Depletion of MZ B cells in mice with hemophilia A. Where indicated, mice with hemophilia A received MZ B-cell–depleting antibodies at days −4, −2, +10, and +20. Splenocytes from representative mice were then evaluated by flow cytometry to determine successful depletion. Representative flow plots of B220⁺CD21^hiCD23^lo/− cells following injection of saline, MZ B-cell–depleting antibody (MZ B cell depl), or isotype control antibody at days 0 (A), +10 (C), and +20 (E). Quantitative analysis of B220⁺CD21^hiCD23^lo/− cells (% MZ B cells) following administration of saline, MZ B-cell–depleting antibody (MZ B cell depl), or isotype control antibody at days 0 (B), +10 (D), and +20 (F). Error bars indicate standard deviation (SD). Horizontal lines represent mean of each group. *P < .03, **P < .003, ****P < .0001, 1-way ANOVA, post hoc Tukey test. SSC, side scatter.