小鼠感染不同毒力疟原虫早期根治性治疗对再感染树突状细胞成熟及功能的影响

Radical treatment in the early phase of primary infection with Plasmodium parasites with different levels of virulence and its effect on the maturation and functioning of dendritic cells during the course of reinfection

目的探讨小鼠感染不同毒力疟原虫早期根治性治疗对再感染过程中树突状细胞（DC）成熟及功能的影响。方法分别用两种毒力不同的约氏疟原虫感染DBA/2小鼠,3 d后进行根治性治疗,并于初次感染后90 d进行再感染。通过姬姆萨薄血膜染色法计数红细胞感染率,流式细胞术检测再感染前后不同时间点脾细胞表达MHC-Ⅱ、CD80、CD86和CD40的DC以及活化性T细胞的百分率。结果再感染同种疟原虫后,两组根治性治疗小鼠均出现短暂的低水平虫体血症,再感染后第3 d表达MHC-Ⅱ、CD80、CD86和CD40的DC百分率显著升高（P〈0.01）,再感染后第1~5 d活化性T细胞百分率持续升高（P〈0.05或〈0.01）,但在每一相同检测时间点两组小鼠的虫体血症水平、活化性T细胞和表达MHC-Ⅱ、CD80、CD86、CD40的DC百分率差异均无统计学意义（P〉0.05）。结论小鼠感染不同毒力疟原虫早期根治性治疗后,再感染同种疟原虫,强毒株原虫与弱毒株均能诱导DC成熟并发挥其功能。

Objective To investigate radical treatment in the early phase of primary infection with Plasmodium parasites with different levels of virulence and its effect on maturation and functioning of dendritic cells （DC） during the course of reinfection. Methods DBA/2 mice were infected respectively with Plasmodium yoelii 17XL and P. yoelii 17XNL and radically treated on day 3 after infection. The mice were then respectively reinfected with homologous Plasmodiurn on day 90 after primary infection. The level of parasitemia was observed by means of Giemsa staining of thin blood smears, and flow cytometry was used to quantitatively analyze the percentage of MHC-II ＋ DC, CD80＋ DC, CD86＋ DC, CD40＋ DC, and activated T cells in spleen cells on days 0, 1, 3, and 5 post-reinfection, respectively. Results Parasitemia in radically treated mice was transient after reinfection and extremely low in the two groups of treated mice. The percentage of MHC-II ＋ DC, CD80＋ DC, CD86＋ DC, and CD40＋ DC in spleen cells of the mice all began to increase on day 3 post-reinfection. Moreover, the percentage of activated T cells began to increase steadily from day 1 to day 5 after reinfection. At each time tested, however, the levels of parasitemia and percentage of activated T cells, MHC-II ＋ DC, CD80＋ DC, CD86＋ DC, and CD40＋ DC in spleen cells in the two groups of treated mice did not differ significantly. Conclusion After radical treatment in the early phase of primary infection with Plasmodium parasites with different levels of virulence, a second challenge with virulent plasmodium caused DC to mature and function, much as a less virulent Plasmodiurn infection would.