Plg deficiency diminishes IgG-mediated erythrocyte phagocytosis in vivo.Plg^+/+ and Plg^−/− mice were injected intraperitoneally with anti-mouse RBC mAb 34-3C to induce experimental autoimmune hemolytic anemia. (A) Hematocrits in mice 3 days after injection of PBS or anti-RBC mAb 34-3C. Bars are mean ± SD from 4 mice per group. (B) Microscopic images (original magnification, ×20) of liver sections stained either with Prussian blue ([a-d] duplicates from 2 different mice of each genotype or H&E [e-f]). Images taken at a ×20 original magnification were captured at room temperature under Leica DM5500B upright microscope using either an α Retiga SRV Cooled CCD camera for Prussian blue images or with a Leica DFC425C camera for H&E images. Staining with Prussian blue reflects the iron deposits in Kupffer cells derived from phagocytosed erythrocytes. H&E staining shows hematopoietic foci (black arrows) and phagocytosed RBCs (arrowheads) in Plg^+/+ and Plg^−/− liver. Images are representative of 4 mice per group. (C) Quantification of Prussian blue stain in liver sections derived from Plg^+/+ or Plg^−/− mice. (D) Quantification of RBCs in liver sections derived from Plg^+/+ or Plg^−/− mice. Bars are mean ± SD of average area of Prussian blue or RBCs per microscopic field. Three to 5 microscopic fields were quantified from 4 mice per group.