The effects of blocking endogenous activin-A with follistatin on E coli or CD40L-mediated IL-10 production by MoDCs. Immature MoDCs were cultured in 96-well plates for 24 hours with either GM-CSF and IL-4 alone or with E coli (A) or CD40L (B) in the absence or presence of increasing concentrations of follistatin. Supernatants were collected at the various times indicated and assayed for IL-10 production by ELISA. Data represent the mean plus or minus 1 SD of 3 separate donors (**P ≤ .02 vs CD40L only). MoDCs stimulated with CD40L in the presence of increasing concentrations of follistatin were lysed, mRNA extracted at times indicated, and IL-10 qRT-PRC performed (C). One of 2 donors is shown.