Analysis of the spleen under basal conditions and after acute hemolysis.

(A) Spleen/body weight percent in wild-type, Hp-null, Hx-null, and HpHx dKO mice subjected to φhyd-induced hemolysis. Mice were injected with 0.15 mg/g body weight of φhyd. Values represent means ± SEM. At least 5 animals at each time point were analyzed. Differences between wild-type and HpHx dKO mice were significant at each time point (P < .001). Differences between wild-type and single KO mice became significant from day 2 (P < .001). (B) Spleen sections of 2 wild-type (i,iii,v) and 2 HpHx dKO (ii,iv,vi) mice before (i-ii) and one day after φhyd injection (iii-vi) stained with hematoxylin and eosin (i-iv) and processed by immunohistochemistry with an anti–HO-1 antibody (v-vi). Note the stronger red blood cell accumulation in the HpHx dKO mouse than in the wild-type mouse after φhyd treatment, but no differences in HO-1 expression. Scale bars: i-iv, 250 μm; v-vi, 200 μm.