Experimental AIHA in FcRγ and STIM1 wild-type and knockout mice. Transient anemia was induced in FcRγ^+/+ and FcRγ^−/− B6 mice (A,E) and in Stim1^+/+ (+/+) and Stim1^−/− (−/−) chimeras (B-D) by injection of 150 μg of the pathogenic 34-3C IgG2a mAb, and daily hematocrit was assessed (A,B). Liver H&E sections (original magnification, ×40) from 2 days anemic mice were evaluated both qualitatively (C) and quantitatively (D,E) for the occurrence of erythrophagocytosis. (F) Mice also received a lethal dose of anti-RBC 34-3C (300 μg), and survival was monitored. Results were obtained from 4 to 5 mice in each group (*P < .05, **P < .001).