ARE-del>WT chimera mice exhibit early signs of BM failure with HSPC composition similar to that of ARE-del mice. BM phenotype of chimeric mice was evaluated 8 weeks after reconstitution. (A) The bar graph shows the total BM cell number from WT>WT and ARE-del>WT (n = 8). (B) T-cell population in BM of chimeric mice was analyzed by using 7-color flow cytometry analyses. T cells were gated on live NKp46^–CD11b^–B220^–Gr1^–CD3⁺ populations. Bar graphs show both the total cell number of T cells and the percentage of live cells (n = 8). (C) The function of T cells in chimeric BM was determined by the intensity of cytokine responses against TCR agonists (anti-CD3/anti-CD28 antibodies [Abs]). Cytokine levels in the medium were measured 6 hours after stimulation by using a cytometric bead array. The bar graphs displays the concentration of each cytokine measured (n = 8). (D) HSPC composition in the BM of chimeric mice was analyzed on lineage^– BM cells by using flow cytometry. The bar graph shows the total cell number of each cell type (n = 8). (E) Total BM cells from WT>WT and ARE-del>WT mice were stained with fluorochrome-conjugated antibodies for lineage differentiation analysis. Dots plots are representative of 1 set of 3 experiments. (F) BM cells from all 4 groups (WT/control, WT/neutralizing, knockout (KO)/control and KO/neutralizing) were analyzed for LSK and LK populations and (G) erythropoiesis. Density and dot plots are representatives of 1 set of 3 experiments. Results are expressed as mean ± SD. *P < .05; **P < .01; ****P < .0001