Fig. 2

The role of exosomes in tumour immunity after IR. IR directly damages irradiated cells and alters their components. In response to IR, irradiated cells suffering immunogenic death (ICD) produce and release a set of cytokines and chemokines. IR-induced molecules can be sorted into exosomes directly or stochastically during exosome formation. After secretion into the tumour microenvironment (TME), exosomes can be taken up by unirradiated bystander cells. The uptake of exosomal contents, such as DNA, microRNA, and proteins, results in altering cell signalling pathways, including metastasis, proliferation, and radioresistance, and induces genetic damage in recipient cells. For example, after IR, exosomes transfer increased numbers of TAAs with increased diversity to DCs stimulating a robust tumour-specific immune response in which specific CD8+ T cells travel to recognize and attack both primary and distant metastatic tumours. This finding may explain the abscopal effect to some extent