DC numbers and function in WT and prf^−/− mice after LCMV infection are shown. (A) Splenic DCs (CD11c⁺/major histocompatibility class II⁺ cells) were quantitated in uninfected WT mice, LCMV-infected (day 6) WT, and prf^−/− mice (day 6). (B) Splenic DCs were sorted from WT or prf^−/− mice 6 days after LCMV infection and cultured with LCMV-specific (P14) or ovalbumin-specific (OT1) CD8⁺ effector T cells at the indicated ratios. IFN-γ production was measured by ELISA at 24 hours. (C) Splenic DCs were sorted from WT and prf^−/− mice at the indicated times after LCMV infection and cultured at a fixed ratio (0.4:1, DC/T cell) with LCMV-specific effector T cells. Data are presented ± standard error. *P < .001. N.S., not significant.