The Role of Treg Cells in the Cancer Immunological Response

Problem statement: T cell-mediated immunosuppression has been observed for decades without clarification as to which factor was responsible for this observation. The identification of CD4+CD25+ regulatory T (Treg) cells represents a milestone in the filed of immunology and provides an explanation for T-cell-mediated immunosuppression. Although Treg cells were originally identified for their ability to prevent organ-specific autoimmune disease in mice, emerging evidence suggests that Treg cells play a pivotal role in tumor immunity and contribute to tumor growth and progression, thereby having an important impact on the outcome of cancer patients. Approach: This article reviewed the medical literature to describe how Treg cells affect anti-tumor immunity. Results: Treg cells suppressed anti-tumor immunity by inhibiting the effector functions of tumor-specific T cells and NK cells. Importantly, tumor cells played an active role in recruiting and generating Treg cells and creating a suppressive tumor microenvironment. Strategies to deplete Treg cells or inhibit their function had yielded promising results by enhancing anti-tumor immunity in experimental studies as well as clinical practice. Conclusion: A better understanding of the pathophysiology of Treg cells not only increased our knowledge in a variety of aspects of immunology but also potentially benefited cancer patients.