CD20 mAb treatment eliminates BL3750 tumors in vivo. (A-E) Mice were given 10⁵ BL3750 cells subcutaneously on day 0 with CD20 (•, n = 6) or control (○, n = 8) mAb (250 μg/mouse) given intravenously on days 1, 7, 14, and 21 (downward ). (A) Tumor volumes (± SEM) for CD20 or control mAb-treated mice. (B) Representative control mAb-treated mice exhibited tumors on their backs 5 weeks after BL3750 cell transfer, whereas tumors were not detectable in CD20 mAb-treated mice. (C) Circulating white blood cell numbers (± SEM) for CD20 or control mAb-treated mice. (A,C) Significant differences between sample means are indicated (*P < .05; **P < .001). (D) Circulating CD19⁺B220⁺ cells in representative mice 5 weeks after transfer of BL3750 tumor cells and CD20 or control mAb treatment. The percentages indicate relative frequencies of cells within the indicated gates. (E) Mouse tumor-free and overall survival rates following BL3750 cell transfers. (F) Mice were given 10⁵ BL3750 cells intravenously on day 0 with CD20 (•, n = 5) or control (○, n = 5) mAb (250 μg/mouse) given intravenously on days 1, 7, 14, and 21 (downward ). (G-J) Mouse survival following transfer of BL3750 cells subcutaneously on day 0 with CD20 (•) or control (○) mAb treatments as indicated (downward ). (G) Mouse survival following transfer of 10⁴ (n = 10 mice/group), 10⁶ (n = 4/group), or 10⁷ (n = 5/group) BL3750 cells on day 0, with CD20 or control mAb (250 μg/mouse) given at days 1, 7, 14, and 21. (H) Mouse survival following transfer of 10⁵ BL3750 cells with CD20 (2.5 μg/mouse, ♦; 10 μg, ▴; 25 μg, ■; or 100 μg, •) or control mAb (250 μg, ○) given on days 1, 7, 14, and 21 (n = 4-5/group). (I) Mouse survival (n = 6-8/group) following transfer of 10⁵ BL3750 cells with CD20 or control mAb (250 μg/mouse) given on day 1 (1×, ▴), on days 1 and 7 (2×, ■), or on days 1, 7, 14, and 21 (4×, •). (J) Mouse survival (n = 5-8/group) following transfer of 10⁵ BL3750 cells with CD20 or control mAb (250 μg/mouse) given on days 1 (+1, •), 3 (+3, ■), or 7 (+7, ▴).