Growth analysis of marrow CD34-positive hematopoietic progenitor cells in patients with myelodysplastic syndromes.

The in vitro colony-forming capacities of marrow CD34-positive (CD34+) cells from 25 patients with myelodysplastic syndromes (MDS) were studied. In all patients this purified cell population showed erythroid (burst-forming unit erythroid; BFU-E) or non-erythroid colony growth, both of which were more restricted than non-purified mononuclear cell population under stimulation with erythropoietin (EPO) or granulocyte/macrophage colony-stimulating factor (GM-CSF) alone. MDS patients examined were put into two groups; refractory anemia (RA) or RA with ringed sideroblasts (RA/RARS) and RA with excess of blasts (RAEB) or RAEB in transformation (RAEB/RAEB-t). The CD34+ cells of both RA/RARS and RAEB/RAEB-t exhibited a similarity to the cells of normal individuals in their responsiveness to the addition of interleukin 6 (IL-6), IL-3 or stem cell factor (SCF). SCF caused powerful but highly variable responses in both erythroid and nonerythroid colony formation as compared with IL-6 or IL-3. We demonstrated that MDS marrow hematopoietic progenitor cells reactive to GM-CSF or EPO were additionally stimulated with early-acting hematopoietic growth factors including IL-6, IL-3 and SCF in a fashion similar to those of normal individuals.