Immune Privilege Within: Regulatory T Cells Tip the Balance in Favor of Lymph Node Metastasis.

Kahn and colleagues reveal that lymph nodes (LN) provide an intrinsically immunosuppressive niche that prevents effector function of activated CD8+ T cells in LNs and allows immunogenic tumor cells to survive and drive cancer progression, independent of tumor-derived preconditioning. By locally suppressing IL2 availability, regulatory T cells in LNs impair CD8+ T-cell cytotoxicity-a mechanism with important implications for immune checkpoint therapy and LN-targeted immunomodulation. See related article by Kahn et al., p. 1949.