Fig. 2: IL-6 does not promote intrinsic B-ALL chemoresistance.

a A flow cytometry plot showing IL-6R expression on the surface of leukemic cells in vitro. Histograms for IL-6R and isotype control-stained cells are overlaid. b A graph showing IL-6R expression in the bone marrow of leukemia-bearing mice pre- and post-doxorubicin (DOX) treatment. Data were quantified by flow cytometry. mCherry⁺ leukemia cells were used to distinguish stromal and leukemia cells. Median APC intensity from IL-6R stained cells minus isotype control-stained cells was calculated. Data from 2 independent experiments are shown, and represented as mean ± SEM. n = 6 per cohort, except n = 7 for both IL-6 KO-D2 post-doxorubicin stroma and IL-6 KO-D2 post-doxorubicin leukemia samples. ****p < 0.0001 by Ordinary one-way ANOVA test. c A dose–response curve showing leukemic cell viability in response to doxorubicin treatment in the presence or absence of IL-6 and/or sIL-6R. Viable cells were counted by flow cytometry 48 h after the addition of doxorubicin. Data from 4 independent experiments are shown, and represented as mean ± SEM. d A dose–response curve showing leukemic cell viability in the presence or absence of cytokines previously observed to be regulated by IL-6. Cells were treated as in (c) with the indicated cytokines. e A dose–response curve showing leukemic cell viability of cells co-cultured with bone marrow stromal cells (BMSC) from WT or IL-6 KO mice in response to doxorubicin treatment as in (c). f A graph showing p-STAT3 levels in the bone marrow of leukemia-bearing WT and IL-6 KO mice. There were no significant statistical comparisons between corresponding WT and IL-6 KO samples. Data are shown as in (b), from 2 independent experiments, and represented as mean ± SEM. n = 7 per cohort, except n = 6 for both IL-6 KO-D2 post-doxorubicin stroma and IL-6 KO-D2 post-doxorubicin leukemia samples. *p = 0.011, ****p < 0.0001 by Ordinary one-way ANOVA test. D2 = Day 2. Source data are provided as a ‘Source data’ file.