Spontaneous apoptosis of blood dendritic cells (DCs) in patients with breast cancer. Peripheral blood mononuclear cells isolated from patients with breast cancer (stage I to II; n = 13) and age-matched healthy volunteers (n = 15) were analyzed for apoptosis by flow cytometry. (a)In order to include all apoptotic cells and avoid debris, gating was set to include only 7-AAD negative events (R1) which were then visualized and re-gated on forward (FSC) and side scatter (SSC) characteristics (R2). Within this mononuclear cell population, blood DCs were identified as lineage negative HLA-DR positive cells (R3). Representative dot plots are shown. (b)Apoptosis in blood DCs from patients (black) and healthy volunteers (grey) was determined by two different methods, Annexin-V binding and TUNEL assays. In all experiments, each patient was tested in parallel with at least one healthy volunteer. Representative histograms are shown. (c)Summary of apoptosis data. The proportions of Annexin-V+ and TUNEL+ blood DCs estimated for all patients (black) and healthy volunteers (grey) are shown accordingly. Error bars indicate the standard error of the mean. Statistically significant differences between controls and patients are indicated as: *, p < 0.05; **, p < 0.01.