Table 2.

Immunosuppressive effects of exosomes secreted by nontumor cells.

Origin of Exosomes	Target Cells	Functional Molecules	Mechanisms	References
Cancer-associated fibroblasts	PD-L1	miR-92	Promote YAP1 nuclear translocation and increase PD-L1 transcription	[83]
Tregs	T cells and B cells	IL-35	Induce peripheral tolerance of T cells and B cells by transferring IL-35	[84,85]
	T cells and DCs	miRNAs	Inhibit proliferation and cytokine release of Th1 cells and DCs	[86,87]
MDSCs	MDSCs	S100A8 and S100A9	Mediate accumulation and immunosuppressive function of MDSCs	[88,89]
	MDSCs	miRNAs	Promote expansion, differentiation survival, and IL-10 production of MDSCs	[90,91,92,93]
	T cells	——	Induce apoptosis of T cells	[94,95]
	Macrophages	——	Induce decline of M1 macrophages and expansion of M2 macrophages	[96]
Tumor-associated macrophages	——	miR-155-5p	Impair stability of IL-6	[97]
	Ovarian cancer cells	miR-29a-3p	Increase expression of PD-L1	[98]
	T cells	——	Inhibit cell cytotoxicity of CD8 T cells	[99]