转B7-1基因的人多发性骨髓瘤细胞XG-7在激发杀肿瘤细胞CTL中的作用

The Role of Myeloma Cells XG-7 Transfected with B7-1 Gene in Activating Tumor-killing CTL

为调查B7－1分子在人多发性骨髓瘤细胞的表达是否可诱导出具有抗肿瘤作用的CD8+的CTL，我们用含B7－1基因逆转录病毒载体PTG5192的包装细胞293E的培养上清，感染人多发性骨髓瘤细胞系XG－7（不表达B7－1分子），用新霉素G418选择并经流式细胞仪筛选，获得了稳定高表达B7－1分子的XG－7细胞（命名为XG－7－B7细胞）。在体外增殖实验中，XG－7－B7细胞显示出比母系细胞XG-7对外周血淋巴细胞（PBL）具有更大的刺激活性。表型分析证实XG-7-B7细胞所刺激的PBL是一群T细胞，其表型特征为CD3，CD8阳性，CD25、CD28也高表达，而CD4和CD16几乎不表达。这群细胞可在体外长期培养扩增，并可用作效应细胞。细胞毒实验结果表明：CD8+T细胞可杀死XG－7－B7细胞、母系细胞XG－7和其它肿瘤细胞如K562与Daudi细胞。结果提示，这群肿瘤持异的CD8+CTL细胞对肿瘤的过继免疫治疗具有潜在的应用价值。

B7 (including B7-1 and B7-2 ) costimulation is necessary to fully activate T cells upon antigen recognition by T cell receptor. To investigate whether expression of B7 molecule on human myeloma cells may render these cells able to elicit CD8+ cytotoxic T Tymphocyter (CTL)-dependent antitumor responses, we used the culture supernatant of packing cell line 293E containing B7-1 gene retroviral vector PTG5192 to infect a human myeloma cell line XG-7, which did not express B7-1 molecule. After selection by neomycin G418 and screening by cytometer, we obtained the subline XG-7 with high and stable expression of B7-1 molecule (named XG-7-B7). In proliferative assay, XG-7-B7 cells showed greater activity stimulating the proliferation of peripheral blood lymphocytes (PBL)compared to parental XG-7 cells. The phenotype analysis demonstrated that PBL stimulated by XG-7-B7 was CD3+, CD8+, CD=25+, CD28+ but CD4, CD16- T cell subpopulation. In addition, this subpopulation, which could be cultureed in the long term in vitro, was used as effector cells. The results of cytoloxicity showed that these CD8+ T cells were capable of killing not only XG-7-B7 cells but also parental XG-7 cells as well as the other tumor cells such as K562 and Daudi cells, suggesting that these tumor-specific CD8 + CTL may be useful for adoptive immunotherapy of tumors.