Fig. 1

Exosomes from tumor or immune cells stimulate or suppress anti-cancer immunity. a Tumor-derived exosomes bearing antigens stimulate CD8⁺ T cells via dendritic cells (DCs). HSPs-containing exosomes promote the activation and enhance the cytotoxicity of NK cells. b RNA-containing exosomes activate regulatory T cells. Tumor-derived exosomes can stimulate tumor-associated macrophages to adopt a tumor-promoting M2-like phenotype. Similarly, tumor-derived exosomes promote N2-like polarization in tumor-associated neutrophils. PD-L1-bearing exosomes inhibit the cytotoxicity of CD8⁺ T cells. c B cell-derived exosomes carrying MHC II stimulate CD4⁺ T cells by specifically targeting receptors on CD4⁺ T cells. DCs present antigens and MHC I to CD8⁺ T cells, resulting in their activation. Macrophages present antigens to CD4⁺ T cells via DCs, ultimately triggering CD4⁺ T cells activation. d Antigen-bearing exosomes suppress the function of CD8⁺ T cells and CD4⁺ T cells in bone marrow-derived cells, tumor-associated macrophages, and regulatory T cells