CD11b+Ly6C++Ly6G- cells show distinct function in mice with chronic inflammation or tumor burden

BMC Immunol. 2012 Dec 12;13:69. doi: 10.1186/1471-2172-13-69.

Abstract

Background: S100A9 has been shown to be important for the function of so called Myeloid Derived Suppressor Cells (MDSC). Cells with a similar phenotype are also involved in pro-inflammatory processes, and we therefore wanted to investigate the gene expression and function of these cells in animals that were either subjected to chronic inflammation, or inoculated with tumors.

Methods: CD11b(+)Ly6C(++) and Ly6G(+) cells were isolated from spleen, tumor tissue or inflammatory granulomas. S100A9, Arginase 1 and iNOS gene expression in the various CD11b(+) cell populations was analyzed using Q-PCR. The suppressive activity of the CD11b(+) cell populations from different donors was studied in co-culture experiments.

Results: S100A9 was shown to be expressed mainly in splenic CD11b(+)Ly6C(+)G(+) cells both at the RNA and protein level. Arginase I and iNOS expression could be detected in both CD11b(+)Ly6C(+)Ly6G(+) and CD11b(+)Ly6C(+)G(-)/C(++)G(-) derived from tumors or a site of chronic inflammation, but was very low in the same cell populations isolated from the spleen. CD11b(+) cells isolated from mice with peritoneal chronic inflammation were able to stimulate T lymphocytes, while CD11b+ cells from mice with peritoneal tumors suppressed T cell growth.

Conclusion: An identical CD11b(+)Ly6C(++)G(-) cell population appears to have the ability to adopt immune stimulatory or immune suppressive functions dependent on the presence of a local inflammatory or tumor microenvironment. Thus, there is a functional plasticity in the CD11b(+)Ly6C(++)G(-) cell population that cannot be distinguished with the current molecular markers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Ly / metabolism*
  • Arginase / metabolism
  • CD11b Antigen / metabolism*
  • Calgranulin B / metabolism
  • Cell Proliferation
  • Chronic Disease
  • Female
  • Inflammation / enzymology
  • Inflammation / immunology*
  • Inflammation / pathology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Neoplasms / enzymology
  • Neoplasms / immunology*
  • Neoplasms / pathology
  • Nitric Oxide Synthase Type II / metabolism
  • Spleen / metabolism
  • Spleen / pathology
  • T-Lymphocytes / cytology
  • T-Lymphocytes / immunology
  • Terpenes
  • Tumor Burden / immunology*
  • Tumor Microenvironment / immunology

Substances

  • Antigens, Ly
  • CD11b Antigen
  • Calgranulin B
  • Ly-6C antigen, mouse
  • Ly6G antigen, mouse
  • Terpenes
  • pristane
  • Nitric Oxide Synthase Type II
  • Arginase