不同淋巴细胞亚群NKg2D的表达与结肠癌发病关系的研究

目的探讨不同淋巴细胞亚群表面NKg2D受体的表达与结肠癌发病的关系。方法首先收集10例结肠癌组织、外周血及相应肿瘤组织引流淋巴结和11例正常个体的外周血,分别用免疫组化检测肿瘤组织内NKg2D阳性淋巴细胞的数目,用流式细胞仪检测外周血及引流淋巴结内NKg2D阳性的总淋巴细胞数、CD8+T细胞数、γδT细胞数及NK细胞数。结果结肠癌肿瘤组织内无NKg2D阳性的淋巴细胞,患者外周血NKg2D+NK细胞与正常个体相比明显减少(P=0.03),发生肿瘤转移的淋巴结内总淋巴细胞NKg2D的表达与同一个体外周血的相比,迅速降低(P=0.006),而且转移淋巴结内NKg2D+γδT细胞也明显减少(P=0.049)。结论结肠癌细胞可通过抑制NKg2D的表达而减弱机体的免疫功能。

Correlation between Expression of NKg2D on lymphocytes and the Development of Colon Cancer

Objective To study the correlation between the expression of NKg2D and the development of colon cancer.Methods We analyzed the expression of NKg2D on 10 primal tumor tissues,peripheral blood and 10 drained lymph nodes of colon cancer patients and 11 peripheral blood samples from healthy controls.NKg2D positive cells in tumor tissues were detected by the method of immunochemistry.The percentage of NKg2D positive cells in total lymphocytes,CD8+ T cells,γδT cells and NK cells were observed by flow cytometry.Results We didn′t observe the expression of NKg2D on lymphocytes in primal cancer cells,the percentage of NKg2D and CD56 double positive cells in patients was significantly lower than that in healthy controls.The expression of NKg2D on lymphocytes from lymph nodes with metastasis decreased dramatically compared with corresponding peripheral blood lymphocytes,especially the expression of NKg2D onγδT cells.Conclusion Our results suggested that cancer cell may acquire evasion from immune surveillance through decreasing the expression of NKg2D.In addition,monitoring the expression of NKG2D on peripheral lymphocytes may not be a sensitive biomarker for evaluation the metastasis of tumor to lymph nodes.