Purpose: The expansion of an abnormal hemopoietic stem cell line is responsible for the myelodysplastic syndromes, which are characterized by pancytopenias, often resulting in lethal infections. Cloned granulocyte colony-stimulating factor (G-CSF) was recently shown to enhance the growth and differentiation of normal granulocyte progenitor cells in vitro. The aim of our study was to examine the effects of recombinant human G-CSF in patients with myelodysplastic syndromes.
Patients and methods: Four patients with myelodysplastic syndromes and one patient with smoldering acute myelogenous leukemia following the occurrence of a myelodysplastic syndrome received recombinant human G-CSF by intravenous infusion for six days. Patients received different dosage levels (50 to 1,600 micrograms/m2).
Results: A response was seen in all patients, with an increase in both immature myeloid cells in the bone marrow and mature granulocytes in the peripheral blood. The dose levels that could stimulate granulocytopoiesis differed among patients.
Conclusion: These results suggest that, at least in some cases of myelodysplastic syndromes, granulocytopenia can be improved by G-CSF, although it still remains to be determined whether the increase in the number of granulocytes is due to the differentiation and maturation of the myelodysplastic clone or restoration of a residual normal clone.