Shiro Kasai

Characterization of the erythropoietic precursors (BFU‐E) in a patient with juvenile chronic myelogenous leukaemia by the analysis of Gγ and Aγ globin chains

Summary. In order to investigate the pathogenesis of juvenile chronic myelogenous leukaemia (J‐CML) we examined the biosynthetic rates of Gγ and Aγ globin chains in the erythropoietic bursts from the bone marrow of a patient with J‐CML. Globin chains were labelled with 14C‐labelled amino acids, separated by isoelectric focusing and quantitated by fluorography. The synthesis of γ‐chains in the erythropoietic bursts comprised 89·0% of the total non‐α‐chains. The Gγ: Aγ ratio was 0·67, which is within the ratios obtained in newborns. Furthermore, individual erythropoietic bursts contained varying ratios of both γ and β chains and all revealed more Gγ than Aγ chain synthesis. The relative proportions of Gγ and total γ chain biosynthesis in 62 separate erythropoietic bursts were 0·69·0·06 and 0·86·0·06, respectively. Cumulative frequency distributions of individual bursts differing in the ratios of γ/(γ+β) and Gγ/(Gγ+Aγ) approached normal frequency distributions. These results suggest that the levels of Hb F in J‐CML are controlled by qualitative changes in a single population of erythropoietic precursors, in which normal switching of the Gγ:Aγ ratio has not occurred, rather than by the abnormal proliferation of an F‐cell clone.