IL-1RA enhances elimination of CML stem cells in combination with NIL. BM cells from CML mice (CD45.1) treated with IL-1RA alone, NIL alone, or IL-1RA in combination with NIL were transplanted into irradiated secondary recipient mice (CD45.2) (n = 8 each). WBC counts (A), percent CD45.1 engraftment in PB (B), frequency of the mice developing leukemia (C), and survival (D) of the secondary recipient mice are shown. Another cohort of mice (n = 7 each) was treated with NIL alone or combination of NIL and IL-1RA for 4 weeks following which treatment was stopped, and the survival of these mice are shown (D). Results represent mean ± SEM. Significance values: *P < .05; **P < .01, ***P < .001, 2-way ANOVA and log-rank test.