Serum CD26/DPP‐4 activity, hematopoietic cell populations, and surface expression of CD26/DPP‐4 during acute liver injury. (A) DPP‐4 activity in the serum of C57BL/6 control (PBS‐treated) and APAP‐treated mice analyzed at 24 hours and 72 hours (depicted in arbitrary units, representing the rate of substrate decay during the enzymatic assay normalized to the average value of the controls; right axis, filled triangles linked by dashed line) was superimposed on (B) the proportion of Kupffer cells (F480highMac1+Ly6c‐CD45+ cells), (C) the proportion of CD45+ cells in the liver, and (D) the proportion of blood monocytes (Ly6c+ among CD45+ cells) as well as (E) the median fluorescent intensity of CD26/DPP‐4 on Kupffer cells, (F) on liver CD45+ cells, and (G) on blood monocytes (left axis, empty squares linked by straight line). Mean values and SDs are represented; *P <0.05, **P <0.01, ***P <0.001, and ****P <0.0001 in one‐way analysis of variance using Tukey's correction. Plots represent one of three independent experiments, n = 3‐4 mice/group. Abbreviations: A.U., arbitrary units; MFI, mean fluorescent intensity.