Biologically-active exosomes in plasma of AML patients inhibit innate immunity and promote leukemia progression

AML patients are reported to have impairments of immune cells which contribute to leukemia progression. Tumor-derived exosomes (TEX) have recently emerged as carriers of the molecular and genetic cargo with potent immunosuppressive properties. We showed that plasma of newly-diagnosed AML patients prior to any therapy contained high levels of exosomal proteins relative to those in plasma of normal donors (NC). AML exosomes were enriched in membrane-associated TGF-β1, MICA/MICB and markers of myeloid blasts. We hypothesize that these plasma-derived virus-size (30-100nm) membrane-bound vesicles operating in AML deliver suppressive signals to immune cells and thus may promote leukemia progression