Apoptotic cells attenuate macrophage apoptosis. (A-D) THP-1 cells were untreated or pretreated with ACs for 16 hours. Apoptosis was induced for 8 hours with 250 μM etoposide. Viability was assessed by (A,C) annexin V/PI staining, (B,D) JC-1 staining, and subsequent analysis by flow cytometry. (C-D) Data are presented as the mean ± SD from 4 independent experiments. Differences between untreated and AC-treated cells are statistically significant and are marked with an asterisk (P < .05) for both parameters shown.