Human cytolytic and interferon γ-secreting CD8⁺T lymphocytes specific forMycobacterium tuberculosis

Abstract

Protective immunity to Mycobacterium tuberculosis is poorly understood, but mounting evidence, at least in animal models, implicates major histocompatibility complex class I-restricted CD8 ؉ T cells as an essential component. By using a highly sensitive assay for single cell interferon ␥ release, we screened an array of M. tuberculosis antigenderived peptides congruent with HLA class I allele-specific motifs. We identified CD8؉ T cells specific for epitopes in the early secretory antigenic target 6 during active tuberculosis, after clinical recovery and in healthy contacts. Unrestimulated cells exhibited peptide-specific interferon ␥ secretion, whereas lines or clones recognized endogenously processed antigen and showed cytolytic activity. These results provide direct evidence for the involvement of CD8 ؉ cytotoxic T lymphocytes in host defense against M. tuberculosis in humans and support current attempts to generate protective cytotoxic T lymphocyte responses against M. tuberculosis by vaccination.

CD40 Ligand Trimer Enhances the Response of CD8+ T Cells to Mycobacterium tuberculosis

“…Briefly, cells were permeabilized with permeabilization buffer (BD PharMingen) for 30 min on ice, then washed with cell wash buffer (BD PharMingen) and incubated with anti-granulysin mAb, DH4 (18), antiperforin mAb, ␦G9 (Kamiya Biomedical, Seattle, WA) or isotype control mouse IgG1 (BD PharMingen), for 30 min, and then washed three times with cell wash buffer. The cells were then incubated with FITC goat F(abЈ) 2 anti-mouse IgG (Southern Biotechnology Associates, Birmingham, AL) for 30 min on ice. To detect Fas ligand (FasL; CD95), CD8 ϩ T cells were incubated with biotin-labeled anti-CD95 mAb, then with streptavidin-PE (both from BD PharMingen).…”

“…In humans infected with M. tuberculosis, CD8 ϩ T cells produce IFN-␥ in response to mycobacterial Ag, lyse M. tuberculosisinfected target cells (2,3), and can directly kill mycobacteria by secreting granulysin (4,5). Effective immunity against tuberculosis is likely to depend in part on priming and maintenance of Agspecific CD8 ϩ T cells.…”

Cutting Edge: Major CD8 T Cell Response to Live Bacillus Calmette-Guérin Is Mediated by CD1 Molecules

“…Evidence obtained from analysis of TAP-and CD1d-deficient mice as well as an earlier study of mice lacking the expression of ␤ 2 -microglobulin unequivocally demonstrated a significant contribution of MHC class I-restricted CD8 ϩ CTLs in clearing mycobacterial infection in mice (3,4). In humans, the potential role of CD8 ϩ T cells in protection against mycobacterial infection has been appreciated partially by isolating and characterizing mycobacteria-specific, MHC class I-restricted CD8 ϩ T cell lines (5). These studies focused on macrophages, the well-known reservoir for mycobacteria, as CTL target cells, that were either infected with mycobacteria or pulsed with mycobacteria-derived peptide Ags.…”

Profound peripheral T-lymphocyte depletion and activation in disseminated tuberculosis

“…It has been demonstrated that CD 8 + T-lymphocytes have cytolytic activity against the tuberculosis bacillus [12], and their deficiency can result in susceptibility to infection by M. tuberculosis [13]. However, the exact function of these cells in host defense remains controversial.…”