模拟失重对人自然杀伤细胞毒活性的影响

Effects of Simulated Weightlessness on Human NK Cell Cytotoxicity

目的研究模拟失重状态下人NK细胞的细胞毒活性并对其活性变化的机制进行初步的探讨。方法采用高均一性的人NK细胞作为模型,以回转细胞培养模拟失重状态。人NK细胞经历48h和72h的模拟失重后,测定其杀伤率,并在mRNA水平检测NK细胞穿孔素基因、激活性受体基因以及抑制性受体基因的表达水平。结果模拟失重48h和72h的人NK细胞,其杀伤率比对照组分别下降了16%(P<0.05)和26%(P<0.05)。通过对模拟失重72hNK细胞mRNA的定量分析,发现激活性受体NKG2D基因表达下调,抑制性受体NKG2A基因表达上调,而穿孔素基因表达没有显著性变化。经历72h模拟失重的人NK细胞,回到正常条件下培养6d后,其细胞毒活性才恢复至正常水平。结论模拟失重可以导致人NK细胞杀伤活性的下降,其原因可能与NKG2A及NKG2D受体表达的变化有关。

Objective To determine the effect of simulated weightlessness on cytotoxicity of human NK cells and to explore the mechanism of its changes on activating receptors,inhibitory receptors and perforin in cytolytic activity primarily. Methods Pure human NK cells obtained from＇NK ex vivo expansion system＇ were incubated in clinostat to simulate weightlessness. The cytotoxicity of human NK cells were tested after 48 h and 72 h simulated weightlessness. The expression levels of NKG2D,NKG2A and perforin genes were determined on mRNA level with real-time RT-PCR. Results The cytotoxicity of human NK cells decreased 16% （ P 〈 0.05 ） and 26% （ P 〈 0.05 ） respectively, after simulated weightlessness treatment for 48 h and 72 h. For the group of 72 h, the gene expression level of activating receptor NKG2D was down-regulated with quantitative analysis of NK cell mRNA, while inhibitory receptor NKG2A up-regulated. However, there was no significant change for the expression of perforin. The NK cytotoxicity recovered from the effect of simulated weightlessness after 6 d cultured in normal condition. Conclusion Cytotoxicity of human NK cells can decrease significantly after simulated weightlessness. Altered expression levels of NKG2D and NKG2A probably contribute to decrease cytotoxicity.