In vivo LXR agonist treatment limits BPDCN-induced cytopenia, spleen and bone marrow infiltration by BPDCN, and also improves overall mouse survival. NSG mice were sublethally irradiated (2 Gy), and then injected IV with 1 × 106 CAL-1 cells. After 7 days, mice were treated with 2 doses of the LXR agonist T0901317 (30 mg/kg or 60 mg/kg) or with vehicle control (PBS/DMSO 50%) every 2 days, until the end of the experiments (4 mice per group, 3 independent experiments). (A) Blood samples were collected every 4 days to assess RBC and Hb concentration. Cumulative data expressed as mean ± SEM are shown (*P < .05, **P < .01, Mann-Whitney). (B) At the end of the experiments (J20 ± 2), spleens were extracted and measured to evaluate BPDCN spleen involvement. (C) Spleens and bone marrow were collected in order to perform CAL-1 cell quantification. Cells were stained with the following antibodies: human CD45 (hCD45), murine CD45 (mCD45), CD123, and BDCA4 and analyzed by cytometry. Dot plots illustrate the gating strategy with identification of murine cells using mCD45 gating with irradiated mice used as control. Human CAL-1 cells were identified using hCD45, CD123, and BDCA4 staining. Cultured CAL-1 cells were used as control for this staining. Percentage of cell infiltration was calculated as follows: CAL-1 count/(hCD45 + mCD45 counts). Histograms represent cumulative data of 1 experiment of 3 expressed as mean ± SEM of CAL-1 cell infiltration percentage from 5 mice. (D) Overall survival of BPDCN-inoculated mice treated with LXR agonist T0901317 (30 mg/kg, pink triangles; 60 mg/kg, red triangles) or with vehicle (black squares). Irradiated mice (gray circles) were used as control. Statistical comparisons were performed between vehicle and treated groups using the Mantel-Cox test (*P < .05, **P < .001). (E) Mean overall survival of BPDCN-inoculated mice treated with LXR agonist or vehicle. Bars correspond to the mean of survival time (*P < .05, Mann-Whitney). Results from 1 additional experiment with 5 mice per group are shown.
