Phagocytosis of apoptotic cells. (A) Immature or matured (with different TLR ligands) MDCs (green) and apoptotic HEK-293 cells (red) were labeled with membrane dyes and were cocultivated for 24 hours. In some experiments, 10⁶ zymosan particles or 10.0 μg/mL of the ECD of hDectin-1b was added to the cultures to inhibit hDectin-1–mediated recognition. Uptake of apoptotic HEK-293 cells by MDCs is represented as the double-positive cell fraction. Representative 2-color dot plots are shown. Percentage of double-positive cells is shown in the upper right quadrant. (B) The diagram represents mean (± SD) of 3 independent experiments using different donors. *P < .05 (paired t test). (C) Inhibition of the uptake of apoptotic tumor cells. Addition of the hDectin-1–specific (1→3)-β-D-glucan curdlan led to a reduction of the phagocytosis of apoptotic tumor cells (red) through immature MDCs (green). Addition of an irrelevant protein (DHFR; 10.0 μg/mL) or the buffer control (NaOH/HCl solvent of curdlan) did not affect the uptake of cellular material. Representative 2-color dot plots are shown. Percentage of double-positive cells is shown in the upper right quadrant. (D) The diagram represents mean (± SD) of 3 independent experiments. *P < .01 (paired t test).