Fibrinogen--proteolysis in acute myelogenous leukemia (AML)

Fibrinopeptides were measured as direct indices of thrombin, plasmin and elastase in plasma samples obtained from patients with AML. Peptide patterns observed were consistent with spontaneous or drug induced plasmin-specific fibrinogenolysis (AML FAB M 1/3), elastase mediated proteolysis (AML FAB M 3/4) or DIC (AML FAB 4/5). DIC was also observed in septic, agranulocytotic patients.     

Structures of O-linked oligosaccharides isolated from normal granulocytes, chronic myelogenous leukemia cells, and acute myelogenous leukemia cells

O-Linked oligosaccharides were isolated from normal granulocytes, chronic myelogenous leukemia cells, and acute myelogenous leukemia cells by alkaline borohydride treatment. Oligosaccharides were fractionated by Sephadex G-50 gel filtration and QAE-Sephadex column chromatography, and their structures were elucidated by fast atom bombardment-mass spectrometry after permethylation and methylation analysis before and after specific exoglycosidase treatments. Results show that normal granulocytes and chronic myelogenous leukemia cells contain a series of O-linked oligosaccharides with the following structure, (formula: see text) where, in normal granulocytes n = 0 is major and n = 1 or 2, and thus polylactosaminyl oligosaccharides are present as minor components. However, these polylactosaminyl oligosaccharides were barely detectable in chronic myelogenous leukemia cells. On the other hand, acute myelogenous leukemia cells, which represent poorly differentiated myeloid cells, mainly contain short O-linked oligosaccharides with 2----6-linked sialic acid as follows. (formula: see text) These results suggest that structures of O-linked oligosaccharides vary in the different maturation stages along the same cell lineage.     

Various uses of BCG and allogeneic acute leukemia cells to treat patients with acute myelogenous leukemia

Summary Ninety-six remission patients with acute myelogenous leukemia have been treated with various forms of immunotherapy and chemotherapy in three distinct studies and the clinical outcome of these patients has been reported. In the first study 22 patients were maintained on chemotherapy alone and 28 patients were given the same chemotherapy and additional immunotherapy consisting of BCG and irradiated allogeneic AML cells given at separate sites weekly. It was found that there was a significant increase in survival time of the patients who received immunotherapy (median 510 days) compared with the chemotherapy alone patients (270 days). The p value for this was 0.03. The reason for this prolongation of survival was mainly due to a markedly increased survival time of immunotherapy patients after they relapsed when compared with the chemotherapy patients (165 days compared with 75 days median, p equal to 0.0005). In the second sequential study 24 patients were given immunotherapy alone consisting of irradiated allogeneic AML cells and BCG given at separate sites, and this was compared with unirradiated allogeneic cells and BCG given to 22 patients. There was no difference in the remission length or survival between these two groups. In the third study 13 patients received irradiated cells and BCG as in Study 1 and a further 11 patients received the same immunotherapy but also received a mixture of cells and BCG given during the first three months. There was no difference in the remission and survival of these two groups. The significance of these results is discussed.     

Sesquiterpenoids from the roots of Inula helenium inhibit acute myelogenous leukemia progenitor cells

One new eudesmane sesquiterpenoid, 11β-hydroxy-13-chloro-eudesm-5-en-12, 8-olide (1), was isolated from the roots of Inula helenium together with nine eudesmanolides (2–10) and one germacranolide (11). Their structures were elucidated on the basis of detailed spectroscopic analyses. All isolates were evaluated for their antiproliferative activities against human leukemia stem-like cell line KG1a. Compound 10 exhibited the most potent effect with the IC₅₀ value of 3.36 ± 0.18 μM. A further investigation revealed that compound 10 could significantly induce apoptosis of KG1a cells. Additionally, compound 10 had an obvious effect on the levels of apoptosis-related proteins (Bcl-2, Bax, cytochrome c, caspase 9 and caspase 3), indicating that the antiproliferative effect of compound 10 on KG1a cells might be mediated through a mitochondria-dependent apoptotic pathway.     

Role of colony-stimulating factors in the biology of acute myelogenous leukemia

A high proportion of acute myeloid leukemias (AML) recently investigated for their capacity to synthesize biologically active bioregulatory molecules was found to accumulate messenger (m) RNA and to produce membrane-bound or -secreted forms of stimulating factors for granulocyte, macrophage and mixed granulocyte-macrophage colony growth. Blast cells have also been found to secrete interleukin 1, tumor necrosis factor-alpha, interleukin 6, and to express receptors for various growth factors as well. However, growth factors like interleukin 2 and interleukin 3 have not been identified as AML products, and several other factors including interleukin 4, interleukin 5, etc. need further evaluation. Responsiveness of clonogenic leukemic cells to exogenous growth-promoting factors in vitro suggests a possible role of these biomolecules in the course of these disorders. Important evidence for the crucial role of growth factors, at least in some subtypes of AML, has been provided by demonstrating constitutive growth factor production by leukemic cells and their autonomous in vitro growth which is dependent on autocrine secretion of a specific growth factor. The concert of mechanisms providing stimulatory and inhibitory signals for hematopoiesis, which is adapted to the various physiological requirements of the organism, may have multiple defects in AML. This leads to successive steps of malfunctioning of cells, which finally express a fully malignant phenotype. In addition, these derangements also lead to defects in accessory cells on the level of mediator communication. However, there is evidence for autonomous growth promotion of AML blast by constitutive production of growth factors active in an autocrine fashion (GM-CSF, G-CSF, interleukin 6) and by recruitment of accessory cells to increase CSF supply (GM-CSF, G-CSF) via molecules such as interleukin 1 and TNF-alpha in a paracrine fashion. Molecular analysis of transformed hematopoietic cells has revealed changes of the genome, e.g., insertion of viral genetic information or cytogenetic fractures at DNA sites controlling growth factor gene activation. These events appear to be crucial in the induction of uncontrolled growth factor expression promoting oncogenic transformation of hematopoietic progenitor cells.     

