(A) Apoptotic effect of anti-CD20 MoAbs on Ramos cells as shown by propidium iodide staining. 106 cells/mL were incubated with 10 μg/mL of the B1 or 1F5 anti-CD20 antibodies or with the control 64.1 anti-CD3 antibody for 24 hours in the presence or the absence of GAM cross-linker (50 μg/mL). Cell nuclei were stained with propidium iodide and analyzed by flow cytometry. Hypodiploid DNA peaks corresponding to apoptotic nuclei were quantified. Data are representative of five concordant experiments. (B) Kinetics of apoptosis induced by CD20 cross-linking. 106 cells/mL were incubated with or without 10 μg/mL anti-CD20 (B1) MoAb + 50 μg/mL GAM for 0 to 48 hours. Cell nuclei were stained with propidium iodide and analyzed by flow cytometry as described above. Anti-sIgM was used as a positive control. Data are representative of three similar experiments.
