Studies on Human Preleukaemia

Classification of patients with myelodysplastic syndromes according to the FAB co-operative group's proposals. Proposals for a redefinition of blast cell type II

53 patients with the myelodysplastic syndromes (MDS) were classified according to the proposals of the FAB cooperative group 1982. 29 patients had refractory anaemia (RA), 10 refractory anaemia with excess of blasts ( RAEB ), 5 RAEB in transformation, 7 RA with ringed sideroblasts and 2 chronic myelomonocytic leukaemia ( CMML ). Counting blast cells type I and II involved no difficulties. 4 of 15 patients who developed acute myeloid leukaemia (AML) according to the FAB classification of 1976 did not fulfill the new 1982 criteria for AML. A redefinition of the blast cell type II to include a more granulated blast cells, without the characteristics of promyelocytes, would solve this problem. We conclude that a redefinition of the blast cell type II might turn out to be useful.

Use of bone-marrow culture in prediction of acute leukaemic transformation in preleukaemia

Bone-marrow granulocyte-macrophage progenitor cell proliferation and regulatory factor (colony-stimulating activity; CSA) production were assessed at presentation and, if possible, subsequently in twenty-one patients with dysmyelopoiesis and less than 5% bone-marrow blasts. Seven patients underwent acute leukaemic transformation 1-35 months after the first marrow culture. Assay of bone-marrow endogenous CSA proved the most useful prognostic test. The rate of transformation in the seven patients with raised CSA at presentation was significantly greater (five transformed and one died at or before 4 months) than that in the fourteen patients with normal, low, or undetectable CSA (two transformed at 27 and 35 months). In one of the latter an increase in bone-marrow CSA occurred 6 weeks before transformation (serial marrow samples were not available in the other case). No other marrow culture feature measured, including the presence or absence of granulocyte-macrophage colony-forming cells and total clone numbers (colonies and smaller clusters) was as useful.

Erythroblast iron metabolism in sideroblastic marrows

The uptake of iron by bone marrow erythroblasts and its intracellular distribution have been studied in 23 patients with primary sideroblastic anaemia (SA), five patients with secondary SA and one patient with only non-ringed sideroblasts. EM of erythroblasts from 18 cases showed both mitochondrial iron deposits and cytoplasmic ferritin aggregates in all cases except the patient with only non-ringed sideroblasts. Iron uptake by erythroblasts in whole bone marrow was normal but there was a decreased incorporation into haem and an increased incorporation into cell stroma. Age matching of erythroblasts using Percoll density gradient centrifugation indicated that stromal iron incorporation was high at all stages of erythroblast development even before haem synthesis had become a major metabolic activity and in intermediate and late erythroblasts a real decrease in haem synthesis appeared less certain. These observations, together with the inability to correct the abnormality in vitro with either pyridoxal phosphate or delta amino-laevulinic acid suggest that the primary defect in SA may be an abnormality of mitochondrial iron metabolism rather than an abnormality of haem synthesis.

The applicability of simple blood and bone marrow variables in prediction of acute leukaemia in patients with acquired bi- or pancytopenia

A retrospective study of 44 patients presenting with acquired bi- or pancytopenia (B/PC) and no evidence of any causal disorder was carried out. 12 patients developed acute non-lymphoblastic leukaemia after 2-51 months. Compared to the nonleukaemic subjects the preleukaemic patients at the onset of B/PC had significantly higher counts of myeloblasts and other myelopoietic cells in the bone marrow, more cellular marrows due to more dense cellularities of all compartments, higher blood granulocyte and monocyte counts, more pronounced anisocytosis, and in some cases a small number of circulating myeloblasts. A stepwise multiple logistic regression analysis identified 3 combinations of variables displaying significant simultaneous association with subsequent leukaemic transformation. Among these the combination of marrow myeloblast percentage and blood granulocyte count might be applicable to early prospective identification of patients with preleukaemic B/PC.

The preleukemic syndromes (hematopoietic dysplasia) in childhood

The preleukemic syndrome or hematopoietic dysplasia is a marrow stem-cell disorder with clinically recognizable hematologic abnormalities which precede the development of acute nonlymphocytic leukemia. Its occurrence in childhood is extremely rare; seven "true" cases who fulfill all the criteria for the disorder have been reported until now. The preleukemic syndrome is generally characterized by peripheral cytopenia with fairly specific morphologic abnormalities in cell differentiation. The hematological and clinical features permit recognition of preleukemia even before the development of overt leukemia. Experimental data indicate that preleukemia is an "early" leukemic syndrome in which hematopoietic cell differentiation becomes progressively impaired with termination in the nearly complete maturation block which is characteristic of acute myelogenous leukemia.