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

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Abstract
To investigate the pathogenesis of juvenile chronic myelogenous leukemia (J-CML), the biosynthetic rates of G.gamma. and A.gamma. globin chains in the erythropoietic bursts from the bone marrow of a patient with J-CML were examined. Globin chains were labeled with 14C-labeled amino acids, separated by isoelectric focusing and quantitated by fluorography. Synthesis of .gamma.-chains in the erythropoietic bursts comprised 89.0% of the total non-.alpha.-chains. The G.gamma.:A.gamma. ratio was 0.67, which is within the ratios obtained in newborns. Individual erythropoietic bursts contained varying ratios of both .gamma. and .beta. chains and all revealed more G.gamma. than A.gamma. chain synthesis. The relative proportions of G.gamma. and total .gamma. 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 .gamma./(.gamma. + .beta.) and G.gamma./(G.gamma. + A.gamma.) approached normal frequency distributions. 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 G.gamma.:A.gamma. ratio has not occurred, rather than by the abnormal proliferation of an F-cell clone.