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Fig. 1 | Journal of Hematology & Oncology

Fig. 1

From: Abscopal effect of radiotherapy combined with immune checkpoint inhibitors

Fig. 1

Mechanism of the abscopal effect. Radiotherapy (RT) can lead to immunogenic cell death and the release of tumor antigens by irradiated tumor cells. These neoantigens are taken up by antigen-presenting cells (APCs), such as dendritic cells (DCs) and phagocytic cells. The APCs interact with tumor antigens and then migrate to the lymph nodes where they present antigens to T cells, a process that is mediated by the MHC pathway and other co-stimulatory signals, such as CD80 and CD28. After activation by multiple signals, T cells, especially the CD8+ T cells, are activated and begin to propagate. As a result, activated effector T cells exit the lymph nodes and home to tumors, including primary tumors and non-irradiated tumor metastases, to exert their effect of killing tumor cells. However, cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) competitively combines with CD80/86 and inhibits the activation of T cells. Following T cell activation, programmed cell death 1 (PD-1) receptors that are expressed on the T cell surface bind primarily to programmed death-ligand 1 (PD-L1) and inhibit immune responses. The administration of immune checkpoint blockades of CTLA-1, PD-1, and PD-L1 can enhance the anti-tumor immunity of RT

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