TLR-induced IFN-α and TNF-α synergize for the protection of pDCs from GC-induced apoptosis. (A-B) Overnight IFN-α and TNF-α production by purified pDCs (105 cells/well) from healthy blood donors was assessed in the presence of Flu or CpG-C in association with GC (10−4 and 10−6M). IFN-α and TNF-α productions were inhibited by pharmacologic, but unaffected by stress-induced, GC levels. (C) Viability of pDCs cultured overnight with GC at 10−4M in the presence of TLR-7 ligand (Flu) or with recombinant cytokines (IFN-α, IL-3, and TNF-α). (D) Viability of pDCs cultured overnight with GC at 10−4M and TLR-7 ligand (Flu) in the presence of IFN-α and TNF-α blocking antibodies. (E) Viability of pDCs cultured overnight with GC at 10−4M and TLR-9 ligand (CpG-C) in the presence of IFN-α and TNF-α blocking antibodies. 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; ***P < .001).
