Megakaryocyte colony formation by bone marrow progenitors in myelodysplasia syndromes

Summary. Megakaryocytic colony formation by precursor cells from the bone marrow was investigated in 10 patients with a myelodysplastic syndrome. All but one exhibited abnormal colony formation: four showed no colony formation at all, while a decreased number of colonies was noticed in five. All of the patients showed defective colony formation by erythroid progenitors, but only four showed clearly abnormal granulocyte‐macrophage colony formation. The defect in megakaryocytic progenitors seems to be more akin to the defects occurring in erythroid progenitors than to the defects seen in the granulocyte‐macrophage lineage.