A mycolic acid-specific CD1-restricted T cell population contributes to acute and memory immune responses in human tuberculosis infection

J Clin Invest. 2011 Jun;121(6):2493-503. doi: 10.1172/JCI46216. Epub 2011 May 16.

Abstract

Current tuberculosis (TB) vaccine strategies are largely aimed at activating conventional T cell responses to mycobacterial protein antigens. However, the lipid-rich cell wall of Mycobacterium tuberculosis (M. tuberculosis) is essential for pathogenicity and provides targets for unconventional T cell recognition. Group 1 CD1-restricted T cells recognize mycobacterial lipids, but their function in human TB is unclear and their ability to establish memory is unknown. Here, we characterized T cells specific for mycolic acid (MA), the predominant mycobacterial cell wall lipid and key virulence factor, in patients with active TB infection. MA-specific T cells were predominant in TB patients at diagnosis, but were absent in uninfected bacillus Calmette-Guérin-vaccinated (BCG-vaccinated) controls. These T cells were CD1b restricted, detectable in blood and disease sites, produced both IFN-γ and IL-2, and exhibited effector and central memory phenotypes. MA-specific responses contracted markedly with declining pathogen burden and, in patients followed longitudinally, exhibited recall expansion upon antigen reencounter in vitro long after successful treatment, indicative of lipid-specific immunological memory. T cell recognition of MA is therefore a significant component of the acute adaptive and memory immune response in TB, suggesting that mycobacterial lipids may be promising targets for improved TB vaccines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Adaptive Immunity
  • Adult
  • Aged
  • Antigens, Bacterial / immunology*
  • Antigens, CD1 / immunology*
  • Antitubercular Agents / therapeutic use
  • BCG Vaccine / immunology
  • Cell Wall / immunology*
  • Cells, Cultured / immunology
  • Female
  • Humans
  • Immunologic Memory / immunology*
  • Interferon-gamma / metabolism
  • Interleukin-2 / metabolism
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / immunology*
  • Mycobacterium tuberculosis / pathogenicity
  • Mycolic Acids / immunology*
  • T-Cell Antigen Receptor Specificity*
  • T-Lymphocyte Subsets / immunology*
  • T-Lymphocyte Subsets / metabolism
  • Tuberculosis / drug therapy
  • Tuberculosis / immunology*
  • Tuberculosis / prevention & control
  • Tuberculosis Vaccines
  • Virulence
  • Young Adult

Substances

  • Antigens, Bacterial
  • Antigens, CD1
  • Antitubercular Agents
  • BCG Vaccine
  • Interleukin-2
  • Mycolic Acids
  • Tuberculosis Vaccines
  • Interferon-gamma