NK cells cocultured with LPS-stimulated MDDCs are more efficient in promoting IFN-α release by pDCs. Freshly isolated NK cells from 2 different donors (A-B) were cultured with allogeneic iMDDCs in the presence of LPS for 18 hours. Then NK cells were negatively separated from MDDCs by immunomagnetic depletion and cocultured with autologous pDCs in the presence of CpG-A (5 μg/mL). Either resting NK cells or short-term IL-12–activated NK cells were comparatively cocultured with pDCs. After 24 hours of culture, supernatants were collected and analyzed for IFN-α concentrations by specific ELISA. The NK/pDC ratio was 10:1.