Changing erythrocyte populations in juvenile chronic myelocytic leukemia: evidence for disordered regulation

Fetal and adult erythrocyte characteristics were studied serially in a 30 mo old female with juvenile chronic myelocytic leukemia. On presentation the erythrocytes exhibited predominantly fetal characteristics as indicated by 69% hemoglobin F (HbF), 1.1% hemoglobin A₂ (HbA₂), absent 1 antigen, and fetal levels of the erythrocyte enzymes, carbonic anhydrase I and II, glucose 6 phosphate dehydrogenase, hexokinase, pyrivate kinase, and lactate dehydrogenase; 100% of the erythrocytes present contained HbF. However, Orskov Jacobs Stewart hemolysis demonstrated that at least one adult characteristic was present. Seven months later HbF was 17%; I antigen and carbonic anhydrase I had increased to adult levels. The number of cells containing HbF had decreased to 30%. Further studies indicated that at least three new populations of red cells were present after 7 mo which had not previously been detected. Two of these populations exhibited a mixture of both fetal and adult characteristics. Such findings suggested that an ongoing disturbance of regulatory mechanisms was responsible for the variable expression of fetal versus adult erythrocyte characteristics.