Analysis of Hb accumulation and HO-1 expression in the liver after acute hemolysis.

(A) Liver sections of 2 wild-type (i,iii) and 2 HpHx dKO (ii,iv) mice one day after φhyd (i-ii) or Hb (iii-iv) injection processed by immunohistochemistry with an anti-Hb antibody. Note Hb accumulation in Kupffer cells of both wild-type and HpHx dKO mice. Scale bars = 100 μm in all subpanels. (B) Liver sections of a wild-type (i) and an HpHx dKO (ii) mouse one day after φhyd injection processed by immunohistochemistry with an anti–HO-1 antibody. Note the higher number of HO-1–expressing cells in the HpHx dKO mouse than in the wild-type mouse. Scale bars = 100 μm in both subpanels. (C) Number of HO-1–positive cells per microscopic field: cells were counted as reported in “Materials and methods.” At least 4 animals per genotype at each time point were analyzed. *P < .01, **P < .001. (D) Percent of Kupffer cells expressing HO-1: consecutive liver sections were stained with the anti-F4/80 or anti–HO-1 antibodies, and positive cells were counted as reported in “Materials and methods.” At least 3 animals per genotype at each time point were analyzed. *P < .01; **P < .001.