PD-1 blockade restores helper activity of tumor-infiltrating, exhausted PD-1hiCD39+ CD4 T cells

JCI Insight. 2021 Jan 25;6(2):e142513. doi: 10.1172/jci.insight.142513.


Tumor antigen-specific CD4 T cells accumulate at tumor sites, evoking their involvement in antitumor effector functions in situ. Contrary to CD8 cytotoxic T lymphocyte exhaustion, that of CD4 T cells remains poorly appreciated. Here, using phenotypic, transcriptomic, and functional approaches, we characterized CD4 T cell exhaustion in patients with head and neck, cervical, and ovarian cancer. We identified a CD4 tumor-infiltrating lymphocyte (TIL) population, defined by high PD-1 and CD39 expression, which contained high proportions of cytokine-producing cells, although the quantity of cytokines produced by these cells was low, evoking an exhausted state. Terminal exhaustion of CD4 TILs was instated regardless of TIM-3 expression, suggesting divergence with CD8 T cell exhaustion. scRNA-Seq and further phenotypic analyses uncovered similarities with the CD8 T cell exhaustion program. In particular, PD-1hiCD39+ CD4 TILs expressed the exhaustion transcription factor TOX and the chemokine CXCL13 and were tumor antigen specific. In vitro, PD-1 blockade enhanced CD4 TIL activation, as evidenced by increased CD154 expression and cytokine secretion, leading to improved dendritic cell maturation and consequently higher tumor-specific CD8 T cell proliferation. Our data identify exhausted CD4 TILs as players in responsiveness to immune checkpoint blockade.

Keywords: Cancer immunotherapy; Immunology; T cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Neoplasm / immunology
  • Apyrase / immunology
  • CD8-Positive T-Lymphocytes / immunology
  • Female
  • Gene Expression
  • Head and Neck Neoplasms / genetics
  • Head and Neck Neoplasms / immunology
  • Humans
  • Immune Tolerance / genetics
  • Immunity, Cellular / genetics
  • In Vitro Techniques
  • Lymphocyte Activation / genetics
  • Lymphocyte Cooperation / genetics
  • Lymphocytes, Tumor-Infiltrating / immunology*
  • Male
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / immunology
  • Programmed Cell Death 1 Receptor / antagonists & inhibitors*
  • Programmed Cell Death 1 Receptor / immunology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • T-Lymphocytes, Helper-Inducer / immunology*
  • Tumor Escape / genetics
  • Uterine Cervical Neoplasms / genetics
  • Uterine Cervical Neoplasms / immunology


  • Antigens, Neoplasm
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • RNA, Messenger
  • Apyrase
  • ENTPD1 protein, human