Trogocytosis efficiency correlates with CD20 occupancy and expression levels. Purified PMNs were cocultured with PKH67-labeled CLL B cells at a 1:3 E:T ratio for 3 hours. (A) CLL B cells were opsonized with 0.008 to 4 µg/mL of RTX-GE or OBZ-GE, and trogocytosis was measured at 3 hours by flow cytometry. The PKH67 MFI on PMNs, as a percentage of the positive control with 4 µg/mL RTX-GE, is shown. Data are the means and standard deviations of 5 experiments with 5 different CLL B-cell targets. (B) The PKH67 MFI values obtained in 20 experiments performed with PMNs from 9 healthy donors and 7 different B-cell targets (from 7 patients with CLL), opsonized with 10 µg/mL of RTX-GE (left panel) or OBZ-GE (right panel), were plotted against the number of CD20 molecules per CLL B cells (log scale). Each CLL B-cell target is represented by a different symbol or color. (C) The efficiency of trogocytosis by PMNs from a single healthy donor of 10 different CLL B-cell targets, all opsonized with 10 µg/mL of RTX-GE or OBZ-GE, was measured. The MFI of PKH67 on PMNs was plotted against the number of CD20 molecules per CLL B cell.