Fig. 3.

HexaBody-CD38 exerts FcγR-mediated effector functions. (a) ADCC was evaluated in calcein AM-labelled Daudi cells opsonized with indicated antibodies that were co-cultured for 4 h with human PBMC. Loss of Daudi cells relative to the ‘no antibody’ control was used as a measure for ADCC. Dose–response curves from one representative responding PBMC donor are shown (out of 10/22 responding PBMC donors), with error bars indicating variation of technical duplicates in the experiment. (b) ADCP was evaluated in calcein AM-labelled Daudi cells opsonized with indicated antibodies that were co-cultured for 24 h with CD11b⁺ human macrophages. The left panel shown the percentage loss of Daudi cells. The right panel shows the % macrophages with phagocytic activity. In each panel dose–response curves from one representative donor (n = 10) are shown. (c) Trogocytosis was evaluated in CTV- and PKH-26-labeled Wien-133 cells opsonized with indicated antibodies that were co-cultured with monocytes for 90 min. The left panel shows the % PKH-26⁺ monocytes as a measure for transfer of fluorescently labelled membrane. The right panel shows the percentage of CTV⁺ monocytes as a measure for transfer of fluorescently labelled cytosol. In each panel dose–response curves from one representative donor (n = 7) are shown. (d) Apoptosis was evaluated in Daudi cells that were incubated with 0.63 μg/mL antibody in the absence or presence of Fc fragment-specific goat anti-human IgG crosslinker. Cells were characterized as early (left panel) and late (right panel) apoptotic cells by flow cytometry. Results from 5 independent experiments are shown.