In vivo administration of RAPA promotes IL-4 hyporesponsiveness of DCs and suppresses TNF-α production. Animals were treated with RAPA (▴) or vehicle (plus Flt3L, 10 days; ▪). Splenic DCs were purified by density gradient centrifugation and immunomagnetic bead sorting and stimulated with LPS for 24 hours. (A-B) Titration of the effect of IL-4 (in the presence of LPS) on the production of bioactive IL-12p70. Mean IL-12p70 production (± 1 SD) by DCs from mice given RAPA for 7 days (A) and 10 days (B) versus drug vehicle-injected controls (3 animals/group). (C) Effect of RAPA on TNF-α production. Mean TNF-α production (± 1 SD) by DCs from animals that received RAPA for 10 days versus drug vehicle-injected controls (3 animals/group). *P < .05 versus vehicle (2-tailed Student t test).