Kim Won-Hee, Shin Eun-Hee, Kim Jae-Lip, Yu Seung-Young, Jung Bong-Kwang, Chai Jong-Yil
Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, Seoul, Korea.
Korean J Parasitol. 2010 Dec;48(4):325-9. doi: 10.3347/kjp.2010.48.4.325. Epub 2010 Dec 16.
Toxoplasma gondii KI-1, a recent new isolate from Korea, shows similar pathogenicity and infectivity to mice compared to the virulent RH strain. To understand characteristics of host immunity, including immune enhancement or suppression, we investigated proliferative responses and phenotypes of spleen cells. In addition, kinetics of IFN-γ, a Th1 cytokine, was examined in BALB/c mice up to day 6 post-infection (PI). Intraperitoneal injection of mice with 10(3) KI-1 tachyzoites induced significant decreases (P < 0.05) in proliferative responses of spleen cells. This occurred at days 2-6 PI even when concanavalin A (con A) was added and when stimulated with KI-1 antigen, suggesting suppression of the immunity. CD4(+) T-cells decreased markedly at day 2 PI (P < 0.05), whereas CD8(+) T-cells, NK cells, and macrophages did not show significant changes, except a slight, but significant, increase of CD8(+) T-cells at day 6 PI. The capacity of splenocytes to produce IFN-γ by con A stimulation dropped significantly at days 2-6 PI. These results demonstrate that intraperitoneal injection of KI-1 tachyzoites can induce immunosuppression during the early stage of infection, as revealed by the decrease of CD4(+) T-cells and IFN-γ.
刚地弓形虫KI-1是最近从韩国分离出的新菌株，与强毒株RH相比，它对小鼠表现出相似的致病性和感染性。为了解宿主免疫的特征，包括免疫增强或抑制，我们研究了脾细胞的增殖反应和表型。此外，还检测了BALB/c小鼠感染后6天内Th1细胞因子IFN-γ的动力学变化。给小鼠腹腔注射10³个KI-1速殖子可导致脾细胞增殖反应显著降低（P<0.05）。这种情况在感染后第2至6天出现，即使添加了刀豆蛋白A（con A）并受到KI-1抗原刺激时也是如此，提示免疫受到抑制。感染后第2天CD4⁺T细胞显著减少（P<0.05），而CD8⁺T细胞、NK细胞和巨噬细胞没有显著变化，不过感染后第6天CD8⁺T细胞有轻微但显著的增加。在感染后第2至6天，脾细胞经con A刺激产生IFN-γ的能力显著下降。这些结果表明，腹腔注射KI-1速殖子可在感染早期诱导免疫抑制，这可通过CD4⁺T细胞和IFN-γ的减少得以体现。
