Immune cells within the tumor microenvironment: Biological functions and roles in cancer immunotherapy

Cancer Lett. 2020 Feb 1:470:126-133. doi: 10.1016/j.canlet.2019.11.009. Epub 2019 Nov 12.


The immune cells within the tumor microenvironment (TME) play important roles in tumorigenesis. It has been known that these tumor associated immune cells may possess tumor-antagonizing or tumor-promoting functions. Although the tumor-antagonizing immune cells within TME tend to target and kill the cancer cells in the early stage of tumorigenesis, the cancer cells seems to eventually escape from immune surveillance and even inhibit the cytotoxic function of tumor-antagonizing immune cells through a variety of mechanisms. The immune evasion capability, as a new hallmark of cancer, accidently provides opportunities for new strategies of cancer therapy, namely harnessing the immune cells to battle the cancer cells. Recently, the administrations of immune checkpoint modulators (represented by anti-CTLA4 and anti-PD antibodies) and adoptive immune cells (represented by CAR-T) have exhibited unexpected antitumor effect in multiple types of cancer, bringing a new era for cancer therapy. Here, we review the biological functions of immune cells within TME and their roles in cancer immunotherapy, and discuss the perspectives of the basic studies for improving the effectiveness of the clinical use.

Keywords: Cancer immunotherapy; Immune cells; Tumor microenvironment.

Publication types

  • Review

MeSH terms

  • Antineoplastic Agents, Immunological / pharmacology
  • Antineoplastic Agents, Immunological / therapeutic use*
  • CTLA-4 Antigen / antagonists & inhibitors
  • CTLA-4 Antigen / immunology
  • Cancer Vaccines / immunology
  • Cancer Vaccines / therapeutic use*
  • Clinical Trials as Topic
  • Humans
  • Immunity, Cellular
  • Immunotherapy, Adoptive / methods*
  • Immunotherapy, Adoptive / trends
  • Neoplasms / immunology
  • Neoplasms / therapy*
  • Programmed Cell Death 1 Receptor / antagonists & inhibitors
  • Programmed Cell Death 1 Receptor / immunology
  • Receptors, Chimeric Antigen / immunology
  • Treatment Outcome
  • Tumor Microenvironment / drug effects
  • Tumor Microenvironment / immunology*


  • Antineoplastic Agents, Immunological
  • CTLA-4 Antigen
  • CTLA4 protein, human
  • Cancer Vaccines
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • Receptors, Chimeric Antigen