Establishment of dendritic cell immunotherapy based on the chemokine expression profile of cancer cells

已有研究表明，DC与肿瘤细胞融合后可作为抗原提呈细胞（APC）发挥功能，并含有肿瘤特异性抗原。一些DC/Tumor融合细胞的临床试验表明，在晚期疾病患者中，肿瘤消退明显。在我们的研究中，DC和照射的肿瘤细胞以1：1的比例混合，并在含有50%聚乙二醇（PEG）的无血清RPMI 1640培养基中孵育1分钟以诱导细胞融合。然后，我们使用电融合技术生产融合细胞。在初步研究中，确定了最佳细胞数量（1.0 × 10^6个DC：1.0 × 10^6个肿瘤细胞/mL）和对齐电压（100 V，10秒）。采用ECM 2001电融合仪进行细胞融合，并通过荧光显微镜和流式细胞仪进行确认。DC与同种异体胃癌细胞成功融合，产生作为抗原呈递细胞的杂交细胞，因为它们诱导同种异体CD 4 + T细胞增殖。胃癌细胞系MKN-45和DC杂交细胞诱导自体CD 4+和CD 8 + T细胞增殖，表明MKN-45-DC杂交细胞将MKN-45细胞的一些抗原呈递给CD 4+和CD 8 + T细胞。当用于免疫时，由MKN-45-DC杂交细胞刺激的CD 8 + T细胞能够杀死MKN-45。CTL杀死了另一种胃癌细胞系MKN-1，以及黑色素瘤细胞系888 mel，这表明了对共享肿瘤抗原的识别。MKN-45特异性CTL可以识别癌胚抗原（CEA），表明杀伤是由于肿瘤抗原以及同种异体抗原。DC/肿瘤融合细胞在肿瘤治疗中的实际应用需要进一步的研究。此外，肿瘤细胞对免疫细胞的反击机制应被阐明，以建立有效的DC治疗癌症。

Some previous reports indicated that fusion cells of DCs and tumor cells could function as antigen-presenting cells(APCs) containing tumor specific antigens. Several clinical trials with DC/Tumor fusion cells demonstrated an obvious tumor regression in patients with advanced stage of disease. In our study, the DCs and irradiated tumor cells were mixed at a ratio of 1:1 and incubated in serum-free RPMI 1640 medium containing 50% polyethylene glycol(PEG) for 1 min to induce cell fusion. Then, we used electrofusion techniques for producing the fusion cells. In a preliminary study, the optimal cell numbers (1.0x10^6 of DCs : 1.0x 10^6 of tumor cells/mL) and alignment voltage (100V for 10sec) were determined. Cell fusion was performed using ECM2001 electrofusion apparatus and confirmed by fluorescent microscopy and flow cytometry. The DCs were successfully fused with the allogeneic gastric cancer cells resulting in hybrid cells that functioned as antigen-presenting cells, because they induced allogeneic CD4+ T cell proliferation. A gastric cancer cell line, MKN-45, and DC hybrid cell induced autologous CD4+ and CD8+ T cell proliferation, indicating that MKN-45-DC hybrids present some antigens from the MKN-45 cells to the CD4+ and CD8+ T cells. CD8+ T cells stimulated by the MKN-45-DC hybrid cells were able to kill MKN-45 when used for immunization. The CTLs killed another gastric cancer cell line, MKN-1, as well as a melanoma cell line, 888 mel, suggesting the recognition of a shared tumor antigen. MKN-45 specific CTLs can recognize carcinoembryonic antigen(CEA), indicating that the killing is due to tumor antigens as well as alloantigens. Further studies are requested for practical use of DC/tumor fusion cells in cancer therapy. Moreover, the mechanisms of counterattack by tumor cells against immune cells should be clarified to establish an effective DC treatment for cancer.