CD4~+CD25~+调节性T细胞在约氏疟原虫感染小鼠应答早期中的作用

目的探讨CD4+CD25+调节性T细胞在约氏疟原虫感染早期的作用及意义。方法用约氏疟原虫(致死型)感染DBA/2和BALB/c小鼠,计数红细胞感染率;在感染后第0d、3d、4d、5d和6d提取脾细胞应为,流式细胞术检测两种小鼠感染不同时间脾细胞悬液中CD4+T细胞和CD4+CD25+T细胞百分含量;ELISA法检测脾细胞培养上清IFNγ、IL10和TGFβ1水平。结果DBA/2小鼠的IFNγ水平在感染后第3d迅速升高后缓慢下降(P<0.01),CD4+CD25+T细胞数仅在感染后第5d出现有意义的升高(P<0.05),而IL10水平和CD4+T细胞数量都无明显改变。BALB/c小鼠的IFNγ水平在感染后第3d出现有意义的升高后迅速下降(P<0.01),CD4+CD25+T细胞数在感染后第3d开始明显升高,于感染后第5d出现下降(P<0.05),而IL10水平自感染后第3～6d持续维持高水平(P<0.05),CD4+T细胞数量于感染后第6天明显下降(P<0.05)。结论CD4+CD25+调节性T细胞在致死型约氏疟原虫感染BALB/c小鼠早期可能通过抑制性细胞因子IL10发挥免疫抑制作用。

Role of CD4+CD25+regulatory T cells in early response against Plasmodium yoelii infection

To investigate the role and significance of CD4~ +CD25~ +regulatory T cells during early infection of Plasmodium yoelii. DBA/2 and BALB/c mice were infected by i.p. injection of P. yoelii17XL parasitized erythrocytes. Parasitemia of individual mice was monitored by the microscopic examination of blood smear stained with Giemsa. Mice from normal and infected groups were sacrificed on 0,3 and 6 days post-infection for collection of spleen cells. Applying flow cytometry to quantitatively analyze CD4~ + T cells and CD4~ +CD25~ +T cells, levels of IFN-γ、IL-10 and TGF-β1 in spleen supernatants were measured by ELISA kits. It was found that the levels of IFN-γ increased rapidly at day 3 post-infection and then decreased slowly in DBA/2 mice, the proportion of CD4~ +CD25~ +T lymphocytes increased significantly only at day 5. However there was no change about IL-10 and CD4~ + T cells. The levels of IFN-γ increased significantly and peaked at day 3, which was followed by a sharp reduction in BALB/c mice, the proportion of CD4~ +CD25~ +T lymphocytes increased obviously at day 3(P<0.05)and then decreased sharply, the levels of IL-10 increased rapidly and were kept at elevated levels from day 3 to day 6(P<0.05) and the number of CD4~ + T cells decreased at day 6 compared with DBA/2 mice. These results indicate that CD4~ +CD25~ +regulatory T cells perhaps are mainly involved in the suppression by means of IL-10 during early infection of lethal strain of Plasmodium yoelii in BALB/c mice.