| Objective To investigate the effects of CpG-ODN on the expression levels of FasL and Fas in Jurkat and HeLa cell line, and to screen the optimal stimulating concentration and time of CpG-ODN for further studies; To explore the role of CpG-ODN on apoptosis induced by FasL- Fas signaling pathwayMethods After incubation with CpG-ODN for 12hours, HeLa and Jurkat cells were collected for the fluorescent quantitative real-time PCR of FasL and Fas mRNA at the concentrations from 0.001μmol/L to 10μmol/L to find out the optimal concentration;at the optimal concentration decided above,incubating HeLa and Jurkat cell with CpG-ODN up to 48hours, and then determine the maximal stimulating time; and the cell apoptosis induced by FasL-Fas pathway was examined by coculture assays of HeLa cells and Jurkat lymphoma T cell in vitro with flow cytometry.Results⑴CpG-ODN functions in a dose dependent mannar.Compared with the control, the relative expression ratios(rER) of FasL mRNA at concentration of 0.001μmol/L and 0.01μmol/L had no difference(p>0.05), at concentration of 0.1μmol/L , 1μmol/L ,and 10μmol/L there was a difference(p<0.05), but there was no significance between concentration of 1μmol/L and 10μmol/L in the treatment .⑵CpG-ODN functions in a time dependent mannar. Incubating HeLa and Jurkat cell with M362 at the optimal concentration 1μmol/L for 4,12,24,36,and 48hours, compared with time 0hour ,there was a significant difference between the relative expression levels(rER) of FasL mRNA at time point 12,24,36,36, and 48hour (p<0.05) , Compared with time point 24 hour, no significant difference was found at time point 36,48 hour (p>0.05).⑶CpG-ODN could downregulate the expression of FasL in HeLa and Jurkat cell, but had no effect on the expression of Fas. After incubation with CpG-ODN at concentration of 1μmol/L for 24hours,the rERs of FasL mRNA in HeLa and Jurkat cell were downregulated, and the decrease was statistically significant(p<0.05),and the changes of rERs of Fas mRNA in HeLa and Jurkat cell were statistically in significant(p>0.05).⑷CpG-ODN could decrease the apoptosis of Jurkat cells induced by HeLa cells. After treatment with CpG-ODN,the apoptosis rate of Jurkat T cells induced by HeLa cells pretreated with CpG-ODN was (6.41±2.81)%, and that of Jurkat T cells induced by HeLa cells without CpG-ODN pretreatment is (29.23±6.85)%,the difference was statistically significant(p<0.05).Conclusions CpG-ODN functions in a dose and time dependent mannar and CpG-ODN can induce downregulation of expression FasL mRNA in HeLa and Jurkat cells. HeLa cells might evade the immune surveillance though expression of FasL to induce apoptosis of T lymphocytes, and the role of CpG-ODN is to down-regulate the expression of FasL in order to decrease the induction of apoptosis through the FasL-Fas pathway.
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