Because all erythroid cells in chronic myelogenous leukemia are believed to arise from a common pluripotent stem cell, we studied the cellular distribution of fetal hemoglobin in patients with the disease to test whether cells with and without hemoglobin F have a common or separate pluripotent stem-cell origin. In a patient with chronic myelogenous leukemia and sickle/beta thalassemia, 17 per cent of the red cells during remission and 18 to 22 per cent during the blastic phase contained fetal hemoglobin. In 24 non-hemoglobinopathic leukemic patients 0.3 to 28 per cent of red cells contained hemoglobin F. Since the erythrocytes in chronic myelogenous leukemia are almost exclusively derived from the malignant clone, these data suggest that cells containing fetal hemoglobin originate from the same pluripotent stem-cell progenitor as those without hemoglobin F. The findings argue against a separate line of "partially switched" pluripotent stem cells as being responsible for maintenance of hemoglobin F production in the adult.
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