人CD137L在肿瘤细胞上的表达及其功能研究

为研究不同来源人肿瘤细胞系表面cD137L的表达和功能。采用RT-PCR、FACS方法检测人CD137L在肿瘤细胞的表达,运用ELISA的方法检测CD137L对T细胞释放IFN-γ的影响及对肿瘤细胞分泌IL-8的影响。结果:来源于肝癌、肺癌、结肠癌、白血病的9种人肿瘤细胞系均可不同程度表达CD137L,但CD137L的表达水平与肿瘤细胞系的来源无相关,同一组织来源的细胞系,有的高表达,有的低表达。胚胎细胞系ECV 304中度表达CD137L,而正常新分离的PBMC不表达。功能研究发现:L78肿瘤细胞上表达的CD137L在CD3单抗存在的情况下与T细胞上的CD137L结合,能提高T细胞释放IFN-γ的水平,其作用具有剂量依赖性,这种作用可被抗-CD137L阻断;而CD137L表达水平与L78相似的Hep G2.2.15细胞在CD3单抗存在下并不能增强T细胞IFN-γ的分泌,进一步分析发现Hep G2.2.15同时表达较高水平的CD137(大约为91.6％),而L78几乎不表达CD137。肿瘤细胞上CD137L与表达在CHO细胞表面的CD137相互作用对肿瘤细胞分泌IL-8的水平产生不同的影响,使Hep G2.2.15分泌IL-8的水平约增加2倍(从15 pg/ml增加到30 pg/ml),但对肿瘤细胞HLE、A2分泌IL-8没有明显影响。CD137L在肿瘤细胞上的表达是普遍现象,其表达可能与细胞的快速生长有关;某些肿瘤细胞系表达的CD137L是有功能的,一方

Expression and Functional Analysis of Human CD137L on Tumor Cells

The expression and functional analysis of human CD137L on tumor cells from different sources were investigated by RT-PCR and FACS, and the level of IFN-γreleased from T cells induced by CD137L and the level of IL-8 secreted by the tumor cells were detected by ELISA. It was found that 9 human tumor cell lines from different origins (i.e. liver cancer, lung cancer and colon cancer ) could express CD137L, but the levels of expressions were different among different tumor cell lines, the ECV 304 cell line of embryonic origin moderately expressed this ligand, yet normal human peripheral blood mononuclear cell (PBMC )didn't show any expression. The expression level of CD137L on tumor cell lines had no association with the histological origin of tumor cells. Functional analysis revealed that the CD137L expressed on the tumor cell L78 could bind with the CD137 on T cells and enhance the release of IFN-γ from T cells in the presence of anti-CD3 monoclonal antibody. This action was dose-dependent and could be blocked by anti-CD137L antibody. However, Hep G2.2.15 cells expressing the similar level of CD137L to L78 cells didn 't show enhancing effect on T cells to secrete IFN-γ. The CD137L on tumor cells appeared to have different influences on the secretion of IL-8 by tumor cells, i.e, it could elevate the level of IL-8 secretion on the Hep G2.2.15 cells up to two times (from 15 pg/ml up to 30 pg/ml ) , but showed no significant influence on the secretion of IL-8 on HLE, and A2 cells. It concludes that the expression of CD137L on tumor cells is a common phenomenon and might be related with the rapid growth of tumor cells.