Dll4 activation of Notch signaling is critical for Dll4^hiDCs to induce IFN-γ production in CD4⁺ T cells. BALB/c Dll4^hiDCs were cultured for 5 days with B6 WT CD4⁺ T_Ns or DN-MAML CD4⁺ T_Ns. (A) Dot plots and graphs show the percentages of IFN-γ–producing and IL-17–producing cells cultured with or without addition of anti-Dll4 Ab. (B) Histograms and graphs show the percentages and mean fluorescence intensity (MFI) of cleaved ICN1 in WT CD4⁺ T cells 72 hours after Dll4^hiDC activation, with or without addition of neutralizing anti-Dll4 Ab. (C) Graphs show the relative expression of Notch target genes in WT CD4⁺ T cells after 5 days in culture. (D) Graphs show the relative expression of indicated genes in WT CD4⁺ T cells after 5 days in culture. Representative data (mean ± SD of triplicates) from 2 independent experiments are shown. *P < .05; **P < .01; ***P < .001.