Neuropilin-1 is required for T_reg stability

The development of an anticancer immune response is often precluded by an immunosuppressive microenvironment, which can be created by the presence of large numbers of regulatory T cells (T_reg). The findings of research using a mouse model of melanoma demonstrate the importance of neuropilin-1 (Nrp1) to T_reg-mediated immunosuppression: Nrp1^−/− T_reg were found to enhance antitumour immunity, often resulting in tumour clearance. However, only a proportion of Nrp1^−/− T_reg were required for this effect. These enhanced antitumour effects were found to be mediated by IFNγ release from Nrp1^−/− T_reg. Further investigations revealed that IFNγ-induced T_reg fragility is required for a response to anti-programmed cell death protein 1 antibodies in mice, thus highlighting the central role of T_reg in the generation and maintenance of an immunosuppressed tumour microenvironment.