EFFECTS OF GRANULOCYTE-COLONY-STIMULATING FACTOR THERAPY ON IN-VITRO HEMATOPOIESIS IN MYELODYSPLASTIC SYNDROMES

We evaluated the effects of 2 months of G-CSF treatment on in vitro he matopoiesis in 17 patients with myelodysplastic syndromes (MDS). Altho ugh in vitro marrow myeloid progenitor cell (CFU-GM) growth stimulated by G-CSF generally remained subnormal, in the majority of neutrophil responders significantly augmented incremental change (termed AIC) of CFU-GM numbers occurred after treatment, as did neutrophilic different iation. The neutrophil non-responders had less prominent in vitro myel oid responses and lower basal neutrophil levels (p < 0.05). Following G-CSF treatment, the initially subnormal erythroid burst-forming unit (BFU-E) values underwent AIC in five of 11 patients along with increas ed reticulocyte responses in vivo, whereas four of the five patients w ho lacked AIC of BFU-E did not. Three patients with persisting cytogen etic abnormalities and increased neutrophilic differentiation in vitro also responded in vivo, suggesting that G-CSF induced in vivo cellula r differentiation from the abnormal clone. Two of the three patients w ho developed blastic responses in vivo had increased CFU-GM growth pre - and post-therapy. These results indicate in vivo-in vitro correlatio ns for myeloid and erythroid responses of MDS marrow cells which relat ed to treatment with G-CSF.