38 000 MW antigen-specific major histocompatibility complex class I restricted interferon-gamma-secreting CD8+ T cells in healthy contacts of tuberculosis

Immunology. 1998 Dec;95(4):585-90. doi: 10.1046/j.1365-2567.1998.00648.x.


CD8+ T lymphocytes are required to protect mice against Mycobacterium tuberculosis, although in early infection the mechanism appears not to be via perforin or granzyme-mediated lysis of the infected target, and may be via interferon-gamma (IFN-gamma) production. We therefore investigated whether CD8+ T cells specific for the immunoprotective 38 000 MW antigen of M. tuberculosis could be detected in infected humans. Using a recombinant vaccinia virus expressing the 38 000 MW antigen of M. tuberculosis (rV38) and a control vaccinia virus (rVras) we demonstrated that both viruses stimulated IFN-gamma production from freshly isolated peripheral blood mononuclear cells (PBMC) in a 36-hr enzyme-linked immunospot assay. Cell depletion and antibody blockade established that the bulk of the 38 000 MW antigen-specific IFN-gamma response was mediated by CD8+, major histocompatibility complex class I-restricted T cells, whereas the anti-vaccinia virus response was predominantly mediated by CD4+ T cells. In further evaluations PBMC from all seven healthy tuberculosis-exposed contacts had a 38 000 MW antigen-specific IFN-gamma response, whereas seven patients with untreated sputum-positive pulmonary tuberculosis had very low levels of 38 000 antigen-specific IFN-gamma-producing cells. These preliminary observations demonstrate the utility of recombinant vaccinia viruses in restimulating freshly isolated CD4+ and CD8+ T cells. The bias towards a higher frequency of IFN-gamma-producing CD8+ T cells in contacts rather than patients may indicate a protective role for CD8+ cells in human tuberculosis.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antigens, Bacterial / administration & dosage*
  • Antigens, Bacterial / immunology
  • CD8-Positive T-Lymphocytes / immunology*
  • Cells, Cultured
  • Enzyme-Linked Immunosorbent Assay / methods
  • Female
  • Humans
  • Interferon-gamma / analysis
  • Interferon-gamma / metabolism*
  • Male
  • Middle Aged
  • Molecular Weight
  • Mycobacterium tuberculosis / immunology*
  • Tuberculosis / immunology*
  • Tuberculosis / transmission
  • Vaccines, Synthetic / administration & dosage
  • Vaccinia / immunology
  • Viral Vaccines / administration & dosage


  • Antigens, Bacterial
  • Vaccines, Synthetic
  • Viral Vaccines
  • Interferon-gamma