脐血源树突状细胞促进T细胞对肿瘤细胞的杀伤效应

本研究探讨人脐血单个核细胞体外诱导分化的树突状细胞（DC）促进T细胞对肿瘤细胞的杀伤效应。利用淋巴细胞分离液密度梯度离心法获取脐血单个核细胞,经贴壁法获得脐血贴壁的单个核细胞,经粒细胞-巨噬细胞集落刺激因子（GM-CSF）、白介素-4（IL-4）体外诱导分化为脐血DC。用间接免疫荧光法检测DC,MTT法检测DC活化的T细胞对肿瘤细胞的杀伤效应。试验组加DC,DC与肿瘤细胞的比例分别为20∶1、50∶1、100∶1,对照组不加DC。结果表明：脐血单个核细胞经GM-CSF、IL-4诱导后,第15天在倒置显微镜下可见典型形态的DC。荧光显微镜下,CD1a＋细胞率为（43.12±5.83）%。各实验组与对照组比较,实验组DC刺激的T细胞对肿瘤细胞的杀伤效应均高于对照组,差别均具有显著性（P〈0.01）。100∶1组与50∶1组比较,对肿瘤细胞的杀伤效应差别无统计学意义（P〉0.05）;100∶1组对肿瘤细胞的杀伤效应低于20∶1组,差别有统计学意义（P〈0.05）;50∶1组对肿瘤细胞的杀伤效应低于20∶1组,差别有统计学意义（P〈0.05）。结论：人脐血单个核细胞体外经细胞因子诱导分化培养的DC可促进T细胞对肿瘤细胞的杀伤效应。

Enhancing Effect of Dendritic Cells Derived from Human Cord Blood on T Cells in Killing Tumor Cells

Dendritic cells (DCs) derived from bone marrow cells are specialized cells for the uptake, processing, and presentation of foreign and self-antigens. The study indicated that re-transfusion of DCs pulsed with tumor-associated antigen can induce an vigorous specific anti-tumor response in clinic. The present study was aimed to investigate the enhancing effect of DCs derived from human cord blood on T cells in killing tumor cells. Human cord blood mononuclear cells were isolated from human cord blood by density gradient centrifugation using lymphocyte separating medium, and cord blood mononuclear cells were obtained by adherence and cultured in a liquid culture system with GM-CSF and IL-4 for 15 days. Then the cells were analyzed for phenotypes of CD1a by indirect immunofluorescence. The capacity of DCs to initiate T cell-dependent anti-tumor immune responses was assayed by MTT kit. The ratios of DCs to tumor cells in experimental groups were 20:1, 50:1 and 100:1 respectively. The DCs were not added in control group. The results indicated that in the presence of GM-CSF and IL-4, the DCs with typical morphological features at days 15 were observed. At that time, (43.12 +/- 5.83)% CD1a(+) cells were obtained. In addition to these phenotypic properties, the DC of experimental groups could remarkably initiate T cell-dependent anti-tumor immune responses with different ratios compared with control group (P < 0.01), there were no significant difference of killing effects between 100:1 and 50:1 groups (P > 0.05), and killing effect of DC in 20:1 group was higher than that in 100:1 or 50:1 groups (P < 0.05). It is concluded that human cord blood mononuclear cells can serve as a better source of DC, which can promote the capacity to initiate T cell-dependent anti-tumor immune responses.