TLR-9 signaling and TCR stimulation co-regulate CD8(+) T cell-associated PD-1 expression

Immunol Lett. 2009 Dec 2;127(1):60-7. doi: 10.1016/j.imlet.2009.09.002. Epub 2009 Sep 12.

Abstract

Elevated Programmed Death-1 (PD-1) expression can inhibit T cell activity and is a potential barrier to achieving persisting and optimal immunity via therapeutic vaccination. Using a direct lymph node-targeted vaccination procedure that enabled uncoupling of synthetic peptide (signal 1, TCR-mediated) and adjuvant (signal 2, non-TCR-mediated), we evaluated the impact of varied doses of Toll-like receptor (TLR)-9 ligand CpG oligodeoxynucleotide (ODN) adjuvant on epitope-specific CD8(+) T cell-associated PD-1 expression. Peptide vaccination without adjuvant yielded CD8(+) T cells with significantly elevated PD-1 expression. This conferred impaired function ex vivo, but was reversible by antibody-mediated PD-1 blockade. By comparison, peptide vaccination with escalating doses of CpG ODN adjuvant yielded higher magnitudes of CD8(+) T cells with progressively lower PD-1 expression and greater ex vivo function. CpG ODN adjuvant in context of titrated peptide doses for vaccination yielded the lowest overall PD-1 expression levels, demonstrating that fine-tuning both TCR-independent (adjuvant dose) and -dependent (antigen dose) stimuli can synergize to co-regulate PD-1 expression on epitope-specific CD8(+) T cells. These data hint at strategies to elicit PD-1(low) CD8(+) T cells using TLR-9 ligand adjuvants, and also shed light on the PD-1-regulated homeostasis of CD8(+) T cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Neoplasm / immunology
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism*
  • DNA / administration & dosage
  • Female
  • Gene Expression Regulation* / drug effects
  • Gene Expression Regulation* / immunology
  • HLA-A Antigens / genetics
  • HLA-A2 Antigen
  • Immunization
  • Ligands
  • MART-1 Antigen
  • Mice
  • Mice, Transgenic
  • Neoplasm Proteins / immunology
  • Oligodeoxyribonucleotides
  • Peptide Fragments / immunology
  • Programmed Cell Death 1 Receptor
  • Receptors, Antigen, T-Cell / immunology
  • Receptors, Antigen, T-Cell / metabolism*
  • Receptors, Immunologic / biosynthesis*
  • Receptors, Immunologic / genetics
  • Receptors, Immunologic / immunology
  • Signal Transduction / drug effects
  • Signal Transduction / immunology
  • Toll-Like Receptor 9 / immunology
  • Toll-Like Receptor 9 / metabolism*

Substances

  • Antigens, Neoplasm
  • CpG ODN 1826
  • HLA-A Antigens
  • HLA-A*02:01 antigen
  • HLA-A2 Antigen
  • Ligands
  • MART-1 Antigen
  • Mlana protein, mouse
  • Neoplasm Proteins
  • Oligodeoxyribonucleotides
  • Pdcd1 protein, mouse
  • Peptide Fragments
  • Programmed Cell Death 1 Receptor
  • Receptors, Antigen, T-Cell
  • Receptors, Immunologic
  • Toll-Like Receptor 9
  • DNA