IL-1RA inhibits growth of murine CML stem cells and enhances elimination of CML stem cells in combination with NIL. CML (CD45.1) and normal (CD45.2) LTHSC were mixed with in a 1:1 ratio and cultured in murine CML BM CM with or without IL-1RA (2.5 µg/mL) for 7 days. The ratio of CD45.1⁺ to CD45.2⁺ cells is shown (A). BM cells from CML (CD45.1) and control (CD45.2) mice were mixed in a 1:1 ratio and transplanted into irradiated CML recipient mice (CD45.1.2). The recipient mice were treated with or without IL-1RA (150 mg/kg/d, subcutaneously) for 4 weeks. The ratio of CML to control cells is shown in (B). BM cells from BCR-ABL mice (CD45.1) were transplanted by tail vein injection (2 × 10⁶ cells/mouse) into recipient mice (CD45.2). Mice were treated with IL-1RA (150 mg/kg/d, subcutaneously), NIL (50 mg/kg/d, oral gavage), IL-1RA⁺NIL, or vehicle for 3 weeks (n = 10 each). PB WBC count (C); spleen weight (D); percentage CD45.1⁺ cells in PB (E), BM (F) and spleen (G); and number of LTHSC (H), MPP (I), CMP (J) and GMP (K) in the BM are shown. Results represent mean ± SEM. Significance values: *P < .05; **P < .01; ***P < .001, 2-way ANOVA. NS, not significant.