Accumulation of regulatory T cells in draining lymph nodes : a potential target for breast cancer immunotherapy?

In breast cancer, regional lymph nodes are often the first site of metastasis. From a clinical standpoint, the tumor invasion in draining lymph nodes is an important step in disease progression and a prognostic indicator of the risk of recurrence. 

In this article, Eliane Piaggio's team uses high-dimensional flow cytometry, functional assays, T-cell receptor (TCR) repertoire analysis, and RNA sequencing to characterize the immune phenotype, the function and the dynamic of regulatory T cells (Tregs). The study compares the cells present in paired non-invaded and invaded tumor draining lymph nodes as well as in the tumor. 

Finally, the team describes a transcriptomic signature shared between the tumor Tregs and the lymph node Tregs. This is associated with a poor prognosis. The analyses also show a circulation of  Tregs between the lymph nodes and the tumor and a Tconv/Treg conversion. In conclusion, these results show that lymph node Tregs are functional and express a pattern of co-receptors which could be a new therapeutic target.