LCMV-infected pfp^–/– mice display striking elevations of serum cytokine levels. Serum cytokine levels from either wild-type or pfp^–/– mice infected with LCMV are shown. All assays were performed on sera obtained 12 days after infection, except IFNα, which was assayed on sera from mice infected 6 days previously. Data (± standard error) are representative of at least 2 experiments with at least 3 mice in each group.