Ik^−/− DCs show enhanced Notch signaling. (A) DCs were harvested from Ik^−/− or WT B6 animals (n = 3-5 mice/group) and analyzed by Q-PCR for constitutive expression of Notch receptors (Notch1-3) and their ligands (Jagged-1 and Jagged-2). (B) Notch target genes, Hes1, Deltex1, and pTa, in BMDCs and splenic DCs. Data are from 1 of 3 different experiments. (C) DCs from B6 WT, Ik^−/−, and IkDN^+/− animals were pretreated with DAPT for 12 hours and then used as stimulators in an MLR with T cells from syngeneic B6 or allogeneic BALB/c animals. Proliferation was determined by ³H-thymidine incorporation at 96 hours. Data are means ± SEM of quadruplicate cultures. Results are from 1 of 3 similar experiments. (D) T cells from CD4-Cre DNMAMAL animals were used as responders with BALB/c BMDCs that were pretreated with DAPT or control. Proliferation was determined by ³H-thymidine incorporation at 96 hours. Data are means ± SEM of quadruplicate cultures. Results are from 1 of 2 similar experiments.