Growth of CD34+ acute myeloblastic leukemia colony-forming cells in response to recombinant hematopoietic growth factors.
In order to minimize the interactions of clonogenic cells with accessory cells and characterize the direct effect of recombinant hematopoietic growth factors (HGF) on acute myelogenous leukemia colony-forming cells (AML-CFU), the response of CD34+ AML-CFU to individual or combined recombinant HGF, i.e., interleukin-1 (IL-1), interleukin-3 (IL-3), interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and macrophage colony-stimulating factor (M-CSF), was studied in 10 patients and compared with the growth response obtained from unfractionated marrow cells. IL-3 and GM-CSF had a similar stimulating activity on AML-CFU growth. G-CSF resulted the most efficient stimulus for colony formation and was additive or synergistic with IL-3 and GM-CSF, M-CSF, used alone, had a negligible stimulating activity. When CD34+ cells were used, IL-1 by itself had a low stimulating activity and displayed little or no synergy with IL-3, GM-CSF, and G-CSF. On the contrary, when unfractionated cells were used, IL-1 was very effective in inducing AML-CFU formation and was markedly synergistic with IL-3 and GM-CSF. These results show that IL-1-induced leukemic colony formation is prevalently mediated by accessory cells. IL-6 supported AML-CFU growth in seven of 10 cases, thus showing a direct effect on CD34+ leukemic cells, and enhanced the growth of IL-3-(+47 to +167%) and GM-CSF-dependent (+60 to +110%) AML-CFU. Recloning studies of single colonies demonstrated that primary CD34+ AML-CFU, stimulated by IL-3 and GM-CSF, generated secondary and tertiary colonies, whereas primary AML-CFU stimulated by G-CSF and IL-6 failed to give rise to secondary colonies, thus indicating a complete suppression of self-renewal. Sequential recloning of colonies grown in the presence of IL-3 + IL-6 demonstrated that addition of IL-6 and IL-3-containing plates resulted in a nearly complete suppression of self-renewal. In conclusion, these results demonstrate the heterogeneity of the CD34+ leukemic cell fraction and indicate the existence of complex regulatory events at the level of CD34+ leukemic cells. Data obtained from recloning experiments are of therapeutic interest in view of the clinical application of HGFs in the treatment of myeloid leukemias.
Department of Hematology, University of Parma, Italy.
C
C
Carlo-Stella
L
L
Mangoni
C
C
Almici
F
F
Frassoni
W
W
Fiers
V
V
Rizzoli
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D000943:Antigens, Differentiation / Q000032:analysis*; D002455:Cell Division; D002469:Cell Separation; D003115:Colony-Stimulating Factors / Q000494:pharmacology; D004357:Drug Synergism; D005260:Female; D006133:Growth Substances / Q000494:pharmacology*; D006410:Hematopoiesis; D006801:Humans; D007378:Interleukins / Q000494:pharmacology; D015470:Leukemia, Myeloid, Acute / Q000276:immunology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D014411:Neoplastic Stem Cells / Q000276:immunology / Q000473:pathology; D011994:Recombinant Proteins / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000276:immunology / Q000473:pathology
D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D003115:Colony-Stimulating Factors; D006133:Growth Substances; D007378:Interleukins; D011994:Recombinant Proteins