The Distribution of Hemoglobin Types in Thalassemic Erythrocytes*

Abstract

The distribution of hemoglobin and of the various hemoglobin types was studied after differential centrifugation of the red cells in [beta]-thalassemia homozygotes and in the association of [beta]-thal-assemia with other hemoglobin abnormalities. Cells of the bottom layer have a significantly higher mean corpuscular hemoglobin, a significantly higher percentage of hemoglobin F and, hence, a considerably higher mean absolute amount of fetal hemoglobin per cell than those of the top layer. The differences in the absolute amounts of the non-fetal hemoglobins (hemoglobins A and A2) per cell between the 2 layers are not significant. Increments of mean corpuscular hemoglobin and mean corpuscular fetal hemoglobin from the top to the bottom layer showed good correlation. The findings suggest that the content of hemoglobin in the red cells of thalassemia depends to a large extent on the capacity of the cells to synthesize the [alpha]-chains of hemoglobin F in addition to the genetically determined level of [beta]-chain synthesis. The capacity for such compensation differs from cell to cell and from case to case; it does not appear to be an automatic result of the presence of the thalassemia genes, but it is of importance for the survival of the red cells in the circulation.