High levels of exosomes are detected in CLL plasma and their concentrations are not correlated with absolute lymphocyte counts. (A) Exosomes were isolated from 40 CLL patients’ plasma and 8 healthy donors’ plasma, and the exosome concentrations were determined by NTA. Plasma from CLL patients showed higher concentrations of exosomes compared with plasma from healthy donors (*P = .026). (B) No significant correlation between plasma exosome concentrations and absolute lymphocyte counts was determined, as calculated by Spearman’s correlation coefficient (n = 39, ρ = 0.04). (C) Plasma exosome concentrations in IGHV-unmutated CLL was not significantly higher than in IGHV-mutated CLL; however, there is a trend in which more unmutated CLL patients exhibit elevated exosome concentrations vs IGHV-mutated CLL patients.