pDC are highly sensitive to GC-induced apoptosis and are not rescued by TLR-independent stimuli. Cell viability of freshly isolated pDCs cultured 24 hours in the presence of different GC concentrations (10−4 to 10−8M; A), in association or not with IL-3 (10 ng/mL; B), or with GM-CSF (100 ng/mL; C) were assessed by trypan blue dead cell exclusion. Apoptotic and necrotic cells were quantified by flow cytometry using an annexin V/PI staining. The percentage of cells in each dot plot indicates double-negative viable pDCs (bottom left quadrant) in the presence of various GC concentrations (10−4 to 10−8M) associated to the addition of IL-3 (10 ng/mL; D) and GM-CSF (100 ng/mL; E). Histograms represent the mean ± SD of at least 3 independent experiments. P values were determined using 2-tailed Student t test (NS, not significant; *P < .05; **P < .01).
