Fig. 1.

Characterization of remaining B cells after repetitive anti-CD20 treatment. Mice were treated weekly with anti-CD20 (α-CD20) or isotype antibodies for three consecutive weeks. (A) Frequency of B cells in blood, spleen, inguinal lymph nodes, and bone marrow assessed by flow cytometry using antibodies against CD19 and B220 1 wk after the last injection. Shown is the mean percentage of B cells ± SEM, pregated on intact cells (n = 3 mice per group; *P < 0.05 and ***P < 0.001). (B) Expression of CD27 on B cells in blood, spleen, inguinal lymph nodes, and bone marrow determined by flow cytometry. Shown is the mean percentage of CD27⁺ cells ± SEM, pregated on CD19⁺ B220⁺ cells (n = 3 mice per group; ***P < 0.001). (C) Representative spleen sections stained for B220 by immunohistochemistry. (Scale bars: overview, 200 µm; inlay, 50 µm.)