Marked and reproducible increase in trilineage blood cell counts by administration of granulocyte colony-stimulating factor in a patient with refractory anaemia with excess blasts in transformation.

We report a patient with refractory anaemia with excess blasts in transformation (RAEB-t) who presented with severe pancytopenia and received four intermittent series of granulocyte colony-stimulating factor (G-CSF) treatment over 1.5 years. In addition to the increase in mature neutrophils, platelet count and haemoglobin level were dramatically increased. These haematological improvements were dependent on G-CSF during these treatment series. Bone marrow colony assay revealed that G-CSF increased both CFU-E- and BFU-E-derived colonies in vitro. Clinical usage of G-CSF in myelodysplastic syndrome (MDS) is discussed, with particular emphasis on mechanisms of trilineage response.