The role of CD200–CD200R in tumor immune evasion

• PDE model of tumor growth.
• Tumor associated macrophages.
• The transition from M1 to M2 macrophages under influence of the cancer.
• Role of CD200R in immunoediting.
• IL-10 downregulation in M2 and IL-12 upregulation in M1.

CD200 is a cell membrane protein that interacts with CD200 receptor (CD200R) of myeloid lineage cells. During tumor initiation and progression, CD200-positive tumor cells can interact with M1 and M2 macrophages through CD200–CD200R-compex, and downregulate IL-10 and IL-12 productions secreted primarily by M2 and M1 macrophages, respectively. In the tumor microenvironment, IL-10 inhibits the activation of cytotoxic T lymphocytes (CTL), while IL-12 enhances CTL activation. In this paper, we used a system approach to determine the combined effect of CD200–CD200R interaction on tumor proliferation by developing a mathematical model. We demonstrate that blocking CD200 on tumor cells may have opposite effects on tumor proliferation depending on the “affinity” of the macrophages to form the CD200–CD200R-complex with tumor cells. Our results help understanding the complexities of tumor microenvironment.