Skewing the Balance of Regulatory T-Cells and T-Helper 17 Cells in Breast Cancer Patients

This study investigated the distribution of interleukin (IL)-17-producing CD4(+) T-cells (T-helper [Th17] cells) in relation to CD4(+)CD25(+)CD127(-) cells (regulatory T-cells [T(reg)]) in tumour-infiltrating lymphocytes (TILs) and peripheral blood mononuclear cells (PBMCs) from breast cancer patients. The Th17 and T(reg) cells were evaluated by flow cytometry and reported as a percentage of total CD4(+) cells. In TILs from early breast cancer patients (n = 12), the frequency of Th17 cells was significantly higher than in PBMCs (14.5 ± 7.2% versus 6.9 ± 2.1%). In TILs from patients with advanced breast cancer (n = 15), the frequency of Th17 cells was also significantly higher than that in PBMCs (9.1 ± 5.7% versus 3.2 ± 2.3%) but lower compared with early disease. The Th17/T(reg) ratio in TILs was markedly increased in early versus advanced disease. In conclusion, Th17 and T(reg) cell accumulation in the tumour microenvironment of breast cancer occurred in early disease; Th17 cell infiltration gradually decreased and T(reg) cells accumulated with disease progression.