DIgR2 negatively regulates the ability of DCs to prime Ag-specific T-cell responses. siRNA-transduced DCs were pulsed with OVA-II peptide (323-329), matured with LPS stimulation, and then cocultured with DO11.10 T cells. (A) Proliferation of T cells. (B) Cytokine production by T cells. (C) Percentages of IFN-γ⁺ T cells in the gated CD4⁺ T cells quantitated by double-staining of IFN-γ and CD4, with brefeldin A present in the coculture. (D) Percentages of IL-12p70⁺ DCs in the gated CD11c⁺ DCs quantitated by double-staining of IL-12 and CD11c. (E) IL-12p70 production quantitated by ELISA analysis. (F) Reduced ability of DIgR2-siRNA-DCs to prime Ag-specific T-cell responses in vivo. DO11.10 T cells were transferred, together with OVA-pulsed DCs one day later, into recipient mice; after 5 days, collected splenocytes were harvested and double-stained with CD4-FITC and KJ1-26-PE for flow cytometry. The numbers in CD4-gated plots indicate percentage of DO11.10 cells (KJ1-26⁺) among total CD4⁺ T cells. Data represent 1 of at least 3 experiments with similar results. ^*P < .01 and #P < .05 versus DIgR2-mut-siRNA-DCs. Error bars indicate SE.