Acetylation of human fetal hemoglobin occurs throughout erythroid cell maturation

Abstract

The biosynthesis of human acetylated fetal hemoglobin (Hb F 1) has been examined by incubating the following cell types with [ 3H]leucine: (a) burst-forming unit erythroid cells cultured from umbilical cord mononuclear cells, (b) infant bone marrow, (c) umbilical cord blood, and (d) peripheral blood cells from adults with elevated fetal hemoglobin. Newly synthesized Hb F 1 was 18–20% that of Hb F 0 in burst-forming unit erythroid cells which were immature, mature, or in an intermediate state of development. In infant marrow and in infant and adult peripheral blood the extant Hb F 1 comprised 10.8 ± 1.8 of the total Hb F. In marrow cells the specific radioactivity (cpm/mg) of Hb F 1 was 1.4–2.0-times greater than that of Hb F 0. In peripheral blood cells these ratios were slightly greater. [ 3H]Leucine-labeled infant bone marrow, umbilical cord blood, and adult peripheral blood cells were subjected to density gradient ultracentrifugation. The ratio of specific radioactivity for Hb F 1/Hb F 0 increased from 1.0–1.8 in the lightest cell zone to 5.2–9.0 in the more dense cells. Thus the biosynthesis of Hb F 1 is enhanced in cells which are more mature than those responsible for the bulk of hemoglobin synthesis, and the acetylation of Hb F provides a marker of erythroid cell maturation.