Binding of radiolabeled CD20 mAb F(ab′)₂ and Fab′ fragments to Daudi and EHRB cells.¹²⁵I-labeled F(ab′) 2 (A-B) or Fab′ fragments (C-D) of CD20 mAbs were incubated with EHRB (A,C) or Daudi (B,D) cells for 2 hours at 37°C. The cell-bound and free ¹²⁵I-labeled mAbs were then separated by centrifugation through phthalate oils, and the cell pellets together with bound antibody were counted for radioactivity. Symbols: rituximab, ▪; 7D8, ▴; 2F2, ▾ ; 11B8, •; and B1, □. The results show 1 of at least 2 separate experiments with similar results.