The effects of human FLT3 ligand on in vitro human megakaryocytopoiesis

W. Piacibello, L. Garetto, F. Sanavio, A. Severino, L. Fubini, A. Stacchini, G. Dragonetti, M. Aglietta

Research output: Contribution to journalArticlepeer-review


The human homolog of the murine flt3/flk2 gene product is a tyrosine kinase receptor that plays a role in regulating the proliferation and differentiation of cells in the hematopoietic system. Using a plasma-clot clonal assay and a long-term bone marrow culture (LTBMC) system, we studied the effects of the recently cloned human flt3 ligand (FL) alone and in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), or stem cell factor (c-kit ligand [KL]) on human megakaryocytopoiesis. The effects of FL on the primitive megakaryocyte (MK) progenitor cell, the burst-forming unit-megakaryocyte (BFU-MK), and the more differentiated colony-forming unit-megakaryocyte (CFU-MK) were determined. FL alone had no megakaryocytic colony-stimulating activity (MK-CSA), but was capable of augmenting the MK-CSA of both CM-CSF and IL-3. FL synergized with IL-3 at the level of both CFU-MK and BFU-MK and with GM-CSF and KL at the level of CFU-MK. Although FL alone exhibited a limited potential in sustaining long-term megakaryocytopoiesis in vitro, it synergistically augmented the ability of IL-3 and KL, alone or in association, to promote long-term megakaryocytopoiesis. These data indicate that multiple cytokines are necessary to optimally stimulate the proliferation of both classes of MK progenitor cells and that FL plays a significant role in this process by amplifying the MK-CSA of GM-CSF, IL-3, and KL.

Original languageEnglish
Pages (from-to)340-346
Number of pages7
JournalExperimental Hematology
Issue number2
Publication statusPublished - 1996


  • FLT3 ligand
  • in vitro cultures
  • megakaryocytopoiesis

ASJC Scopus subject areas

  • Cancer Research
  • Cell Biology
  • Genetics
  • Hematology
  • Oncology
  • Transplantation


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