FcγR-bearing macrophages mediate lymphoma depletion by CD20 mAb in vivo. (A-E) Mouse survival following BL3750 cell transfer on day 0 with CD20 or control mAb (250 μg/mouse) given intravenously on days 1, 7, 14, and 21 (downward ). (A) Mouse survival following transfer of 10⁴ BL3750 cells subcutaneously into FcRγ^−/− (n = 5/group), FcγRI^−/− (n = 4-5/group), FcγRIII^−/− (n = 5/group), or FcγRI/RIII^−/− (n = 7/group) recipient mice with CD20 (•) or control (○) mAb treatment. (B) Mouse survival following transfer of 10⁶ BL3750 cells subcutaneously into FcRγ^−/− (n = 5/group), FcγRI^−/− (n = 5/group), FcγRIII^−/− (n = 5/group), or FcγRI/RIII^−/− (n = 4-5/group) recipient mice with CD20 (•) or control (○) mAb treatment. (C) Mouse survival at day 60 following transfer of 10⁴ (left panel), 10⁵ (middle panel), or 10⁶ (right panel) BL3750 cells into wild-type, FcRγ^−/−, FcγRI^−/−, FcγRIII^−/−, or FcγRI/RIII^−/− recipient mice with CD20 (▬) or control (▭) mAb treatment (n = 4-7/group) as in panels A,B. Significant differences in mean survival of mice treated with CD20 or control mAbs as well as survival of CD20 mAb-treated mice are indicated (*P < .05; **P < .001). (D) Mouse survival following transfer of 10⁵ BL3750 cells intravenously into FcRγ^−/− mice with CD20 (•) or control (○) mAb treatment (n = 5/group). (E) Mouse survival following transfer of 10⁷ BL3750 cells into wild-type (—, n = 5/group) or FcγRIIB^−/− (, n = 5/group) mice with CD20 (•) or control (○) mAb treatment. (F) Mouse survival following transfer of 10⁵ BL3750 tumor cells subcutaneously on day 0 with CD20 (■ and •) or control (□ and ○) mAb (250 μg/mouse) given intraperitoneally on day 1 (downward ). Mice (n = 4-8/group) were given clodronate-encapsulated (■ and □) or PBS-encapsulated (• and ○) liposomes intravenously on days − 1, 2, 5, and 9 (downward ).