Ruminant Diseases and Immunology Research Unit, National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, IA 50010;
J Immunol. 2014 Mar 15;192(6):2756-69. doi: 10.4049/jimmunol.1302567. Epub 2014 Feb 14.
Promoting effective immunity to Mycobacterium bovis infection is a challenge that is of interest to the fields of human and animal medicine alike. We report that γδ T cells from virulent M. bovis-infected cattle respond specifically and directly to complex, protein, and nonprotein mycobacterial Ags. Importantly, to our knowledge, we demonstrate for the first time that bovine γδ T cells specifically recognize peptide Ags derived from the mycobacterial protein complex ESAT6:CFP10 and that this recognition requires direct contact with APCs and signaling through the T cell Ag receptor but is independent of MHC class I or II. Furthermore, we show that M. bovis infection in cattle induces robust IL-17A protein responses. Interestingly, in contrast to results from mice, bovine CD4 T cells, and not γδ T cells, are the predominant source of this critical proinflammatory mediator. Bovine γδ T cells are divided into subsets based upon their expression of Workshop Cluster 1 (WC1), and we demonstrate that the M. bovis-specific γδ T cell response is composed of a heterogeneous mix of WC1-expressing populations, with the serologically defined WC1.1(+) and WC1.2(+) subsets responding in vitro to mycobacterial Ags and accumulating in the lesions of M. bovis-infected animals. The results described in this article enhance our understanding of γδ T cell biology and, because virulent M. bovis infection of cattle represents an excellent model of tuberculosis in humans, contribute to our overall understanding of the role of γδ T cells in the mycobacterial-specific immune response.
促进对牛分枝杆菌感染的有效免疫是人类和动物医学领域都感兴趣的挑战。我们报告说,来自毒力牛分枝杆菌感染牛的 γδ T 细胞特异性且直接地对复杂的、蛋白质和非蛋白质的分枝杆菌抗原作出反应。重要的是,据我们所知,我们首次证明牛 γδ T 细胞特异性识别源自分枝杆菌蛋白复合物 ESAT6:CFP10 的肽抗原,并且这种识别需要与 APC 的直接接触和 T 细胞抗原受体的信号传导,但不依赖于 MHC Ⅰ类或Ⅱ类。此外,我们表明牛分枝杆菌感染在牛中诱导强烈的 IL-17A 蛋白反应。有趣的是,与来自小鼠的结果相反,牛 CD4 T 细胞而不是 γδ T 细胞是这种关键促炎介质的主要来源。牛 γδ T 细胞根据其对 Workshop Cluster 1(WC1)的表达分为亚群,我们证明牛分枝杆菌特异性 γδ T 细胞反应由一组异质的 WC1 表达群体组成,血清学定义的 WC1.1(+)和 WC1.2(+)亚群在体外对分枝杆菌抗原作出反应,并在牛分枝杆菌感染动物的病变中积累。本文所述的结果增强了我们对 γδ T 细胞生物学的理解,并且因为牛分枝杆菌的毒力感染代表了人类结核病的极佳模型,因此有助于我们全面了解 γδ T 细胞在分枝杆菌特异性免疫反应中的作用。