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Cutting edge: major CD8 T cell response to live bacillus Calmette-Guérin is mediated by CD1 molecules

Tetsuo Kawashima1, Yoshihiko Norose, Yoshiyuki Watanabe

  • 1Department of Microbiology and Immunology, Nippon Medical School, Tokyo, Japan.

Journal of Immunology (Baltimore, Md. : 1950)
|May 22, 2003
PubMed

Insights

CD8(+) T cells recognize mycobacteria via CD1 molecules, independent of MHC. These lipid-reactive T cells detect live bacillus Calmette-Guérin (BCG) and produce IFN-gamma, aiding host defense against mycobacterial infections.

Area of Science:

  • Immunology
  • Microbiology
  • Infectious Disease

Background:

  • CD8(+) T cells are vital for defense against mycobacteria in mice, but human responses are challenging to identify.
  • Human group 1 CD1 molecules present mycobacterial lipids to CD8(+) T cells independently of MHC.
  • CD1 molecules' location in the endocytic system aids in monitoring phagosome-resident mycobacteria.

Purpose of the Study:

  • To investigate the role of CD1-restricted CD8(+) T cells in human immune responses to mycobacterial infection.
  • To determine if CD1-dependent CD8(+) T cells can recognize bacillus Calmette-Guérin (BCG) in humans.

Main Methods:

  • Analysis of circulating CD8(+) T cells from BCG-immunized subjects.
  • Assessment of T cell recognition of BCG-infected dendritic cells (DCs).
  • Evaluation of CD1 and MHC dependency of T cell responses.
  • Measurement of IFN-gamma production by T cells.

Main Results:

  • A significant pool of circulating CD8(+) T cells recognizing BCG-infected DCs was found in BCG-immunized individuals.
  • This recognition was CD1-dependent and MHC-independent.
  • These CD1-restricted T cells preferentially detected live BCG and produced IFN-gamma.

Conclusions:

  • Lipid-reactive CD8(+) T cells, restricted by CD1 molecules, represent a significant component of the human immune response to mycobacteria.
  • These T cells contribute to host defense by detecting live mycobacteria and producing protective cytokines like IFN-gamma.

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