Perforin and nonhematopoietic H-2D^b expression are required for pathology development. (A and B) Core temperatures were measured in WT mice, PD-1 KO mice, and αIFN-γ + αTNF–treated PD-1 KO mice (A) or αIL-6R + αTNF-treated PD-1 KO mice (B) after 10⁶ pfu LCMV docile infection. (C) Core temperatures were monitored in untreated WT and PKOB mice and in αPD-L1–treated WT and PKOB mice after infection. A–C: n = 3–4 mice per group. Means ± SEM from one representative of two experiments are shown. **, P < 0.01 (unpaired two-tailed Student’s t test). (D) WT→WT and WT→H-2D^b KO chimeric mice were transferred with 2.5 × 10⁴ PD-1^−/− P14 cells, followed by 10⁶ pfu LCMV docile infection and monitoring of core temperature. WT→WT, n = 9 mice per group; WT→H-2D^b KO, n = 12 mice per group. Means ± SEM from two pooled experiments are shown. **, P < 0.01 (unpaired two-tailed Student’s t test).