Regulatory T cells express Tumor Necrosis Factor Receptor 2 with the highest intensity among CD4+ T cells in the draining lymph nodes of breast cancer.

Tumor Necrosis Factor Receptor 2 (TNFR2) is one of the receptors of TNF-α, which is expressed on various cell types. TNFR2 signaling has a balancing role between regulatory and effector functions of T cells. Herein, we investigated the expression of TNFR2 on regulatory T cells (Tregs) and non-Tregs in breast tumor-draining lymph nodes. Mononuclear cells were isolated from 16 axillary lymph nodes, and the expressions of TNFR2, Foxp3 and CD25 were assessed in CD4+ T cells by flow cytometry. Our results showed that the majority of TNFR2+CD4+ T cells were Foxp3-CD25-. However, the percentage of TNFR2+ cells was significantly higher in Foxp3+CD25+CD4+ Tregs compared to Foxp3-CD25-CD4+, Foxp3+CD25-CD4+, and Foxp3-CD25+CD4+ T cell subsets. Among these subsets, Foxp3+CD25+TNFR2+CD4+ T cells were found to have the highest intensity of TNFR2 expression. The intensity of Foxp3 expression in Foxp3+CD25+TNFR2+CD4+ Treg cells was significantly higher than in their TNFR2- counterpart. Collectively, we showed that most of TNFR2+CD4+ T lymphocytes were Foxp3-CD25-, while the majority of Foxp3+CD25+CD4+ Tregs were TNFR2+, and they expressed TNFR2 with the highest intensity. This report highlights the importance of TNFR2 expression on Tregs and paves the way for further investigation of the effects of TNF-α on the suppressive activity of Tregs in the tumor microenvironment.