Human preleukaemia cell culture studies in sideroblastic anaemia

Effect of 5637-conditioned medium on peripheral blood granulocyte-macrophage progenitors in normal subjects and patients with the myelodysplastic syndrome

There was no overall increase in PB-CFU-GM from normal subjects, or MDS patients, when exogenous CSA (5637-CM) was added to the culture medium. However, there was a sub-group of MDS patients (seven of 35) whose PB-CFU-GM numbers were significantly stimulated by 5637-CM. In addition, there were 11 (out of 48) MDS patients with undetectable PB-CFU-GM in assays without exogenous CSA but only two when 5637-CM was added (p less than 0.01). This sub-group is of particular interest as it is known that those without detectable PB-CFU-GM tend to have significantly shorter survival times than others. The mechanism of the functional abnormality is yet to be determined.

Predictive value of bone marrow cultures in 48 patients with acute myeloblastic leukaemia or myelodysplasia both secondary to treatment of other malignant diseases

The growth pattern of bone marrow cells in agar cultures was studied in 48 patients with acute myeloblastic leukaemia or myelodysplasia, secondary to cytoreductive treatment, and compared to other laboratory findings. At diagnosis the status of the patients was: acute myeloblastic leukaemia (AML) in 9, acute myeloproliferative syndrome (AMS) in 13 and preleukaemic syndrome (PL) in 26 patients. 20 of the 39 patients with AMS and PL developed acute leukaemia, 15 of them within 1 year. 15 died of complications to cytopenia and only 4 are still alive and without leukaemia, observed from 8 to 55 months. Progression to AML was predicted from the agar cultures by increased cluster growth. Among 18 patients with increased cluster growth at diagnosis 14 subsequently developed AML. Among 21 patients with normal or decreased cluster growth at diagnosis 6 patients developed AML, but after conversion of the growth pattern to increased cluster growth. In 2 patients the increased cluster growth disappeared spontaneously and the patients are long-term leukaemia-free survivors. Colony growth pattern, conversely, was not related to leukaemic progression. Only 1 patient had normal growth pattern at diagnosis with respect to both clusters and colonies. Survival was short, with a median of about 7 months, unrelated to growth pattern and leukaemic progression.

Colony assays of hematopoietic progenitor cells and correlations to clinical situations

The production of blood cells is a dynamic process that is noticeably aberrant during disease. The availability of colony assays in vitro that allow detection of hematopoietic stem and progenitor cells for the neutrophil, monocyte-macrophage, erythroid and/or megakaryocyte lineages has been of importance for the present understanding of the mechanisms controlling the proliferation, self-renewal capacity, and differentiation of morphologically nonrecognizable immature cells which give rise to the mature progeny circulating in the blood. It is through the use of these assays that the existence of potentially relevant stimulatory and inhibitory feedback interactions has been demonstrated. Abnormalities in these interactions, which may be of significance during leukemia and related disorders, have been uncovered. This communication will discuss regulatory interactions detected via the colony assays, their potential relevance physiologically and pathologically, and the use of these assays for diagnosis, prognosis, and for monitoring the clinical status of patients.

In vitro colony and cluster growth in haemopoietic dysplasia (the preleukaemic syndrome). II. Identification of a maturation defect in agar cultures

The growth and differentiation of granulopoietic progenitor cells from 15 patients with haemopoietic dysplasia were studied by in vitro culture in agar-gel. After 14 d in culture whole colonies and clusters were transferred to glass slides and were stained with a modified Papanicolaou technique. The preparations were examined for cellular differentiation by counting the number of mature cells (band forms and polymorphonuclear cells) and a mitotic index was calculated from the number of mitotic cells. Patients with defective colony formation showed granulopoietic maturation defects and a reduced mitotic index was found in some colonies. Patients who had colony counts within the normal range, however, showed normal in vitro maturation. Defective colony growth in haemopoietic dysplasia generally indicates a malignant course and can occasionally be related to leukaemic transformation. The finding of in vitro maturation defects in an additional culture abnormality which may indicate a deteriorating clinical course. A defective maturation and a reduced mitotic index in vitro add support to the concept of clonal progression in malignant haemopoietic dysplasia.

Levamisole: evidence for activity on human haemopoietic progenitor cells

Levamisole, which has immunostimulant activity, is now being used to treat some forms of cancer. We report that the drug enhances granulocyte colony formation. The mechanism of action appears to be partly through modulation of molecules on cell membranes. The molecular content of colony-stimulating activity (CSA) released into leucocyte-conditioned medium by cells of leukaemic and some preleukaemic patients can be quantitatively altered by levamisole, both in vitro and in vivo, but the CSA produced is qualitatively similar to that released by normal cells. The demonstrated levamisole enhancement of colony formation, and altered CSA types detected in leucocyte-conditioned medium, makes this drug a promising candidate for treatment of selected leukaemic states and in preleukaemia.

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.

