CD8⁺ T cells and the action of caspases are necessary for the suppression of antigen presentation by endogenous DCs after viral infection. (A) Six days after LCMV infection, splenic DCs were sorted from WT or prf^−/− mice that were treated with either the pan-caspase inhibitor Q-VD-OPH or the carrier (dimethylsulfoxide) on day 5 and cultured as above with LCMV-specific CD8⁺ T cells at the indicated ratios. IFN-γ production was measured by ELISA after overnight culture. (B) Six days after LCMV infection, splenic DCs were sorted from WT and RAG^−/− mice given either CD8-depleting antibody or an isotype control antibody. DCs were cultured with LCMV-specific CD8⁺ T cells. IFN-γ production was measured by ELISA after overnight culture. *P < .005.