放疗对食管癌患者血清可溶性MICA含量及外周血NK细胞功能的影响

目的探讨经不同剂量高能X线照射后食管癌患者血清可溶性MHC—I类分子链相关基因A（sMI-CA）含量、自然杀伤细胞（NK细胞）表面NK细胞2族成员D（NKG2D）受体的表达及其杀伤毒性的变化。方法采用ELISA法检测中晚期食管癌患者（n=28）和正常对照（n=21）血清sMICA的含量，并动态分析6例食管癌患者经不同剂量高能X线照射后血清sMICA含量的变化。采用流式细胞术检测NK细胞NKG2D受体的表达，胞内染色法分析NK细胞杀伤靶细胞功能的变化。结果与正常对照相比，食管癌患者血清sMICA含量明显升高，但不同放疗剂量对食管癌患者血清sMICA含量无显著影响。食管癌患者外周血阳性表达NKG2D的NK细胞比例与正常对照相比显著降低，同时其细胞毒活性亦明显降低。而且与治疗前相比，40～60Gy的放疗剂量时NKG2D阳性的NK细胞数增加，同时其NK细胞毒活性最强。结论放疗对食管癌患者血清sMICA含量无明显影响，但适量放疗可使NK细胞毒活性增强。

Effects of irradiation on the serum soluble MICA level and the peripheral NK cell cytotoxicity in esophageal cancer patients

Objective To investigate the variations in the level of serum soluble MHC class I chain - related gene A （sMICA） , the expression of the surface receptor natural killer group 2 member D （NKG2D） on natural killer （NK） ceils and the cytotoxicity of peripheral NK cells in esophageal cancer patients by irradiation. Methods The concentration of serum sMICA protein from medium and advanced esophageal cancer patients （n = 28） and normal controls （n = 21 ） were determined by ELISA, and the variations in the serum sMICA level were dynamically observed throughout the treatment with different doses of irradiation in 6 esophageal cancer patients. The NKG2D expression on NK ceils were measured by flow cytometry, and the cytotoxicity on target cells was evaluated by intracellnlar staining with perforin antibody. ResultsIn contrast to normal controls, serum sMICA level significantly increased in esophageal cancer patients; however, irradiation at different doses did not markedly affect the serum sMICA levels. The percentage of NKG2D - positive NK ceils and their cytotoxicity significantly decreased. Furthermore, although there was no statistic variations in serum sMICA before and after irradiation, the percentage of NK cells and their cytotoxicity were enhanced at the irradiation dose of 40 - 60 Gy subsequent to the treatment and meanwhile, the NK cell cytotoxicity was at its peak. Conclusions Irradiation has no direct effects on the serum sMICA levels, whereas irradiation at adequate doses will promote the cytotoxicity of NK cells.