Universidade Federal da Bahia, Salvador, Brazil.
Rega Institute for Medical Research, Department of Microbiology and Immunology, KU Leuven, Belgium
J Invest Dermatol. 2013 Jun;133(6):1533-40. doi: 10.1038/jid.2013.4. Epub 2013 Jan 15.
A protective or deleterious role of CD8(+)T cells in human cutaneous leishmaniasis (CL) has been debated. The present report explores the participation of CD8(+)T cells in disease pathogenesis as well as in parasite killing. CD8(+)T cells accumulated in CL lesions as suggested by a higher frequency of CD8(+)CD45RO(+)T cells and CD8(+)CLA(+)T cells compared with peripheral blood mononuclear cells. Upon Leishmania braziliensis restimulation, most of the CD8(+)T cells from the lesion expressed cytolytic markers, CD107a and granzyme B. Granzyme B expression in CL lesions positively correlated with lesion size and percentage of TUNEL-positive cells. We also observed a significantly higher percentage of TUNEL-positive cells and granzyme B expression in the biopsies of patients showing a more intense necrotic process. Furthermore, coculture of infected macrophages and CD8(+)T lymphocytes resulted in the release of granzyme B, and the use of granzyme B inhibitor, as well as z-VAD, Fas:Fc, or anti-IFN-γ, had no effect upon parasite killing. However, coculture of infected macrophages with CD4(+)T cells strongly increased parasite killing, which was completely reversed by anti-IFN-γ. Our results reveal a dichotomy in human CL: CD8(+) granzyme B(+)T cells mediate tissue injury, whereas CD4(+)IFN-γ(+)T cells mediate parasite killing.
CD8(+)T 细胞在人类皮肤利什曼病(CL)中的保护或有害作用一直存在争议。本报告探讨了 CD8(+)T 细胞在疾病发病机制以及寄生虫杀伤中的参与。与外周血单核细胞相比,CD8(+)CD45RO(+)T 细胞和 CD8(+)CLA(+)T 细胞的频率更高,表明 CD8(+)T 细胞在 CL 病变中积累。在巴西利什曼原虫再刺激后,来自病变的大多数 CD8(+)T 细胞表达细胞毒性标志物 CD107a 和颗粒酶 B。CL 病变中颗粒酶 B 的表达与病变大小和 TUNEL 阳性细胞的百分比呈正相关。我们还观察到,在坏死过程更强烈的患者的活检中,TUNEL 阳性细胞和颗粒酶 B 的表达明显更高。此外,感染的巨噬细胞和 CD8(+)T 淋巴细胞的共培养导致颗粒酶 B 的释放,并且使用颗粒酶 B 抑制剂以及 z-VAD、Fas:Fc 或抗 IFN-γ 对寄生虫杀伤没有影响。然而,感染的巨噬细胞与 CD4(+)T 细胞的共培养强烈增加了寄生虫的杀伤,而抗 IFN-γ 完全逆转了这一过程。我们的结果揭示了人类 CL 的二分法:CD8(+)颗粒酶 B(+)T 细胞介导组织损伤,而 CD4(+)IFN-γ(+)T 细胞介导寄生虫杀伤。