Fig. 1

Impact of leukemic EXOs on CD3 + T-cell viability: (A), a representative electron microscopic image of EXOs isolated by ultracentrifugation from AML blast 5-day culture supernatant and characterized by nanoparticle tracking analysis (NTA). The EXOs ranged in size from 50 to 150 nm, with a mean value of 100 nm. The concentration of EXOs reached 10 µg/ml. B Representative FACS histogram plots of an EXO sample stained with anti-CD63 and anti-CD81, which are typical markers of EXOs, confirming that the isolated vesicles are EXOs, and with anti-CD33, a myeloid blast marker, confirming that the EXOs are derived from leukemic blasts. C, D, and E Purified CD3, CD4 and CD8 T cells from HDs were cultured with 8 R-EXO samples isolated from AML blast patients or EXOs from HD PBMCs in the presence of IL-2 for 5 days. The purity of the isolated T cells was above 98%, as assessed by flow cytometry. Apoptosis was measured by FACS (cells were labeled with annexin-V-FITC and PI). Apoptosis was increased after coincubation of the cells with R-EXOs from AML blast patients compared to EXOs from HDs (C) p < 0.003, (D) p < 0.001, and (E) p < 0.03. F Representative FACS histogram of the percentage of GFP transferred from R-EXOs to T cells. The data are the mean ± SEM from experiments with eight AML samples. Representative data from five independent experiments are shown. All values are shown as the mean ± SEM. *p < 0.05; **p < 0.01 and *** p < 0.001