Pearl mice develop transient HLH after LCMV infection independent of the presence of an additional Rab27a mutation.C57BL/6, pearl, pearl-ash^+/−, ashen, and PKO mice were infected intravenously with 200 pfu of LCMV-WE, and (A) body weight and (B) temperature were monitored daily. Dashed lines indicate the detection limit. (C) Blood counts were analyzed on d8 after infection. The white line indicates the mean, and the gray area indicates the range of values of naïve pearl mice. D8 serum levels of (D) ferritin, (E) sCD25, and (F) IFN-γ are shown. Graphs show pooled data of 2 independent experiments with 3-4 mice per group except for ashen mice, in which results from 3 mice obtained in 2 independent experiments are shown. n.s. indicates not significant (P > .05); *P < .05; **P < .01; ***P < .001.