Expression of TNFRs by B and T Lymphocytes in Tumor-Draining Lymph Nodes

The expression pattern of membranous TNF-α is distinct from its intracellular form in the breast cancer draining lymph nodes

Tumor necrosis factor-alpha (TNF-α) is mostly known as a soluble cytokine. However, this study focused on its membranous form whose significance is rarely investigated in antitumor immunity. Herein, we assessed the expression of both membranous and intracellular forms of TNF-α (m/icTNF-α) in the lymphocytes derived from breast cancer-draining lymph nodes. CD4⁺T cells were the main subset expressing mTNF-α with the highest intensity, whereas icTNF-α expression was most intense in CD8⁺T cells. An inverse correlation was seen between the frequency of mTNF-α and the expression intensity of this cytokine in B cells. In the clinical context, the higher intensity of mTNF-α expression in CD19⁺ cells correlated with poor prognosticators, while the frequency of mTNF-α⁺CD19⁺ cells showed a reverse correlation with the number of involved lymph nodes. The two forms of TNF-α did not show similar associations with cancer parameters, which highlights the complex role of this cytokine in breast cancer immunity.

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.