LCMV-infected Stx11^−/− mice display clinical and laboratory features of HLH.Stx11^+/− (○), Stx11^−/− (●), PKO (), and wild-type B6 () mice were infected with 200 PFU LCMV-WE intravenously. (A) Body weight and peripheral body temperature were monitored daily. (B-D) Peripheral blood cell counts (B), liver enzymes, ferritin levels, triglycerides (C), as well as serum sCD25 levels (D) were analyzed on day 12 after infection. (E) On day 12, these mice and noninfected (n.i.) B6 mice were assayed for splenomegaly. (F) Representative pictures of liver sections of day 12 LCMV-infected Stx11^−/−, PKO, and B6 mice stained with anti-F4/80 (left 10×; right 40×). Bottom right graph: Semiquantitative analysis of hemophagocytosis by macrophages as assessed in 10 high power visual fields (40×) of a defined area (97 656 μm²) per mouse. Scale bars represent 100 μm and 20 μm, respectively. Horizontal lines in graphs represent mean values. Data (mean ± SEM) represent 3 independent experiments with at least 3 mice per group. *P < .05 (Student unpaired t test). **P < .005 (Student unpaired t test). ***P < .001 (Student unpaired t test). n.s. indicates not significant.