Erythropoietic activity and storage iron levels in hypertransfused and hypotransfused CA mice. (A) Erythroid progenitors in the bone marrow of untransfused CA mice, wild-type controls, and transfused CA mice were determined by flow cytometry analysis of Ter119 and CD71 stained bone marrow cells. Dead cells and transfused GFP⁺ RBCs were excluded from analysis by using the 7AAD⁻ and GFP⁻ populations, respectively. Percentages of Ter119⁺ erythroid cells are shown. Untransfused and hypotransfused CA mice had increased erythropoietic activity compared with control, whereas hypertransfused CA mice had reduced erythropoietic activity. All mice were 8 weeks of age, except the untransfused CA mice, which were only 2 weeks old. (B) Storage iron concentrations in livers and hearts were quantified in male and female CA mice after 8 weeks of transfusion. Compared with littermate control γβ^A/γβ^A mice, the storage iron in the livers of both hyper- and hypotransfused CA mice increased significantly (P ≤ .0001). There was no significant increase in the hearts of either transfused group. P values were calculated by 2-tailed unpaired Student t test, n ≥ 5 in each group.