Erythroid and granulocyte-macrophage colony formation in myelodysplastic syndromes.

Colony formation by haematopoietic progenitors from the bone marrow was studied in 44 patients with a myelodysplastic syndrome. Erythroid progenitors BFU-E and CFU-E were cultured in methyl cellulose, and granulocyte-macrophage precursors CFU-GM in agar. 3 of 32 patients showed normal numbers of BFU-E colonies; in all the other cases the number of these colonies was below the normal range. CFU-E colony formation was subnormal in all cases. 23 of 44 patients grew normal numbers of colonies and clusters in CFU-GM cultures. These patients had refractory anaemia with ring sideroblasts (FAB-classification) or 5q-karyotype anomaly in the marrow. Patients lacking both of these findings exhibited reduced colony formation or excessive growth of colonies and/or clusters, with few exceptions. In conclusion, we found that erythroid colony formation was defective in all cases. Normal granulocyte-macrophage colony formation was associated with refractory anaemia with ring sideroblasts or the presence of 5q- karyotype anomaly.