Expression of activation markers on NK cells and MoDCs. (A-C) Freshly isolated NK cells were cultured 40 hours in medium alone or in the presence of IL-4, IL-12, IL-2, IL-18, or a combination of these cytokines. Expression of CD56 and CD69 were analyzed by 2-color immunofluorescence (A). Values in the upper right square indicate the percentage of cells stained by both Abs. (B,C) Mean fluorescence intensity for CD56 (B) and CD69 (C). Means plus or minus SD of 3 independent experiments. (D) Induction of iDC maturation by NK cells. NK cells that had been exposed to IL-4, IL-12, IL-2, IL-18, or a combination of these cytokines for 40 hours were washed and cocultured with iDCs for 24 hours. These iDCs were then analyzed for the expression of CD86. In control cultures, iDCs were plated in medium (iDC). The mean fluorescence intensity is indicated in the right corner. Data are representative of 3 independent experiments.