De novo pre-BII-cell differentiation is impaired in GAL1^−/− mice. (A) BM B-cell differentiation from WT (n = 6) and GAL1-deficient mice (n = 4) was analyzed by FACS using antibodies specific for CD19, B220, IgM, CD23, CD25, and CD2. The gating strategy is shown in the figure and the B-cell subsets were defined as follows: pro-B/pre-BI, CD19⁺IgM⁻CD23⁻CD2⁻CD25⁻; pre-BII, CD19⁺IgM⁻CD23⁻CD2⁺CD25⁺; immature B, CD19⁺IgM⁺CD23⁻; recirculating B, CD19⁺IgM⁺CD23⁺. (B) Absolute cell numbers of the BM B-cell subsets. (C) BM B-cell differentiation from HU-treated WT and GAL1-deficient mice was analyzed 7 days after injection as described in panel A. (D) Absolute cell numbers of the BM B-cell subsets, 7 days after HU treatment. (E) Kinetics of recovery of the BM B-cell subsets at different time points following HU treatment (n = 4 for each condition). (F) Cell-cycle analysis was performed for HU-treated mice 7 days after injection, using TO-PRO-3. The DNA content of pre-BII cells and the percentage of cells in S/G₂/M are shown in the histograms. In the different panels, WT mice are shown in gray and GAL1^−/−, in black. Error bars represent SD. P values were determined using the Mann-Whitney unpaired test with a risk of 5% (*P = .022).