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Fig. 1 | Biomarker Research

Fig. 1

From: The role of exosomes in tumour immunity under radiotherapy: eliciting abscopal effects?

Fig. 1

Exosomal PD-L1 contributes to resistance to ICI therapy. a. Tumour cells express surface PD-L1, which directly binds to PD-1 on T cells, eliciting an immune checkpoint response. After the immune checkpoint response, T cell activation is suppressed and leads dysfunction or apoptosis, which directly inhibits antitumour immunity. b. Immune checkpoint inhibitors (ICIs) can bind to immune checkpoints, such as PD-1/L1 and CTLA-4, and free exhausted T cells to rejuvenate antitumour immunity. c. Tumours upregulate the expression of PD-L1 to avoid activated T cell attack. Moreover, tumour cells release exosomal PD-L1, which has similar effects as tumour-derived PD-L1. Exosomal PD-L1 can bind to PD-1 on T cells and ICIs, thereby inhibiting T cell activation and proliferation and inducing T cell apoptosis and resistance to ICI therapy

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