Effect of culture conditions on in vitro erythroid colony formation in myelodysplastic syndromes.

In vitro colony formation by erythroid progenitors from the bone marrow was studied in 42 patients with a myelodysplastic syndrome using both a standard assay for growing erythroid colonies and an assay designed for growing megakaryocyte colonies. In the standard assay 5 patients had normal numbers of erythroid burst-forming unit (BFU-E) colonies, 8 showed reduced numbers of colonies, and 29 patients had no colony formation. Six patients with markedly reduced numbers of erythroid colonies or no colonies at all in the standard assay showed normal or increased numbers of erythroid colonies in the megakaryocyte assay. In three of these patients the erythroid colony morphology was normal, whereas the other three showed abundant diffuse growth of erythroid subclusters with no normal colonies. In the other patients, the erythroid culture results were similar in both assays. These results indicate that the impairment of erythroid colony growth seen in most patients with a myelodysplastic syndrome is, at least in a number of patients, not due to reduced numbers of erythroid progenitors but to unusual milieu requirements of abnormal progenitors.