Tumor-infiltrating T lymphocytes: Friends or foes?

Ping Yu, Yang Xin Fu

Research output: Contribution to journalReview articlepeer-review

235 Scopus citations


The prognostic significance of tumor-infiltrating lymphocytes (TILs) has been a longstanding topic of debate. In cases where TILs have improved patient outcome, T lymphocytes are recognized as the main effectors of antitumor immune responses. However, recent studies have revealed that a subset of CD4 + T cells, referred to as CD4+CD25+ regulatory T cells (Treg), may accumulate in the tumor environment and suppress tumor-specific T-cell responses, thereby hindering tumor rejection. Hence, predicting tumor behavior on the basis of an indiscriminate evaluation of tumor-infiltrating T cells may result in inconsistent prognostic accuracy. The presence of infiltrating CD4+CD25+ Treg may be detrimental to the host defense against the tumor, while the presence of effector T lymphocytes, including CD8+ T cells and nonregulatory CD4+ helper T cells may be beneficial. Enhanced recruitment of antitumor effector T lymphocytes to tumor tissue in addition to inhibition of local Treg, may therefore be an ideal target for improving cancer immunotherapy. This article reviews the antitumor functions of T-lymphocytes, with special attention given to CD4+ regulatory T-cells within the tumor environment.

Original languageEnglish (US)
Pages (from-to)231-245
Number of pages15
JournalLaboratory Investigation
Issue number3
StatePublished - Mar 2006


  • CD4 T cells
  • CD4CD25 regulatory T cells
  • CD8 T cells
  • Immunotherapy
  • Tumor immunology
  • Tumor-infiltrating lymphocytes

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Molecular Biology
  • Cell Biology


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