Table 2. . Suppressive effects of tumor-derived exosomes on functions of immune cells in the tumor microenvironment.

Direct TEX–immune cell interactions	Ref.
Apoptosis of activated antitumor effector T cells	[26,40]
Interference with normal differentiation	[41,42,44]
Inhibition of immune cell activation, proliferation and/or cytotoxicity	[14,26,46]
Polarization of the cytokine/chemokine profile to the tumor-promoting, proinflammatory profile	[23,29,38,41]
Regulation of immune cell migration to the tumor	[27,43,45,27]
Indirect interactions
Promotion of CD4+CD25+FOXP3+ Treg proliferation	[31,47]
Enhancement of Treg suppressor functions via, e.g., increased adenosine production	[14,31,32]
Expansion of MDSC	[37]

MDSC: Myeloid-derived suppressor cell; TEX: Tumor-derived exosomes.