In vivo administration of rapamycin inhibits endocytosis by Flt3 ligand–expanded splenic DCs.

(A-C) DCs were expanded in vivo with Flt-3 ligand and animals were injected with either rapamycin or vehicle, as described in “Study design.” Endocytotic activity was measured by analyzing FITC-albumin uptake at 37°C and 4°C (negative control) and relative MFI in comparison with animals injected with vehicle only. Results are representative of 8 animals per group and were obtained in 5 independent experiments. Differences between the groups were compared by the 2-tailed Student t test for independent samples. Similar findings were obtained with respect to FITC-dextran uptake, as described in “Results and discussion.”