Confirmation of exosome and cellular expression of identified microRNAs by quantitative real-time PCR. (A) Exosomes were isolated from 1 mL frozen plasma samples from 69 CLL patients and 15 healthy donors. Isolated exosome microRNA was examined by quantitative real-time PCR to determine the expression of miR29a-c, miR-150, and miR-155. All these microRNAs were expressed at significantly higher levels in CLL patients compared with healthy donors (***P < .001 for all comparisons). The expression data shown here are in a scale of negative CT (cycles required to reach threshold of detection), where a higher number represents higher expression and vice versa. (B) microRNAs were also isolated from the corresponding CD19⁺ CLL or normal B cells and analyzed by quantitative real-time PCR. Cellular levels of miR-150 and miR-155 were significantly higher in tumor cells from CLL patients vs normal B cells from healthy donors (*P = .029 and ***P < .001, respectively). There were no significant differences in the expression of cellular miR-29a-c between CLL patients and healthy donors.