Figure 4.

Tumor-derived exosomes in the TME or in the plasma of cancer patients carry an excess of immunoinhibitory proteins and immune checkpoint inhibitors. In A, Western blots of exosomes isolated by size exclusion chromatography from plasma of a cancer patient. TSG101 is an endocytic marker confirming the exosome origin from the endocytic compartment of the parent tumor cell. In B, a scanning electron microscope image of exosomes isolated from plasma of a patient with ovarian carcinoma (courtesy of Dr. Marta Szajnik; reproduced under the terms of the Creative Commons Attribution License from ref. 143).