Enhanced cytotoxicity and decreased CD8 dependence of human cancer-specific cytotoxic T lymphocytes after vaccination with low peptide dose

Cancer Immunol Immunother. 2012 Jun;61(6):817-26. doi: 10.1007/s00262-011-1140-1. Epub 2011 Nov 12.

Abstract

In mice, vaccination with high peptide doses generates higher frequencies of specific CD8+ T cells, but with lower avidity compared to vaccination with lower peptide doses. To investigate the impact of peptide dose on CD8+ T cell responses in humans, melanoma patients were vaccinated with 0.1 or 0.5 mg Melan-A/MART-1 peptide, mixed with CpG 7909 and Incomplete Freund's adjuvant. Neither the kinetics nor the amplitude of the Melan-A-specific CD8+ T cell responses differed between the two vaccination groups. Also, CD8+ T cell differentiation and cytokine production ex vivo were similar in the two groups. Interestingly, after low peptide dose vaccination, Melan-A-specific CD8+ T cells showed enhanced degranulation upon peptide stimulation, as assessed by CD107a upregulation and perforin release ex vivo. In accordance, CD8+ T cell clones derived from low peptide dose-vaccinated patients showed significantly increased degranulation and stronger cytotoxicity. In parallel, Melan-A-specific CD8+ T cells and clones from low peptide dose-vaccinated patients expressed lower CD8 levels, despite similar or even stronger binding to tetramers. Furthermore, CD8+ T cell clones from low peptide dose-vaccinated patients bound CD8 binding-deficient tetramers more efficiently, suggesting that they may express higher affinity TCRs. We conclude that low peptide dose vaccination generated CD8+ T cell responses with stronger cytotoxicity and lower CD8 dependence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cancer Vaccines / administration & dosage
  • Cancer Vaccines / immunology*
  • Chemotherapy, Adjuvant
  • Cytokines / biosynthesis
  • Dose-Response Relationship, Drug
  • Female
  • HLA-A2 Antigen / immunology
  • Humans
  • MART-1 Antigen / immunology*
  • Male
  • Melanoma / immunology*
  • Melanoma / pathology
  • Melanoma / therapy*
  • Neoplasm Staging
  • Oligodeoxyribonucleotides / administration & dosage
  • Oligodeoxyribonucleotides / immunology
  • Peptides / administration & dosage
  • Peptides / immunology*
  • T-Lymphocytes, Cytotoxic / immunology*
  • Vaccination*

Substances

  • Cancer Vaccines
  • Cytokines
  • HLA-A*02:01 antigen
  • HLA-A2 Antigen
  • MART-1 Antigen
  • Oligodeoxyribonucleotides
  • Peptides
  • ProMune