C IK细胞TGF-β和IL-10分泌水平低于DC诱导前;同时,观察到DC+C IK组IFN-γ和IL-6分泌高于单纯C IK细胞(P<0.05)。结论DC细胞可以增强C IK的抗肿瘤活性,而其对Tregs细胞的影响很可能是DC活化C IK的机制之一。

Dendritic cells reduce the number and function of CD4+CD25+ cells in cytokine-induced killer cells

OBJECTIVE: To investigate the influence of dendritic cells (DCs) on the prevalence and function of regulatory T cells (Tregs) in cytokine induced killer (CIK) cells. METHODS: The blood samples of 20 patients with solid tumors were collected. The peripheral mononuclear cells (PBMCs) were isolated. CIK cells were added into the culture fluid without CD(4)(+)CD(25)(+)T cells (CIK-Treg(del) cells) and the culture fluid of regular PBMCs respectively, and the proliferation and cytotoxicity of the CIK cells were detected by BrdU method and with the cells of human lung carcinoma, breast carcinoma, colon carcinoma, and lymphoma as target cells respectively. CD(4)(+)CD(25)(+)T cells were added into another culture fluid of CIK-Treg(del) cells at the proportions of 20:1, 10:1, and 5:1 respectively, then the proliferation and cytotoxicity of the CIK cells were detected as described above. Flow cytometry was used to detect the surface markers of CIK cells. To identify the influence of DCs on the anti-tumor activity of CIK, PBMCs were isolated from the patients with solid tumor to culture the DCs and CIK cells. Dendritic cells were harvested on day 7 and co-cultured with the CIK cells (DC+CIK cells). The frequency of Tregs in CIK was determined by flow cytometry. The cytotoxicity was examined by LDH assay. The levels of TGF-beta, IL-10, IFN-gamma, IL-2, and IL-6 were analyzed by ELISA. RESULTS: The rates of the main effector cells in CIK cells (CD(3)(+)CD(56)(+) cells) were 17% +/- 5% and 28% +/- 5% in the regular CIK cells and CIK-Treg(del) cells respectively. LDH method showed that the cytotoxicity towards tumor cells of the CIK-Treg(del) cells The rates of the main effector cells in CIK cells (CD(3)(+)CD(56)(+) cells) were 17% +/- 5% and 28% +/- 5% in the regular CIK cells and CIK-Treg(del) cells respectively. LDH method showed that the cytotoxicity towards tumor cells of the CIK-Treg(del) cells was higher than that of the regular CIK cells (P < 0.05), however, after the addition of selected cells, the cytotoxicity of the CIK-Treg(del) cells decreased. Flow cytometry showed that the proportions of CD(4)(+)CD(25)(+) Treg cells in the CIK cells and DC-CIK cells were 13% +/- 5% and 10% +/- 4% respectively (t = 3.977, P = 0.001). After the DC induction the cytotoxicity of CIK cells was significantly higher than that of the regular CIK cells. ELISA showed that after DC induction the levels of TGF-beta and IL-10 of the DC+CIK group were significantly lower than those of the regular CIK cells (t = 2.136, P = 0.046; and t = 2.965, P = 0.008), and the level of IFN-gamma was significantly higher in the DC+CIK group (t = 2.220, P = 0.039). CONCLUSION: CD(4)(+)CD(25)(+) regulatory T cells inhibit the anti-tumor activity of CIK cells. The interaction between CIK cells and DCs is sufficient for the blockage of the properties of regulatory T cells. CIK cells have the desirable properties for immunotherapy approaches, especially after co-culture with DCs.