The relative rates of incorporation of Fe59 into heterogenic hemoglobins was studied in four patients with sickle cell trait. Three of the patients were free of superimposed disease, while one had active pulmonary tuberculosis. In all subjects there was a significantly greater incorporation of radioiron, per milligram of hemoglobin, into hemoglobin S than into hemoglobin A.
The data indicate that in sickle cell trait the rates of synthesis of the heterogenic hemoglobins are not proportional to their circulating concentrations. Two interpretations appear possible. Since the size of the intra-marrow pool of hemoglobin S was not known, it is possible that there exists a smaller preformed pool of the abnormal hemoglobin, with the isotope making its appearance first in hemoglobin S. However, it is also possible that hemoglobin S is synthesized at a rate which is greater than that reflected by its circulating concentration. This implies that the relative concentrations of hemoglobin S and hemoglobin A vary from erythrocyte to erythrocyte, and that those cells with the greatest proportion of hemoglobin S are selectively destroyed.