Kinetics of MHC II intracellular pool constitution in flu-stimulated pDCs. (A) Purified pDCs were activated by flu in the presence or the absence of CHX (10 μg/mL) for the indicated periods of time. Then, pDCs were stained for MHC II and analyzed by 3-dimensional deconvolution microscopy. White crosses represent the zone of the captured images, which was subjected to the deconvolution process. Equatorial zones of 3-dimensional reconstructions are presented. Scale bar represents 3 μm. (B) Percentage of pDCs exhibiting an intracellular pool of MHC II as seen in panel A were estimated as described in Figure 2. n.d. indicates not determined because long exposure to CHX affected cell viability. Error bars represent SD. (C) Levels of expression of peptide-bound MHC II by pDCs exposed to flu and treated or not with CHX were determined by flow cytometry as in Figure 1B. Results presented are representative of 3 independent experiments.