Apoptosis in blood dendritic cells (DCs) is induced by breast tumor-derived supernatants. (a)Apoptosis in blood DCs was determined by Annexin-V binding and TUNEL assays following culture (24 h) in the presence of 50% (v/v) peripheral blood mononuclear cell (PBMC)-derived supernatant (PBMC-SN) or tumor-derived supernatants (TDSN; MCF7, MB435, MA11 and SKBR3). Representative dot plots (SSC on y-axis versus apoptosis on x-axis) are shown with numbers indicating the percentage of apoptotic cells. (b)Summary of apoptosis data. The proportions of Annexin-V+ and TUNEL+ blood DCs represent the average ± standard error of the mean of five independent experiments for which statistically significant differences compared to PBMC-SN are shown: *, p < 0.05; **, p < 0.01; ***, p < 0.001. (c)For morphological analyses (original magnification times 1,000), 50 cells were assessed in three separate fields. In contrast to PBMC-SN, cultures incubated with TDSN (MA11) frequently demonstrated features of apoptotic death in blood DCs (reduction in cell volume and nuclear size, cytoplasmic blebbing, cell membrane convolutions and formation of apoptotic bodies). Three independent experiments with similar findings were performed.