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-alpha, 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-alpha on the suppressive activity of Tregs in the tumor microenvironment.