【摘要】 目的探讨地塞米松对约氏疟原虫(Plasmodium yoelii 17XL,P.y17XL)感染DBA/2小鼠早期免疫应答的调节效应机制。方法 6～8周、雌性DBA/2小鼠,随机分为实验组和对照组,经腹腔接种1×106P.yl7XL寄生的红细胞,实验组于感染后第1和2天尾静脉给予地塞米松处理。动态观察各组感染小鼠原虫血症水平和生存率;于感染后第0天、3天和5天分别提取小鼠脾细胞,流式细胞术检测树突状细胞(DCs)亚群(髓样树突与浆样树突)百分比及功能分子的表达,CD4+CD25+Foxp3+T细胞占CD4+T细胞总数的百分比;ELISA法检测脾细胞培养上清中IFN-γ、IL-10的分泌水平;Griess反应检测脾细胞培养上清中一氧化氮(NO)含量。结果与正常感染组相比,地塞米松处理组:①生存率明显降低;②感染后第3和5天脾细胞中两种树突状细胞亚群水平以及DCs表面MHCⅡ类分子和共刺激分子CD86的表达水平显著下降,而CD4+CD25+Foxp3+T细胞仅于感染后第3天降低,而第5天之后则明显升高;③脾细胞培养上清中IFN-γ、IL-10、NO的产生水平均明显降低。结论地塞米松由于显著抑制DBA/2小鼠抵御P.y17XL感染保护性免疫应答的建立,从而致其死亡。更多还原

【Abstract】 Objective To investigate The effect of dexamethasone on the immune responses during the early stage of Plasmodium yoelii 17XL infection in DBA/2 mice.Methods Female 6–8-week-old DBA/2 mice were randomly divided into two groups.The mice in dexamethasone treated group were administered dexamethasone once a day on days 1 and 2 postinfection(p.i.).Parasitemiaandmortality were monitored.Flow cytometry was introduced to detect the percentages of myeloid DCs,plasmacytoid DCs,surface molecule MHCII or CD80 expressed on spleen DCs,as well asthe percentages of CD4+CD25+Foxp3+T cells in CD4+T cells.The levels of IFN-γ,IL-10 and NO in the supernatant of splenocytes culture were detected by ELISA and Griess reaction,respectively.Results Compared with the cntrolgroup,thedexamethasone treated groupshowed that: ①lower survivaltime;②on days 3 and 5p.i.the percentages of myeloid DCs,plasmacytoid DCs,surface molecule MHCII or CD86 expressed on spleen DCs all decreased significantly;the percentages of CD4+CD25+Foxp3+T cells in CD4+T cells only declined on day 3 p.i.,but increased after day 5;③IL-10、IFN-γ and NO all risedremarkably.Conclusions Pretreatment with dexamethasonesignificantly suppressed Th1 immune response during the early stage of P.y17XL infection in DBA/2mice leading to their death.更多还原