CD4^+CD25^+调节性T细胞对疟原虫感染鼠结局的影响

Effect of CD4^+CD25^+ regulatory T cell on infective outcome of mice infected with plasmodium

目的探讨CD4+CD25+调节性T细胞与疟原虫感染鼠结局的相关性。方法分别以致死型约氏疟原虫(Plasmodium yoelii17XL)和夏氏疟原虫(Plasmodium chabaudi chabaudi AS)感染BALB/c小鼠,制备薄血膜,Giemsa染色,镜检计数红细胞感染率;以流式细胞术检测脾细胞悬液中CD4+CD25+T细胞百分率。结果P.yoelii17XL感染鼠的原虫血症于感染后第6 d达到峰值水平(55.5%),并于当日和次日内全部死亡,CD4+CD25+T细胞水平于感染后第1 d迅速升高,且于感染后第5 d达到峰值水平(23.6%);P.c.chabaudiAS感染鼠的原虫血症在感染后第8 d达到峰值水平(38.2%)后迅速下降,并于感染后第15 d左右全部自愈,CD4+CD25+T细胞水平也于感染后第1 d开始升高,但其感染后第5 d的峰值水平(13.8%)显著低于P.yoelii17XL感染小鼠(P<0.01)。结论CD4+CD25+T细胞活化水平可显著影响疟原虫感染鼠的结局。

Objective To explore the effect of CD4^＋ CD25^＋ regulatory T cell on infective outcome of mice infected with plasmodium. Methods BALB/c mice were infected by i. p. injection of Plasrnodium yoelli 17XL or Plasrnodiurn chabaudi chabaudi AS parasitized RBC. Parasitemia of individual mice was monitored by the microscopic examination on, blood smears stained with Giemsa, and the percentage of CD4^＋ CD25^＋ T cell in splenocytes were detected by flow cytometry. Results Parasitemia of mice infected with P. yoelii 17XL reached a peak level （55.5%） on day 6 post-infection, then all mice died within two days. Their percentage of CD4^＋ CD25^＋ T cell in splenocytes started rising on day 1 post-infection and reached a peak level（23.6%） on day 5 post infection. Parasitemia of mice infected with P. c. chabaudi AS reached a peak level （38.2%） on day 8 post-infection, then it declined rapidly, and all mice spontaneously recovered on day 15 post-infection. Percentage of CD4^＋ CD25^＋ T cell in splenocytes of mice infected with P. c. chabaudi AS started also rising on day 1 post-infection, but their peak level（13.8 %）on day 5 post-infection was obviously lower than that of mice infected with P. yoelii 17XL. Conclusion Active degree of CD4^＋ CD25^＋ T cell may markedly affect the infective outcome of mice infected with plasmodium.