GAL1- and IL-7–expressing stromal cells are distinct populations. (A) BM stromal cells from C57Bl/6 mice (n = 5) were analyzed by flow cytometry as described in Figure 1H and were further characterized using antibodies specific for CD54, CD31, PDGFRa, CD106, and BP1. The analysis of the stromal cells was performed on the GAL1⁺ and GAL1⁻ cell populations. The gating strategy is shown in the figure. (B) CD45⁻Lin⁻ stromal cells from IL-7-GFP reporter mice (n = 4) were analyzed by flow cytometry as described in panel A. The phenotypic analysis was performed on the GFP⁺ population. (C-D) BM stromal cells from C57Bl/6 mice were defined as shown in Figure 1H and were sorted by flow cytometry using, in addition, antibodies specific for CD54, CD31, CD106, and BP1. (C) mRNA was prepared from the CD54⁺CD31⁻ (population 1), CD54⁺CD31⁺ (population 2), and CD54⁻CD31⁻ (population 3) stromal cells (left panel). RT-PCR was performed using primers specific for GAL1, IL-7, and CXCL12 (right panel). (D) The CD54⁺CD31⁻ population was further refined by cell sorting using anti-BP1 and anti-CD106 antibodies in 2 subpopulations: CD106⁺BP1⁺ (population 4) and CD106⁻BP1⁻ (population 5). The RT-PCR was performed using primers specific for GAL1, IL-7, and CXCL12 (right panel). The results of RT-PCR are representative of 3 independent experiments.