实验观察伯氏疟原虫再感染对免疫记忆形成的影响

Experimental observation of the effects of reinfection with Plasmodium berghei ANKA on formation of immune memory

目的探讨疟疾再感染对免疫记忆形成的影响。方法用伯氏疟原虫感染DBA/2小鼠,感染后3 d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(0 d)和再感染后(1、3、5 d)不同时间点脾细胞中记忆性T细胞和记忆性B细胞百分率。结果再感染前小鼠脾细胞中记忆性T、B细胞百分率均略高于正常鼠;再感染后,小鼠仅出现短暂的低水平原虫血症,记忆性T、B细胞百分率分别于再感染后第1 d和第3 d较对照组显著升高(P<0.01),但再感染后第5出现一定程度的下降。结论疟疾再感染可促进免疫记忆的产生,但高水平的免疫记忆不能持久存在。

Objective To investigate the effects of malaria reinfection on formation of immune memory.Methods DBA/2 mice were infected with Plasmodium berghei ANKA-parasitized erythrocytes and radically treated with chloroquine plus artesunate on day 3 after infection.Then the mice were reinfected with P.berghei ANKA on day 90 after primary infection.The level of parasitemia during primary and secondary infections was observed by means of the Giemsa staining of thin blood smears,and flow cytometry was used to quantitatively analyze the percentage of memory T cells and memory B cells in the spleen cell population on days 0,1,3,and 5 post-reinfection.Results Parasitemia in mice post-reinfection was transient and extremely mild,although the percentage of memory T cells and memory B cells in the spleen cell population from the mice began to increase on day 1 and day 3 post-reinfection,respectively.Both began to decline to a degree on day 5 post-reinfection.Moreover,the percentage of memory T cells and memory B cells in pre-reinfection mice was slightly higher than that in control（noninfected） mice.Conclusion Malaria reinfection can promote the generation of immune memory,but high levels of immune memory are not sustained.