Role of immature myeloid cells in mechanisms of immune evasion in cancer

Cancer Immunol Immunother. 2006 Mar;55(3):237-45. doi: 10.1007/s00262-005-0048-z. Epub 2005 Jul 27.

Abstract

Tumor affects myelopoiesis by inhibiting the process of differentiation/maturation of antigen-presenting cells from their myeloid precursors and by stimulating an accumulation of immature myeloid cells in cancer patients and tumor-bearing mice. These immature myeloid cells can contribute greatly to tumor progression and promote tumor evasion from immune attack: i) by inhibiting development of adaptive immune responses against tumor in lymphoid organs; ii) by migrating into tumor site and differentiating there into highly immune suppressive tumor-associated macrophages. Immature myeloid cells and tumor-associated macrophages utilize different JAK/STAT signaling pathways and different mechanisms to control T cell responses, which include increased production of TGF-beta, reactive oxygen species, peroxynitrites, as well as enhanced L-arginine metabolism. Understanding of precise mechanisms, which tumors use to affect differentiation of APC from myeloid cell precursors and inhibit T cell responses, could help to develop new approaches for cancer therapy and substantially improve efficiency of existing cancer vaccination strategies.

Publication types

  • Review

MeSH terms

  • Animals
  • Antigen-Presenting Cells / cytology
  • Antigen-Presenting Cells / immunology
  • Cell Differentiation
  • Humans
  • Immune Tolerance / immunology*
  • Myeloid Cells / cytology*
  • Myeloid Cells / immunology*
  • Neoplasms / immunology*
  • Tumor Escape / immunology*