A patient heterozygous for the X-linked enzyme glucose-6-phosphate dehydrogenase and with Philadelphia chromosome-positive chronic myelogenous leukemia (CML) was treated with combination chemotherapy and had a partial loss of Philadelphia chromosome accompanied by partial restoration of nonclonal hematopoiesis as determined by glucose-6-phosphate dehydrogenase. Studies of in vitro hematopoiesis were performed after chemotherapy to evaluate the influences of neoplastic stem cells on normal cells and to determine whether there were physical and cell kinetic differences between leukemic stem cells and their normal counterparts. The data revealed the following: (a) The frequencies of normal committed granulocytic stem cells (CFU-C) and erythroid stem cells (BFU-E) in blood did not differ from the frequencies in marrow. (b) Normal late erythroid progenitors (CFU-E) were found at a significantly lower frequency that the more primitive BFU-E. Calculations indicated that not only was there a decrease in CFU-E production by normal BFU-E, but there was also abnormal clonal expansion of CML BFU-E (CFU-E:BFU-E ratio for normal progenitors was 1.1, whereas for the CML clone it was 11.5). (c) No increase in frequency of normal CFU-C was found after marrow cells were exposed to high specific activity tritiated thymidine. (d) Normal CFU-C and those from the CML clone were not separable on the basis of density. (e) The frequency of normal BFU-E was consistently greater than that of CFU-C, suggesting that regulatory differences influence the commitment of normal progenitors to the two pathways.
J W Singer, J W Adamson, Z A Arlin, S J Kempin, B D Clarkson, P J Fialkow