Department of Infectious Diseases, Leiden University Medical Center, Leiden 2333 ZA, The Netherlands.
J Immunol. 2011 Aug 1;187(3):1393-402. doi: 10.4049/jimmunol.1100980. Epub 2011 Jun 24.
MHC class I-restricted CD8(+) T cells play an important role in protective immunity against mycobacteria. Previously, we showed that p113-121, derived from Mycobacterium leprae protein ML1419c, induced significant IFN-γ production by CD8(+) T cells in 90% of paucibacillary leprosy patients and in 80% of multibacillary patients' contacts, demonstrating induction of M. leprae-specific CD8(+) T cell immunity. In this work, we studied the in vivo role and functional profile of ML1419c p113-121-induced T cells in HLA-A0201 transgenic mice. Immunization with 9mer or 30mer covering the p113-121 sequence combined with TLR9 agonist CpG induced HLA-A0201-restricted, M. leprae-specific CD8(+) T cells as visualized by p113-121/HLA-A0201 tetramers. Most CD8(+) T cells produced IFN-γ, but distinct IFN-γ(+)/TNF-α(+) populations were detected simultaneously with significant secretion of CXCL10/IFN-γ-induced protein 10, CXCL9/MIG, and VEGF. Strikingly, peptide immunization also induced high ML1419c-specific IgG levels, strongly suggesting that peptide-specific CD8(+) T cells provide help to B cells in vivo, as CD4(+) T cells were undetectable. An additional important characteristic of p113-121-specific CD8(+) T cells was their capacity for in vivo killing of p113-121-labeled, HLA-A0201(+) splenocytes. The cytotoxic function of p113-121/HLA-A*0201-specific CD8(+) T cells extended into direct killing of splenocytes infected with live Mycobacterium smegmatis expressing ML1419c: both 9mer and 30mer induced CD8(+) T cells that reduced the number of ML1419c-expressing mycobacteria by 95%, whereas no reduction occurred using wild-type M. smegmatis. These data, combined with previous observations in Brazilian cohorts, show that ML1419c p113-121 induces potent CD8(+) T cells that provide protective immunity against M. leprae and B cell help for induction of specific IgG, suggesting its potential use in diagnostics and as a subunit (vaccine) for M. leprae infection.
MHC Ⅰ类限制性 CD8(+) T 细胞在抗分枝杆菌的保护性免疫中发挥重要作用。先前，我们发现来自麻风分枝杆菌蛋白 ML1419c 的 p113-121 可诱导 90%的少菌型麻风病患者和 80%的多菌型患者接触者的 CD8(+) T 细胞产生显著的 IFN-γ，表明诱导了麻风分枝杆菌特异性 CD8(+) T 细胞免疫。在这项工作中，我们研究了 ML1419c p113-121 诱导的 T 细胞在 HLA-A0201 转基因小鼠体内的作用和功能特征。用覆盖 p113-121 序列的 9mer 或 30mer 与 TLR9 激动剂 CpG 联合免疫，可诱导 HLA-A0201 限制性、麻风分枝杆菌特异性 CD8(+) T 细胞，如 p113-121/HLA-A0201 四聚体所示。大多数 CD8(+) T 细胞产生 IFN-γ，但同时也检测到不同的 IFN-γ(+)/TNF-α(+)群体，同时显著分泌 CXCL10/IFN-γ 诱导蛋白 10、CXCL9/MIG 和 VEGF。引人注目的是，肽免疫还诱导了高 ML1419c 特异性 IgG 水平，强烈表明 CD8(+) T 细胞在体内为 B 细胞提供帮助，因为未检测到 CD4(+) T 细胞。p113-121 特异性 CD8(+) T 细胞的另一个重要特征是其体内杀伤 p113-121 标记的 HLA-A0201(+) 脾细胞的能力。p113-121/HLA-A*0201 特异性 CD8(+) T 细胞的细胞毒性作用扩展到直接杀伤表达 ML1419c 的活耻垢分枝杆菌感染的脾细胞：9mer 和 30mer 都诱导了 CD8(+) T 细胞，使表达 ML1419c 的分枝杆菌数量减少了 95%，而使用野生型耻垢分枝杆菌则没有减少。这些数据与巴西队列的先前观察结果相结合，表明 ML1419c p113-121 诱导了有效的 CD8(+) T 细胞，为麻风分枝杆菌提供了保护性免疫，并为诱导特异性 IgG 提供了 B 细胞帮助，提示其在麻风分枝杆菌感染的诊断和作为亚单位（疫苗）中的潜在用途。
