Defective positioning in granulomas but not lung-homing limits CD4 T-cell interactions with Mycobacterium tuberculosis-infected macrophages in rhesus macaques

KD Kauffman, MA Sallin, S Sakai, O Kamenyeva… - Mucosal …, 2018 - nature.com
KD Kauffman, MA Sallin, S Sakai, O Kamenyeva, J Kabat, D Weiner, M Sutphin, D Schimel…
Mucosal immunology, 2018nature.com
Abstract Protection against Mycobacterium tuberculosis (Mtb) infection requires CD4 T cells
to migrate into the lung and interact with infected macrophages. In mice, less-differentiated
CXCR3+ CD4 T cells migrate into the lung and suppress growth of Mtb, whereas CX3CR1+
terminally differentiated Th1 cells accumulate in the blood vasculature and do not control
pulmonary infection. Here we examine CD4 T-cell differentiation and lung homing during
primary Mtb infection of rhesus macaques. Mtb-specific CD4 T cells simultaneously …
Abstract
Protection against Mycobacterium tuberculosis (Mtb) infection requires CD4 T cells to migrate into the lung and interact with infected macrophages. In mice, less-differentiated CXCR3+ CD4 T cells migrate into the lung and suppress growth of Mtb, whereas CX3CR1+ terminally differentiated Th1 cells accumulate in the blood vasculature and do not control pulmonary infection. Here we examine CD4 T-cell differentiation and lung homing during primary Mtb infection of rhesus macaques. Mtb-specific CD4 T cells simultaneously appeared in the airways and blood∼ 21–28 days post exposure, indicating that recently primed effectors are quickly recruited into the lungs after entering circulation. Mtb-specific CD4 T cells in granulomas display a tissue-parenchymal CXCR3+ CX3CR1− PD-1 hi CTLA-4+ phenotype. However, most granuloma CD4 T cells are found within the outer lymphocyte cuff and few localize to the myeloid cell core containing the bacilli. Using the intravascular stain approach, we find essentially all Mtb-specific CD4 T cells in granulomas have extravasated across the vascular endothelium into the parenchyma. Therefore, it is unlikely to be that lung-homing defects introduced by terminal differentiation limit the migration of CD4 T cells into granulomas following primary Mtb infection of macaques. However, intralesional positioning defects within the granuloma may pose a major barrier to T-cell-mediated immunity during tuberculosis.
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