Accumulation of heterozygous mutations in HLH-causing genes induces biological parameters of HLH after LCMV infection. Control (black bars), Prf1^−/− (lightest gray bars), Rab27a^+/−Stx11^+/− (AS, light gray bars), Rab27a^+/−Prf1^+/− (AP, medium gray bars), and Rab27a^+/−Prf1^+/−Stx11^+/− mice (ASP, dark gray bars) were infected with 200 PFU of LCMV-WE. (A) Serum IFN-γ on day 8 postinfection. (B) Serum IL-6 (left) and TNF-α (right) on day 14 postinfection. (C) MNC infiltration in liver on day 14 postinfection. (D) The percentage of CD8⁺ among all MNCs from the liver. (E) Fluorescence-activated cell sorter (FACS) analysis of MNCs from liver cells gated on CD3⁻ CD19⁻ NK1.1⁻ (left). Quantification of absolute numbers of CD64⁺ Ly6C⁺ in liver on day 14 postinfection (right). (F) ASAT on day 14 postinfection. (G) ALAT on day 14 postinfection. (H) Serum LDH on day 14 postinfection. Data (mean ± SEM) are representative of 3 to 4 independent experiments with at least 3 mice in each group. *P < .05; **P < .01; ***P < .001; ****P < .0001. ALAT, serum alanine aminotransferase; ASAT, serum aspartate aminotransferase; LDH, lactate dehydrogenase.