Kinetics of IFN-α antiviral response by pDCs. (A) pDCs were cultured with HSV-1 or CpG A. Concentrations of IFN-α in pDC culture supernatants at different time points (4, 8, 12, 24, 36, and 48 hours) after stimulation were measured by ELISA. (B) pDCs were first cultured for 12, 24, or 36 hours with HSV or CpG A. After extensive washing, the same number of viable pDCs was restimulated with the same stimulus or with medium alone for another 12 hours. (C). pDCs were first cultured for 12 hours with medium alone. After washing, the same number of viable pDCs was then stimulated with HSV or CpG A for another 12 hours. Cells were washed again and restimulated with the same stimulus or with medium alone for 12 more hours. (D) pDCs were first cultured for 24 hours with HSV. After extensive washing, the same number of viable pDCs was restimulated with the several stimuli for the next 24 hours. The concentration of IFN-α in each supernatant was measured in duplicate by ELISA. Three independent experiments are shown as ▵, ○, and •. Flu indicates influenza virus; SeV, Sendai virus.