Aproper assessment of the relative importance of impaired erythropoiesis and increased red‐cell destruction in the pathogenesis of anaemia can only be made if both erythropoiesis and red‐cell destruction can be measured simultaneously. In a previous paper (Malamos, Belcher, Gyftaki and Binopoulos, 196ia) simultaneous radioactive tracer studies of erythropoiesis and red‐cell destruction in thalassaemia were reported; in these studies, 59Fe was used to study iron utilization, haemoglobin synthesis and erythropoiesis whilst 51Cr‐labelled red cells were used to follow red‐cell survival and to identify sites of red‐cell destruction. In the present paper, the results of similar studies in sickle‐cell disease and sickle‐cell haemoglobin/thalassaemia are reported.It is recognized that the sickling phenomenon is due to the presence of an abnormal haemoglobin, haemoglobin S, in the red cells (Pauling, Itano, Singer and Wells, 1949) and that the appearance of haemoglobin S is controlled by an abnormal gene which in the homo‐zygous condition gives rise to sickle‐cell disease and in heterozygotes to the sickle‐cell trait (Neel, 1949; Vandepitte, 1954). Combinations of the gene for haemoglobin S with other abnormal genes give rise to other abnormal conditions (Neel, 1952). Important among these is sickle‐cell haemoglobin/thalassaemia, the microdrepanocytic disease of Silvestroni and Bianco (1952), in which one gene for haemoglobin S is combined with one gene for thalassaemia.A few radioactive tracer studies of erythropoiesis in these conditions have been carried out using 59Fe as tracer. Finch, Gibson, Peacock and Fluharty (1949) studied the incorporation of intravenously injected 59Fe into the circulating red cells in one case of sickle‐cell disease. They observed a rapid utilization of iron for erythropoiesis, but the fraction of the injected radioactivity appearing in the red cells was less than normal, a finding which they attributed to the rapid destruction of newly produced red cells in the circulation. Giblett, Coleman, Pirzio‐Biroli, Donohue, Motulsky and Finch (1956) also studied one case of sickle‐cell disease with 59Fe. They found an accelerated clearance of intravenously injected 59Fe from the plasma, with a plasma‐iron turnover of eight times normal; again, incorporation of the tracer into the red cells was depressed. Bothwell, Hurtado, Donohue and Finch(1957) found plasmairon turnovers of between 2.8 and 5.5 times normal in three cases of sickle‐cell disease which they investigated. All of these observations are in general agreement with the hyperplasia of bone marrow and high blood reticulocyte count observed in this disease.Red‐cell survival studies in sickle‐cell disease, whether carried out by the Ashby technique or by radioactive tracer methods, have always revealed a marked reduction in the life span of the circulating red cells. Early studies by the Ashby method of the survival of cells transfused from patients with sickle‐cell disease to normal recipients (Singer and Fisher, 1952)
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May 1, 2024
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