Effects of antibodies targeting CD19, CD20, or CD22. Fresh PBMCs isolated from healthy donors were treated overnight with mAbs at the indicated concentrations. (A) Histograms showing cell count vs fluorescence intensity of CD22 (left) and CD21 (right) on B cells following treatment with 10 µg/mL of epratuzumab (red), hA19 (blue), or labetuzumab (black). Representative results from 3 independent experiments, which gave similar results. (B) Relative B-cell count (B cells) and levels of CD19, CD22, CD21, and CD79b following treatment with rituximab (10 µg/mL) or epratuzumab (10 µg/mL and 1 mg/mL). A representative graph of 3 independent experiments is shown. (C) PBMCs were treated in triplicate with epratuzumab or labetuzumab at varied concentrations (1 ng/mL to 10 mg/mL). The results are shown for 2 independent experiments using 2 different normal donors (N13 and N14). (D) Cells were treated with whole IgG or a F(ab′)2 fragment of epratuzumab at 10 µg/mL. A representative graph of 3 independent experiments is shown. Each plot is shown as the % MFI of the isotype control (labetuzumab) treatment at the same protein concentration. Each sample was evaluated in triplicate. Error bars represent SD.
