Effect of RTX on BCR activation in FL cell lines and normal B cells. RL (A,C) or DOHH2 (B) cells were incubated for 16 hours with 10 μg/mL of RTX or F(ab′)2 RTX, respectively, and then treated with anti-IgM or anti-IgG antibodies (10 μg/mL) during 5 minutes (A-B) or 2 hours (C). Nonstimulated and stimulated cells are represented by gray and black histograms, respectively. (D) RL or DOHH2 cells were treated with RTX or F(ab′)2 RTX, respectively (10 μg/mL, 16 hours). Untreated and treated cells with RTX are represented by gray and black histograms, respectively. (E) PBMCs isolated from healthy donors were incubated with F(ab′)2 RTX (10 μg/mL, 16 hours) and then treated with a mixture of anti-IgM/IgG antibody (10 μg/mL, 5 minutes). Nonstimulated and stimulated cells are represented by gray and black histograms, respectively. Syk phosphorylation on Y525 was measured by flow cytometry. Results are representative of at least 3 independent experiments.