Regulation of Fetal and Adult Hemoglobin Formation in Patients with Sickle Cell Disease Transfused to Normal Hematocrits

Two patients with sickle cell anemia and one patient with sickle thalassemia were acutely transfused to normal hemoglobin levels. The synthesis of fetal and adult (in this instance, Hb S) hemoglobins was assessed in cohorts of reticulocytes emerging during the period of erythroid suppression which followed. In two patients observations were also made during the period of recovery from the suppression. Hemoglobin synthesis in the reticulocytes was assessed by means of in vitro incorporation of C¹⁴-labeled leucine into the separate hemoglobins. The results in all three patients suggested that both fetal and adult hemoglobin synthesis are under similar physiologic control mechanisms during short-term alterations in the state of erythropoiesis; the formation of both was almost completely stopped soon after transfusion, and both were almost simultaneously reactivated as the patients returned to the anemic state.