Analysis of BFU-E expansion during the recovery from PHZ-induced acute hemolytic anemia. (A) Bone marrow and (B) spleen BFU-Es from C57BL/6-f/f (▪), C57BL/6-f/+ (▦), and C57BL/6-+/+ control mice (□) during the recovery from PHZ-induced acute anemia. Cells were plated in methylcellulose media containing Epo (3 U/mL) and IL-3 (10 ng/mL). (C) Bone marrow and (D) spleen BFU-Es from C57BL/6-f/f, C57BL/6-f/+, and C57BL/6-+/+ control mice during the recovery from PHZ-induced acute anemia. Cells were plated in methylcellulose media containing only Epo (3 U/mL). (E) Sensitivity of bone marrow and spleen BFU-Es to Epo. A total of 5 × 10⁵ bone marrow or spleen cells were plated in methylcellulose media containing the indicated concentrations of Epo plus 50 ng/mL SCF (bone marrow, ▪) or 15 ng/mL BMP4 (spleen, □). The asterisk indicates P = .02. Error bars represent standard deviation.