Activin-A production by DCs. Immature MoDCs (A-C) or purified CD1c⁺ DC (D-E) or CD123⁺ PDCs (F) were cultured in 96-well plates for 2 to 72 hours (MoDCs) or 2 to 24 hours (CD1c⁺ DCs) or 24 hours (CD123⁺ PDCs) in either serum-containing or serum-free culture medium alone or with the indicated stimuli. Supernatants were collected and assayed for activin-A. Data represent the mean plus or minus 1 SD of 3 separate donors or individual donors are shown. Gray shaded area in panel F indicates the assays level of sensitivity. *P ≤ .01, **P ≤ .05 versus medium alone.