GMP are quantitatively and qualitatively normal in CMML. (A) Proportion of GMP (CD34⁺/CD38⁺/CD45RA⁺/CD123⁺) by flow cytometry among total BM CD34⁺ cells from CMML or aged-matched healthy control participants. Bar: median. (B) Total number of colonies (all granulomonocytic) per 1000 GMP grown in triplicate in methylcellulose for 14 days with 30% FBS and cytokines (SCF, IL-3, G-CSF, and EPO) from 5 control participants and 16 patients with CMML. (C) Fractions of GMP cells from fresh BM samples in G0/G1 (white), S (gray), and G2/M (black) phase after 1-hour incubation in Hoescht 33342 in the presence of 10% FBS and cytokines; mean and SD from independent samples. (D) Serial replating in methylcellulose of individual clones from sorted GMP of patients with CMML (solid) or control participants (dashed). Results: percentage of colonies relative to the initial number of clones seeded. Mean and SD from 3 independent samples for each group (*P < .05, Mann-Whitney U test); ns, nonsignificant.