An exhaustion-like phenotype constrains the activity of CD4+ T cells specific for a self and melanoma antigen

PLoS One. 2015 Apr 15;10(4):e0123332. doi: 10.1371/journal.pone.0123332. eCollection 2015.

Abstract

While the immune system has the capacity to recognize and destroy melanoma, tolerance mechanisms often hinder the development of effective anti-tumor immune responses. Since many melanoma antigens are self proteins expressed in normal melanocytes, self antigen exposure before tumor development can negatively impact the function of T cells specific for these self/tumor antigens. However, the contribution of self tolerance to anti-melanoma T cell dysfunction remains largely unexplored. We have previously described a TCR transgenic (Tg) mouse model in which T cells specific for the self/melanoma antigen, tyrosinase-related protein 1 (TRP1), develop in the presence of endogenous TRP1 expression (Ag+) and diminished antigen presentation due to the absence of gamma-interferon-inducible lysosomal thiol reductase (GILT-/-). We show that TRP1-specific T cells from these Ag+GILT-/-Tg mice do not protect from melanoma tumor growth, fail to induce autoimmune vitiligo, and undergo diminished proliferation compared to T cells from Ag-GILT+/+Tg mice. Despite an increased frequency of TRP1-specific Treg cells in Ag+GILT-/-Tg mice compared to Ag-GILT+/+Tg animals, Treg cell depletion only partially rescues the proliferative capacity of T cells from TRP1-expressing mice, suggesting the involvement of additional suppressive mechanisms. An increased percentage of melanoma-specific T cells from Ag+GILT-/-Tg animals express PD-1, an inhibitory receptor associated with the maintenance of T cell exhaustion. Antibody blockade of PD-1 partially improves the ability of TRP1-specific T cells from Ag+GILT-/-Tg mice to produce IL-2. These findings demonstrate that melanoma-specific T cells exposed to a self/melanoma antigen in healthy tissue develop an exhaustion-like phenotype characterized by PD-1-mediated immunosuppression prior to encounter with tumor.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Neoplasm / immunology*
  • Autoantigens / immunology*
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / metabolism
  • Cell Line, Tumor
  • Cell Proliferation
  • Flow Cytometry
  • Immune Tolerance / immunology
  • Immunophenotyping
  • Interleukin-2 / immunology
  • Interleukin-2 / metabolism
  • Male
  • Melanoma, Experimental / genetics
  • Melanoma, Experimental / immunology
  • Melanoma-Specific Antigens / immunology*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / immunology
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Oxidoreductases / genetics
  • Oxidoreductases / immunology
  • Oxidoreductases Acting on Sulfur Group Donors
  • Programmed Cell Death 1 Receptor / immunology
  • T-Lymphocytes, Regulatory / immunology
  • T-Lymphocytes, Regulatory / metabolism
  • Vitiligo / genetics
  • Vitiligo / immunology

Substances

  • Antigens, Neoplasm
  • Autoantigens
  • Interleukin-2
  • Melanoma-Specific Antigens
  • Membrane Glycoproteins
  • Pdcd1 protein, mouse
  • Programmed Cell Death 1 Receptor
  • Oxidoreductases
  • Tyrp1 protein, mouse
  • Ifi30 protein, mouse
  • Oxidoreductases Acting on Sulfur Group Donors