Genome-based in silico identification of new Mycobacterium tuberculosis antigens activating polyfunctional CD8+ T cells in human tuberculosis

J Immunol. 2011 Jan 15;186(2):1068-80. doi: 10.4049/jimmunol.1002212. Epub 2010 Dec 17.

Abstract

Although CD8(+) T cells help control Mycobacterium tuberculosis infection, their M. tuberculosis Ag repertoire, in vivo frequency, and functionality in human tuberculosis (TB) remains largely undefined. We have performed genome-based bioinformatics searches to identify new M. tuberculosis epitopes presented by major HLA class I supertypes A2, A3, and B7 (covering 80% of the human population). A total of 432 M. tuberculosis peptides predicted to bind to HLA-A*0201, HLA-A*0301, and HLA-B*0702 (representing the above supertypes) were synthesized and HLA-binding affinities determined. Peptide-specific CD8(+) T cell proliferation assays (CFSE dilution) in 41 M. tuberculosis-responsive donors identified 70 new M. tuberculosis epitopes. Using HLA/peptide tetramers for the 18 most prominently recognized HLA-A*0201-binding M. tuberculosis peptides, recognition by cured TB patients' CD8(+) T cells was validated for all 18 epitopes. Intracellular cytokine staining for IFN-γ, IL-2, and TNF-α revealed mono-, dual-, as well as triple-positive CD8(+) T cells, indicating these M. tuberculosis peptide-specific CD8(+) T cells were (poly)functional. Moreover, these T cells were primed during natural infection, because they were absent from M. tuberculosis-noninfected individuals. Control CMV peptide/HLA-A*0201 tetramers stained CD8(+) T cells in M. tuberculosis-infected and noninfected individuals equally, whereas Ebola peptide/HLA-A*0201 tetramers were negative. In conclusion, the M. tuberculosis-epitope/Ag repertoire for human CD8(+) T cells is much broader than hitherto suspected, and the newly identified M. tuberculosis Ags are recognized by (poly)functional CD8(+) T cells during control of infection. These results impact on TB-vaccine design and biomarker identification.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antigens, Bacterial / genetics*
  • Antigens, Bacterial / metabolism
  • Antigens, Bacterial / physiology
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / microbiology*
  • Computational Biology
  • Epitopes, T-Lymphocyte / genetics
  • Epitopes, T-Lymphocyte / metabolism
  • Epitopes, T-Lymphocyte / physiology
  • Female
  • Genome, Bacterial*
  • Genome, Human
  • Humans
  • Intracellular Fluid / immunology
  • Intracellular Fluid / metabolism
  • Intracellular Fluid / microbiology
  • Lymphocyte Activation / genetics
  • Lymphocyte Activation / immunology*
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / immunology*
  • Predictive Value of Tests
  • Tuberculosis / genetics
  • Tuberculosis / immunology*
  • Tuberculosis / metabolism*

Substances

  • Antigens, Bacterial
  • Epitopes, T-Lymphocyte