Departamento de Microbiología, Instituto Nacional de Enfermedades Respiratorias, Mexico City, Mexico.
Immunology. 2013 Jan;138(1):34-46. doi: 10.1111/imm.12010.
Intracellular pathogens, such as Mycobacterium tuberculosis, reside in the phagosomes of macrophages where antigenic processing is initiated. Mycobacterial antigen-MHC class II complexes are formed within the phagosome and are then trafficked to the cell surface. Interferon-γ (IFN-γ) and interleukin-10 (IL-10) influence the outcome of M. tuberculosis infection; however, the role of these cytokines with regard to the formation of M. tuberculosis peptide-MHC-II complexes remains unknown. We analysed the kinetics and subcellular localization of M. tuberculosis peptide-MHC-II complexes in M. tuberculosis-infected human monocyte-derived macrophages (MDMs) using autologous M. tuberculosis-specific CD4(+) T cells. The MDMs were pre-treated with either IFN-γ or IL-10 and infected with M. tuberculosis. Cells were mechanically homogenized, separated on Percoll density gradients and manually fractionated. The fractions were incubated with autologous M. tuberculosis -specific CD4(+) T cells. Our results demonstrated that in MDMs pre-treated with IFN-γ, M. tuberculosis peptide-MHC-II complexes were detected early mainly in the phagosomal fractions, whereas in the absence of IFN-γ, the complexes were detected in the endosomal fractions. In MDMs pre-treated with IL-10, the M. tuberculosis peptide-MHC-II complexes were retained in the endosomal fractions, and these complexes were not detected in the plasma membrane fractions. The results of immunofluorescence microscopy demonstrated the presence of Ag85B associated with HLA-DR at the cell surface only in the IFN-γ-treated MDMs, suggesting that IFN-γ may accelerate M. tuberculosis antigen processing and presentation at the cell membrane, whereas IL-10 favours the trafficking of Ag85B to vesicles that do not contain LAMP-1. Therefore, IFN-γ and IL-10 play a role in the formation and trafficking of M. tuberculosis peptide-MHC-II complexes.
细胞内病原体，如结核分枝杆菌，存在于巨噬细胞的吞噬体中，抗原加工在此处启动。结核分枝杆菌抗原-MHC II 复合物在吞噬体中形成，然后被转运到细胞表面。干扰素-γ (IFN-γ) 和白细胞介素-10 (IL-10) 影响结核分枝杆菌感染的结果；然而，这些细胞因子在结核分枝杆菌肽-MHC II 复合物形成中的作用尚不清楚。我们使用自体结核分枝杆菌特异性 CD4+T 细胞分析了结核分枝杆菌感染的人单核细胞衍生巨噬细胞 (MDM) 中结核分枝杆菌肽-MHC II 复合物的动力学和亚细胞定位。用 IFN-γ 或 IL-10 预处理 MDM ，然后用结核分枝杆菌感染。细胞用机械匀浆，在 Percoll 密度梯度上分离，并手动分馏。将各馏分与自体结核分枝杆菌特异性 CD4+T 细胞孵育。我们的结果表明，在 IFN-γ 预处理的 MDM 中，早期主要在吞噬体部分检测到结核分枝杆菌肽-MHC II 复合物，而在没有 IFN-γ 的情况下，在内体部分检测到复合物。在 IL-10 预处理的 MDM 中，结核分枝杆菌肽-MHC II 复合物保留在内体部分，在质膜部分未检测到复合物。免疫荧光显微镜的结果表明，只有在 IFN-γ 处理的 MDM 中，Ag85B 与 HLA-DR 相关，存在于细胞表面，表明 IFN-γ 可能加速结核分枝杆菌抗原在质膜上的加工和呈递，而 IL-10 有利于 Ag85B 向不包含 LAMP-1 的小泡的转运。因此，IFN-γ 和 IL-10 在结核分枝杆菌肽-MHC II 复合物的形成和转运中发挥作用。
