Figure 4. Long-term anti-mCD20 treatment significantly reduces antibody-secreting cells.

24–28 week NZB/NZWF1 female mice with high titer anti-dsDNA antibodies were dosed weekly with anti-mCD20 antibody or control IgG (n=6, Ctrl). One group was treated 4 times weekly and sacrificed one week later after last treatment (n=5, 4 wks). One group was treated weekly×4 (n=4) and sacrificed 8 weeks later (4/8 wks). Another group was treated weekly×12 (n=4) and sacrificed 1 week after the last treatment (12 wks). Cells from spleen, bone marrow (BM) and kidney were collected and total IgG and dsDNA IgG ASCs were determined by ELISpot. Solid circle for control mice (treated for 12 wk with control IgG), solid diamond for 4 week treated mice; solid up-triangle for the mice 4/8 week mice; solid down-triangle for 12 week treated mice. Bars represent mean±SEM. p values were calculated by Mann-Whitney test. A. total IgG ASCs from spleen, BM and kidney. Significant reduction of total IgG ASCs is observed after 12 week B cell depletion with anti-mCD20 antibody compared with untreated control mice. B. anti-dsDNA IgG ASCs from spleen, BM and kidney. Significant reduction of anti-dsDNA IgG ASCs is observed after 12 week B cell depletion with anti-mCD20 antibody compared with untreated control mice. C. the percentage of anti-dsDNA IgG ASCs/total IgG ASCs in spleen (left scale), BM (left scale) and kidney (right scale), respectively. Significant reduction of dsDNA/IgG ratio is observed after anti-mCD20 antibody treatment. D. The antibody in plasma was measured before treatment (baseline) and at endpoint, and the change relative to baseline calculated. After 12 week B cell depletion, anti-dsDNA antibody level is significantly decreased (control vs. 12 wk p value=0.0095; control vs. 4/8 wk p value NS).