Rapamycin inhibits endocytosis by GM-CSF+IL-4–expanded DC.

(A-D) BM-derived DCs were expanded for 7 days as described in “Study design”; rapamycin (Rapa) was added at day 2 (± FK506) at the concentrations indicated. FITC-albumin and FITC-dextran internalization at 37°C and 4°C (negative control), MHC class II (IA^b β-chain), and CD11c expression were analyzed by flow cytometry. In all experiments, CD11c⁺ cells were analyzed to determine endocytosis and MHC class II expression specifically in DCs. (A-C) Numbers indicate the percentage of CD11c⁺ cells that were positive for the marker indicated. (D) Data represent mean values (± SE) of CD11c⁺ cells after subtraction of background fluorescence (4°C). (E) Comparison of total cell and DC numbers on day 7 of culture. (D, E) Differences between paired cultures were compared by 2-tailed Student t test for paired samples (*P < .05 vs control; ♦ P < .05 vs Rapa 1). (A-D) Results are representative of 4 (FITC-dextran) and 6 (FITC-albumin) separate experiments. (E) Results are representative of 6 separate experiments.