PD-1 KO mice develop pulmonary edema and severe hypotension. (A) Wet/dry weight ratios of whole lungs from WT and PD-1 KO mice were determined on day 6 after 106 pfu LCMV docile infection. n = 3–4 mice per group. Means ± SEM from one representative of two experiments are shown. (B and C) Total protein concentrations (B) and albumin concentrations (C) were determined in the BAL supernatant of naive and infected WT and PD-1 KO mice on day 6 p.i. Infected, n = 6–7 mice per group; naive, n = 1 mouse per group. Means ± SEM from two pooled experiments are shown. (D and F) Photos were taken of nonperfused, PFA-fixed lung lobes (D) and H&E-stained lung sections (F) from WT and PD-1 KO mice on day 6 after infection. Photos from representative mice from one of two experiments are shown. Bars, 150 µm. (E) Albumin concentrations were determined in the BAL supernatant of untreated and αPD-L1–treated WT and PKOB mice on day 6 p.i. Treated, n = 7–8 mice per group; untreated, n = 3 mice per group. Means ± SEM from two pooled experiments are shown. (G) O2 saturation and lactate concentration in arterial blood were measured in WT and PD-1 KO mice on day 6 p.i. n = 4 mice per group. Means ± SEM from one representative of two experiments are shown. n.s.: not significant. (H) Mean arterial blood pressure was determined in WT and PD-1 KO mice on day 6 p.i. n = 4 mice per group. Means ± SEM from one representative of two experiments are shown. (I) Blood pressure was determined in WT, αPD-L1–treated WT, PD-1 KO, and CD8 T cell–depleted PD-1 KO mice between days 4 and 6 after infection. n = 4 mice per group. Means ± SEM are shown. **, P < 0.01 (unpaired two-tailed Student’s t test).
