Tumor draining lymph nodes form the first line of defense against tumor dissemination. Lymphocyte subpopulations activated during anti-tumor response determine the outcome of host-tumor interaction. In the present study we explored the percentages of different subtypes of CD4+ lymphocytes, including regulatory cells (TFR, CD25-, and CD25+ Treg cells), helper subsets (Th1, Th2, Th17, and Tfh cells), and the expression level of their cognate cytokines (IFNγ, IL4, and IL17) in tumor draining lymph nodes of patients with breast cancer, and compared the results between node negative (LN-) and node positive (LN+) patients. Forty seven sentinel and non-sentinel auxiliary lymph nodes with or without tumor involvement were collected from untreated breast cancer patients undergoing surgical resection. Mononuclear cells obtained from fresh homogenized lymph nodes were subjected to surface and intracellular staining by flow cytometry. The results revealed the presence of a newly identified subtype of regulatory T cells, TFR, as well as CD25- Treg cells in TDLNs of the breast cancer patients. In addition, evaluation of different helper and regulatory subgroups of CD4+ T lymphocytes showed that upon metastasis of tumor cells to lymph nodes together with the progression of the disease stage, the immune responses changed from an inflammatory to an inhibitory state, as evidenced by a reduction in pro-inflammatory and anti-tumor cytokines, IL17 and IFNγ, as well as an increase in pro-tumorigenic phenotypes, Th2 and Treg cells. This situation may provide a favorable condition for tumor growth and spread.
Keywords: Breast cancer; CD25− Treg; T helper subsets; TFR.
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