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

Mucosal Immunol. 2018 Mar;11(2):462-473. doi: 10.1038/mi.2017.60. Epub 2017 Jul 26.

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-1hiCTLA-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.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Antigens, Bacterial / immunology
  • CD4-Positive T-Lymphocytes / immunology*
  • Cell Communication
  • Cell Movement
  • Cells, Cultured
  • Granuloma, Respiratory Tract / immunology*
  • Humans
  • Immune Evasion
  • Immunity, Cellular
  • Lung / immunology*
  • Lung / microbiology
  • Macaca mulatta / immunology*
  • Macaca mulatta / microbiology
  • Macrophages, Alveolar / immunology*
  • Mice
  • Mice, Inbred C57BL
  • Mycobacterium tuberculosis / physiology*
  • Receptors, CXCR3 / metabolism
  • Tuberculosis / immunology*

Substances

  • Antigens, Bacterial
  • Cxcr3 protein, mouse
  • Receptors, CXCR3