Complement-mediated R-CDC is not mediated by caspase activation.

Cells of a representative CD20⁺⁺ patient with B-CLL were incubated in medium alone (C), or with 50 μg/mL rituximab in the absence (R) or presence (R+AB) of 10% AB serum. (A) Analysis by flow cytometry of the active form of caspase-3 after 24 hours of incubation. (B) Analysis of PARP cleavage by Western blot after 48 hours of incubation. (C) Analysis of DNA content by staining with propidium iodide after 48 hours of incubation. (D) Effect of 200 μM Z-VAD.fmk on cell viability after 24 hours of incubation. Z-VAD.fmk was preincubated for 1 hour prior to the addition of the indicated factors. Cell viability was quantified by exposure of phosphatidylserine residues.