Specific recognition of mycobacterial protein and peptide antigens by γδ T cell subsets following infection with virulent Mycobacterium bovis

J Immunol. 2014 Mar 15;192(6):2756-69. doi: 10.4049/jimmunol.1302567. Epub 2014 Feb 14.

Abstract

Promoting effective immunity to Mycobacterium bovis infection is a challenge that is of interest to the fields of human and animal medicine alike. We report that γδ T cells from virulent M. bovis-infected cattle respond specifically and directly to complex, protein, and nonprotein mycobacterial Ags. Importantly, to our knowledge, we demonstrate for the first time that bovine γδ T cells specifically recognize peptide Ags derived from the mycobacterial protein complex ESAT6:CFP10 and that this recognition requires direct contact with APCs and signaling through the T cell Ag receptor but is independent of MHC class I or II. Furthermore, we show that M. bovis infection in cattle induces robust IL-17A protein responses. Interestingly, in contrast to results from mice, bovine CD4 T cells, and not γδ T cells, are the predominant source of this critical proinflammatory mediator. Bovine γδ T cells are divided into subsets based upon their expression of Workshop Cluster 1 (WC1), and we demonstrate that the M. bovis-specific γδ T cell response is composed of a heterogeneous mix of WC1-expressing populations, with the serologically defined WC1.1(+) and WC1.2(+) subsets responding in vitro to mycobacterial Ags and accumulating in the lesions of M. bovis-infected animals. The results described in this article enhance our understanding of γδ T cell biology and, because virulent M. bovis infection of cattle represents an excellent model of tuberculosis in humans, contribute to our overall understanding of the role of γδ T cells in the mycobacterial-specific immune response.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antigens, Bacterial / immunology*
  • Antigens, Bacterial / metabolism
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • Cattle
  • Cells, Cultured
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Humans
  • Interferon-gamma / immunology
  • Interferon-gamma / metabolism
  • Interleukin-17 / immunology
  • Interleukin-17 / metabolism
  • Lymphocyte Activation / immunology
  • Male
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / immunology
  • Membrane Glycoproteins / metabolism
  • Mycobacterium bovis / immunology*
  • Mycobacterium bovis / pathogenicity
  • Receptors, Antigen, T-Cell, gamma-delta / immunology*
  • Receptors, Antigen, T-Cell, gamma-delta / metabolism
  • Recombinant Fusion Proteins / immunology
  • Recombinant Fusion Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • T-Lymphocyte Subsets / immunology*
  • T-Lymphocyte Subsets / metabolism
  • Tuberculosis, Bovine / immunology*
  • Tuberculosis, Bovine / microbiology
  • Virulence / immunology

Substances

  • Antigens, Bacterial
  • DMBT1 protein, Bos taurus
  • ESAT-6-CFP10 fusion protein
  • Interleukin-17
  • Membrane Glycoproteins
  • Receptors, Antigen, T-Cell, gamma-delta
  • Recombinant Fusion Proteins
  • Interferon-gamma