GlcNAc exacerbates the severity of an advanced systemic mastocytosis (AdvSM) phenotype. (A) The proliferation of human MCs, ROSA^{KIT WT}, and ROSA^{KIT D816V} cells, was assessed after treatment with or without 20 mM GlcNAc, and the cells were counted using a Cellometer Auto T4 at days 0, 2, 4, and 8. (B) Schema of in vivo administration of 300 mg/kg GlcNAc to ROSA^D816-Gluc transplanted mice after irradiation with 1.5 Gy (n = 10, 5 per group). (C) Measure of GlcNAc activity (in relative luciferase units [RLU]) in PBS- or GlcNAc-treated mice from week 3 (W3) to week 7 (W7). (D) Number of Gluc⁺ cells circulating in the plasma of mice from W3 to W7, as measured by fluorescence-activated cell sorting (FACS). (E) Number of GFP⁺ and CFP⁺ cells in the bone marrow of PBS- or GlcNAc-treated mice, as measured by FACS. (F) Number of GFP⁺ and CFP⁺ cells in the spleens of PBS- or GlcNAc-treated mice, as measured by FACS. (G) Weights of spleens at W7 in PBS or GlcNAc-treated mice. (H) Plasmatic concentration of GlcNAc measured by LC-MS/MS in nontransplanted mice, transplanted mice, and GlcNAc-treated transplanted mice. Sampling was done after 7 weeks of treatment, 2 hours after the last injection of GlcNAc. The values in the graphs are presented as the means ± SD (nonsignificant, *P < .05, **P < .01, ***P < .001; 2-tailed, unpaired Student t test).