Fig. 2

Radiotherapy induces a local anti-tumour immune response (a). Radiotherapy delivered to multiple sites may augment systemic responses (b). RT-induced immunogenic cell death stimulates the release of DAMPs and type 1 IFNs, which enhance antigen uptake and presentation by DCs. DCs present tumour antigens to T cell receptors, priming naïve T-cells to an effector phenotype. These T-cells migrate into the local tumour to exert their cytotoxic effects, or re-enter the circulation and migrate to distal, non-irradiated tumour sites (Panel A). At distal tumour sites, DCs may also activate T-cells against novel tumour antigens. RT delivered to multiple sites may therefore increase the quantity and diversity of migrating T-cells, enhancing the potential for systemic immune responses at non-irradiated sites (b). DAMPs damage-associated molecular patterns, DC dendritic cell, IFN interferon, MHC I major histocompatibility complex class I, RT radiotherapy, TCR T-cell receptor