Erythroleukemia following drug induced hypoplastic anemia

Three patients with drug-induced hypoplastic anemia terminating 2 to 6 years after presentation with erythroleukemia are described. All were treated for prolonged periods with androgen and corticosteroid and two of the patients showed apparent dependence on this therapy for optimal hematologic status. The leukemic phase was heralded by loss of this dependence and development of sideroblastic dyserythropoiesis with progression to bizarre erythroid hyperplasia and fatal cytopenia. The exact relationship between androgen and corticosteroid therapy and the erythroleukemia remains speculative.

Idiopathic refractory sideroblastic anemia: incidence and risk factors for leukemic transformation

The clinical course of 29 patients with idiopathic refractory sideroblastic anemia studied by us was reviewed. Four patients developed acute leukemia. We were able to find 27 out of 268 cases of idiopathic refractory sideroblastic anemia reported in the literature which terminated in acute leukemia. Nine of these were well described. The overall incidence of acute leukemia is 10%. In an attempt to identify the risk factors for the development of acute leukemia, the clinical and laboratory features of this group of thirteen well-described cases which terminated in acute leukemia were compared to the remaining 25 of our cases which did not undergo leukemic transformation. The patients who died of acute leukemia tended to have a more severe anemia, a lower reticulocyte count, and increased transfusion requirement, and thrombocytopenia. Thrombocytosis appears to be a relatively good prognostic sign.

Normal and leukemic hemopoiesis compared

Using colony assays for human erythropoietic (BFU-E, CFU-E) and granulopoietic (CFU-C) progenitors, normal and leukemic myelopoietic differentiation were compared; similar patterns were found in both. However, the origin of blast cells characteristic of the disease could not be established indicating the need for a direct approach to these cells. A colony assay for blast cells in acute myeloblastic leukemia is described. Blast cell colony-formation is significantly correlated with blast cell number, and the colonies contain cells of blast like morphology without differentiation markers. It is proposed that this method, taken in conjunction with results from assays of myelopoiesis and lymphopoiesis, may provide a more complete picture of leukemic differentiation. It is anticipated that such a model will be useful in devising new therapies.

The preleukemic syndrome (hemopoietic dysplasia)

Retrospective analysis of patients with acute myelomonoblastic (or nonlymphocytic) leukemia has helped to clarify the early stages of the evolution of this disease, and a clinical picture has emerged that is sufficiently discriminating to permit prospective observations. The clinical and laboratory features of the hematologic disorder preceding overt, blast-cell leukemia (i.e., the "preleukemic syndrome" or "hemopoietic dysplasia") are described, and diagnostic criteria and approaches to management are considered. This hematologic syndrome appears to be a stage in a multiphasic panmyelopathy that involves all products of the marrow stem cell. Available data indicate that most of these patients develop acute leukemia within 24 months of the onset of the hematologic abnormalities, but longer courses are not uncommon. Prospective documentation in a large group of patients is needed before the natural course can be accurately defined; such studies are now being planned.

Differentiation in human myeloblastic leukemia studied in cell culture

Normal adult hemopoiesis orginates in pluripotent stem cells; among the early differentiated descendents of such cells are progenitors committed to the erythropoietic, granulopoietic, or megakaryocytic pathways of myeloid differentiation. These may be detected in cell culture by developmental techniques, in which progenitors form colonies in viscid or semisolid media in response to appropriate stimulation. Certain diseases of hemopoiesis also originate in pluripotent stem cells; these include chronic myeloblastic leukemia, acute myeloblastic leukemia, polycythemia vera, and idiopathic myelofibrosis-the clonal hemopathies. The hypothesis is advanced that the distribution of cell classes among patients with clonal hemopathies is determined both by the differentiation potential of each pluripotent stem cell maintaining an abnormal clone and by random events occurring during clonal expansion. The latter process may account for the large variations observed between patients when committed progenitors are assayed in cultures of marrow from patients with acute myeloblastic leukemia (AML). This variation may also be used to estimate lineage relationships in the clonal hemopathies. When applied to myelopoiesis in AML, obvious differences from the normal are not detected. The analysis is consistent with the view that the blast cell population in AML is distinct from the leukemic myelopoiesis occurring within an abnormal clone. A new assay procedure is described for progenitor cells related to blast cell proliferation. Finally, these concepts are used to develop a model for the pathogenesis and cellular characteristics of AML.

Cell culture studies in 19 cases of refractory aneamia: comparison of clinical data with in vivo erythrokinetic studies

A total of 19 cases of chronic refractory anaemia underwent simultaneous in vivo erythrokinetic study and in vitro bone marrow culture. They were followed up clinically for at least 2 years. Good correlation has been found between erythrokinetic data (simultaneous quantitative and qualitative disorders of erythroblastic proliferation in preleukaemic states; pure qualitative disorders in primary sideroblastic anaemia) and the results of culture of granulocyte precursors in the bone marrow (small number of colonies, reduced size of colonies in preleukaemic states; normal number and growth in non malignant refractory anaemia). It would seem thus that both examinations are of practical interest in clinical haematology, making it possible to foresee the malignant evolution of some refractory anaemias.