Seiichi Ohmori

Myelodysplastic syndrome (MDS)-associated inhibitory activity on haemopoietic progenitor cells.

We studied MDS‐associated inhibitory activity, which inhibited colony formation in vitro of granulocyte‐macrophage progenitors (CFU‐GM). Macrophages obtained from MDS bone marrow mononuclear cells (BM‐MNC) when pretreated with granulocyte‐macrophage colony stimulating factor (GM‐CSF) suppressed the growth of normal CFU‐GM. These macrophages were designated as ‘MDS‐derived inhibitory macrophages’. Media conditioned by MDS‐derived inhibitory macrophages (MDS‐CM) also suppressed the growth of normal CFU‐GM. In the MDS‐CM, high levels of prostaglandin E2 (PGE2) and ferritin were found. However, MDS‐CM did not contain detectable levels of tumour necrosis factor (TNF) or gamma‐interferon (γ‐IFN). Antiserum against human placental ferritin and/or against PGE2 blocked the haemopoietic inhibitory activity to some extent.

MDS‐macrophage derived inhibitory activity on myelopoiesis of MDS abnormal clones

Summary. We studied the effect of myelodysplastic syndrome (MDS)‐derived adherent cells on colony formation of granulocyte‐macrophage progenitors (CFU‐GM) in both normal and MDS bone marrow cells. MDS‐adherent cells suppressed the growth of normal CFU‐GM colony formation. Antibodies against ferritin almost totally neutralized the haematopoietic inhibitory activity. Antibody against gamma‐interferon (γ‐IFN) did not have such effect.

Prognostic implication of sequential bone marrow cultures in the myelodysplastic syndromes

Twenty-five patients with newly-diagnosed myelodysplastic syndromes were studied by the clonal culture method at least three times during the clinical course. Clinical outcomes of the patients were classified into: a stable disease (ten patients); subsequent leukemic transformation (eight patients) and nonleukemic death (seven patients). The growth of the marrow granulocyte-macrophage progenitors (CFU-GM) at the time of diagnosis was significantly related to the survival. In addition, sequential changes in the CFU-GM growth patterns correlated with the different clinical outcome of myelodysplastic syndromes patients.

Acquired hypochromic and microcytic sideroblastic anaemia responsive to pyridoxine with low value of free erythrocyte protoporphyrin: a possible subgroup of idiopathic acquired sideroblastic anaemia (IASA)

Patients with idiopathic acquired sideroblastic anaemia (IASA) usually show macrocytic or normocytic anaemia and increased free erythrocyte protoporphyrin (FEP). The mean cell haemoglobin concentration is normal or slightly low. Here we report a pyridoxine‐responsive IASA patient with microcytic and hypochromic anaemia and low FEL level; these features are usually seen in cases of hereditary sideroblastic anaemia. Microcytosis increased during therapy.

Effects of recombinant G‐CSF and GM‐CSF on in vitro differentiation of the blast cells of RAEB and RAEB‐T

To evaluate the effects of recombinant G‐CSF and GM‐CSF on RAEB and RAEB‐T cells, blast cells from 6 patients were incubated in liquid culture systems with these CSFs for 7 days, and their numerical, morphological and functional changes were assessed. Both CSFs stimulated cell growth, but decreased the proportion of blast cells in 5 of the 6 cases. Karyotypic abnormalities persisted during cultivation in some cases. The CSFs also stimualted the expression of part of the esterase activities, and a positive interaction of both CSFs was seen in part. Although CSFs had no significant effects on the ability of cells to reduce NBT or to phagocytize latex particles, the results indicated that they induce partial differentiation of blast cells. It appears that such pathological cells still retain the capacity to respond to growth factors.