Figure 1.

Anti-leukemic activity of a fixed saturating dose of anti-CD20 antibodies. (a–c) B-cell depletion was assessed using flow cytometry among PBMC from CLL patients, after 7 days (7d) of incubation with either rituximab (□) or GA101 (obinutuzumab) (▪). A saturating dose of 10 μg/ml was used in a complement-free medium, so results observed are due to both direct cell-death induction and antibody-dependent cell cytotoxicity. Boxes indicate means and whiskers confidence intervals. Comparisons were made using paired Student's t-test, all with P<0.05. (d) Depletion of leukemic cells according to CD20 surface antigen quantitative assessment. Cutoff value used (high vs low) was the median CD20 expression in a cohort of 21 patients (8100 antibodies bound per cell, using Quantibrite kits), and B-cell depletion was measured flow cytometrically after 7d in culture with 10 μg/ml of the indicated antibodies (rituximab, □ or GA101, ▪). Comparisons were made using paired Student's t-test, all with P<0.05.