DC interaction with apoptotic cell fragments. DCs were exposed to different amounts of apoptotic Jurkat cells stained with CMTMR. DCs having internalized apoptotic cells (CMTMR⁺ DC) were detected by confocal or FACS analysis, before (total DC) or after (migrating DC) migration in response to CCL21. (A) Confocal pictures of total or migrating ApoC-loaded DCs at a 1:4 ratio. DCs loaded with CMTMR-labeled apoptotic cells (red) were stained with CD11-APC (green) and DAPI (blue), deposed on a microscope slide, and fixed in 2% paraformaldehyde (PFA). Arrows point to discrete intracellular accumulations of CMTMR-labeled apoptotic cell fragments in the cytosol of DCs. Fields represent 175 × 250 μm and 70 × 100 μm for 40 × and 100 × objective magnifications, respectively. (B) Representative FACS histograms under conditions similar to those in panel A. Solid and dashed lines represent fluorescence of DCs incubated with or without CMTMR-stained apoptotic cells, respectively. (C) Percentages of CMTMR⁺ DCs (total and migrating) as a function of the DC/ApoC ratio were determined from FACS profiles in panel B, above a CMTMR fluorescence intensity of 2 × 10.¹