Six month old NZB/NZWF1 mice (≥ 100 mg/dl proteinuria) were treated with anti-mCD20 (n=9), anti-mCD20 with BR3-Fc (n=4) or control antibody (IgG2a) (n=8) (300 μg) once per week for 4 weeks. B220+ B cells were enumerated 1 week after the final antibody injection in multiple tissues by flow cytometry. (A) Depletion of B cells (B220+) in spleen (SPLN), bone marrow (BM), peritoneum (PERIT), peripheral blood (PBL), and lymph node (LN), reported as the B220+ B cell % of the lymphocyte gate (mean +/− SE). (B) Depletion in B cell subsets in spleen, peritoneum and bone marrow. B cell subsets were defined as in the Methods.