Impaired apoptotic cell uptake and cross-presentation by CD8⁺ DCs in CD11c-Rac1(N17) mice. (A) Tg⁺ mice and WT controls were injected with 1 × 10⁷ CFSE-labeled allogeneic (BALB/c) B cells, and spleens were harvested 14 hours later. Following collagenase/DNase digestion, splenocytes were stained with mAb specific for CD11c and CD8α. Dot plots are gated on CD11c^hi cells, with CFSE labeling and CD8 staining as indicated. The frequencies of CFSE⁺ cells among all DCs (CD11c^hi) and CD8⁺ DCs are shown (mean ± SD, n = 3). Data are representative of 2 independent experiments with similar outcome. (B) CFSE-labeled OT-1 cells (1 × 10⁶) were transferred into Tg⁺ mice and WT controls, followed by injection of 1 × 10⁶ OVA- or BSA (control)–loaded β₂m^-/- cells 1 day later. Spleens were harvested 3 days after the second injection, digested with collagenase/DNase, and stained with anti-CD8α mAb, H2-K^b/SIINFEKL tetramers, and PI. Dot plots are gated on CD8⁺ cells, with CFSE labeling and tetramer staining as indicated. Histogram analysis of CFSE⁺ OT-1 cells is shown as inserts in the dot plots. Total numbers of OT-1 (K^b/SIINFEKL tetramer-positive) cells per spleen (upper graph) and OT-1 cells per cell division (lower graph) were calculated; the mean (± SD) is shown for 3 mice per group (BSA, n = 2). Results from one experiment are shown and are representative 3 independent experiments performed.