CD39+ and Tim3+ T reg are potential effector cells in the peripheral blood and tumor microenvironment of head and neck squamous cell carcinoma patients

Introduction Regulatory T cells (T reg) constitute an immunosuppressive, tumor-promoting cell population in the head and neck tumor microenvironment. However, T reg are phenotypically and functionally heterogeneous and can be subdivided into naive (nT reg, CD45RA+FoxP3low), effector (eT reg, CD45RA−FoxP3high) and non-suppressive (nsT reg, CD45RA−FOXP3low) subpopulations. Here we investigate the role of eT reg in head and neck squamous cell carcinoma (HNSCC).