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Figure 2. Tumor-derived exosomes (TEXs) carry and deliver both immunosuppressive and immunostimulatory signals to immune cells in the lung tumor microenvironment. (A) Immune suppression. TEXs contribute to establish an immunosuppressive TME by inducing apoptosis and inhibiting the activity of effector T cells, skewing M2 polarization of macrophages, expanding myeloid-derived suppressor cells (MDSCs), suppressing DCs differentiation, and impairing the function of NK cells. (B) Immune stimulation. TEXs can also stimulate immune cells to support antitumor activities, including enhancing the activity of macrophages and NK cells, suppressing M2 macrophage polarization, and increase T cells activity directly or indirectly.