CD80 and chronic myelogenous leukemia, BCR-ABL1 positive: Purified exosomes isolated from serum of patients with CML satisfied three major criteria as exosomes: they had a size of 50–100 nm in diameter (Fig. 4a1–2) and a density of 1.13–1.21 g/dl in a sucrose gradient; were enriched with CD80 (Fig. 4a3) and expressed Tsg101 and CD63 proteins (Fig. 4B).