PMNs mediate trogocytosis of CLL B cells opsonized with anti-CD20 antibodies. Purified PMNs were cocultured with PKH67-labeled CLL B cells at a 1:3 E:T ratio and 10 µg/mL of anti-CD20 antibodies RTX-WT, RTX-GE, OBZ-WT, OBZ-GE, or CET control antibody. At 3 (3H) or 20 hours (20H), partial transfer of fluorochrome (trogocytosis) from CLL B-cell membranes to PMNs was measured by flow cytometry, after gating PMNs according to side scatter (SSC). (A) Example of the gating approach showing CLL B cells and PMNs at time point 0 (0H) as well as in coculture experiments at various times in the presence of CET or RTX-WT. The gates show the percentages of PMNs engaged in trogocytosis. (B-C) Results of experiments performed with the indicated antibodies and in which either (B) percentage trogocytosis or (C) mean PKH67 fluorescence on gated PMNs were measured. Results are the means and standard deviations of 5 independent experiments. *P < .05; **P < .01.