Increased number of regulatory T cells (T-regs) in the peripheral blood of patients with Her-2/neu-positive early breast cancer

Although progress has been made in establishing prognostic factors in breast cancer, there remains an urgent need for better prognostic and predictive scores for patients with early breast cancer. The important role of the immune system in controlling cancer progression is widely accepted. Regulatory T cells (T-regs) constitute a specialized T cell subset, which play an essential role in sustaining self-tolerance by negatively regulating immune responses. Increased frequencies of T-regs have been reported in the micromilieu of a variety of malignancies including breast cancer. However, little is known about the role of T-regs in the peripheral blood of cancer patients. We analyzed T-reg numbers in the peripheral blood of 292 patients with newly diagnosed early breast cancer by flow cytometry (CD4(+)CD25(+)CD127(low) cells) prior to planned breast surgery. Absolute T-reg numbers/A mu l varied from 4 to 212/A mu l. No difference could be detected in T-reg numbers between nodal negative and nodal positive, well and poorly differentiated or small and locally advanced cancers. However, T-reg numbers of Her-2/neu-positive patients were higher than in samples from patients with hormone receptor positive, Her-2/neu-negative cancers. In contrast, numbers of T-regs were not increased in triple negative patients. In addition, T-reg numbers were higher in patients with invasive ductal carcinomas as compared to invasive lobular cancers. Increased numbers of circulating T-regs may contribute to the higher metastatic potential of Her-2/neu-positive cells. A potential role as a prognostic or predictive parameter is currently being analyzed in a larger cohort of patients with sufficient follow-up.