Evidence for a common leukemia-associated antigen in acute myelogenous leukemia

Summary An antiserum was raised in rabbits to extracts of a pool of acute myelogenous leukemia cells. The immunization protocol used (antibody feedback) gave rise to antisera with marked specificity for AML extracts. After absorption, the antiserum demonstrated essentially no reactivity with cell extracts from 12 individual normal peripheral blood samples, while it reacted positively with 16 individual extracts from AML cells. Reactivity was assayed by the enzyme-linked immunosorbent assay (ELISA). The antiserum was not reactive with extracts from normal PHA-induced blast cells, with extracts of bone marrow cells from six individuals, or with three individual extracts of chronic lymphocytic leukemia (CLL) blast cells. These data indicate that this antiserum is detecting an antigen that is common to AML cells but may not be common to other blast cells.     

Leptotrichia buccalis bacteremia in two patients with acute myelogenous leukemia

Leptotrichia buccalis is rarely implicated in systemic disease. We report two patients with clinically significant L. buccalis bacteremia which developed during the neutropenia secondary to chemotherapy. Based upon our experience, L. buccalis bacteremia should be considered in certain high-risk immunocompromised patients with mucositis and/or gingivitis.     

Similarities in long-term cultures of blood and bone marrow from patients with acute myelogenous leukemia

Dexter-type long-term cultures (LTC) were initiated with peripheral blood (PB) and/or bone marrow cells from 11 patients with acute myelogenous leukemia (AML), and 2 with myelodysplastic syndrome in blastic transformation. Marrow and PB cells from normal subjects served as controls. Assessment of nucleated cells and clonogenic progenitors in the adherent and nonadherent fractions of LTC revealed active hemopoiesis for greater than 5 wks in 4 of 8 cultures of AML blood, and 4 of 7 of AML marrow. The morphology and kinetics of nucleated cells and progenitors with putative normal (granulocyte-macrophage colony-forming units or CFU-gm), and abnormal (blast) phenotype in LTC from AML blood were similar to those from AML marrow, and adherent cells positive for collagen I and III and vimentin were found in both types of LTC. Growth of CFU-gm colonies ceased by wk 5-8 in AML cultures, significantly earlier than in LTC of normal marrow cells (survival of greater than 10 wks), which may indicate derivation of the CFU-gm from a transformed clone or deficiency of stromal function in the leukemic state. In most AML blood and AML marrow LTCs, growth of abnormal (blast) colonies continued until wk 4-6. This study demonstrates certain similarities of morphology and function between LTC of AML blood and AML marrow cells. LTC may provide a useful model for further analysis of circulating primitive hemopoietic progenitor cells in leukemic states.     

Functional characterization of T lymphocytes derived from patients with acute myelogenous leukemia and chemotherapy-induced leukopenia

T-cell–targeting immunotherapy is now considered in acute myelogenous leukemia (AML). Immunotherapy seems most effective for patients with a low AML cell burden, and a possible strategy is therefore to administer immunotherapy early after intensive chemotherapy when patients have a low leukemia cell burden and severe treatment-induced cytopenia. To further investigate this possible therapeutic approach we used a whole blood assay to characterize the proliferative responsiveness (³H-thymidine incorporation) of circulating T cells from AML patients with severe treatment-induced leukopenia, i.e., peripheral blood leukocyte counts <0.5×10⁹/l. This assay will reflect both quantitative and qualitative differences. Responses were compared for 17 AML patients, 6 patients with acute lymphoblastic leukemia (ALL), and a group of 21 healthy controls. Most circulating leukocytes in the AML patients were T lymphocytes, whereas B lymphocytes and monocytes usually constituted <10%. Anti-CD3-stimulated proliferation was significantly lower for AML patients compared with healthy controls. However, proliferation in response to anti-CD3 + anti-CD28 did not differ for AML patients and healthy controls, an observation suggesting that T cells from AML patients have an increased responsiveness in the presence of optimal costimulation that compensates for the quantitative T-cell defect. In contrast, the responses were significantly lower for ALL than for AML patients. We conclude that the remaining T-cell population in AML patients with severe chemotherapy-induced cytopenia show an increased proliferative responsiveness and may represent a therapeutic target when antileukemic immunotherapy is tried in combination with intensive chemotherapy.     

Contribution to the study of periodic chronic myelogenous leukemia

The period (in the order of 40 to 80 days) in periodic chronic myelogenous leukemia (PCML) oscillations is quite long compared with the duration of the cell cycle of the hematopoietic stem cells from which the oscillations are presumed to originate (in the order of one or two days). Our objective is to understand the origin of these long-period oscillations using a G0 model for stem cell dynamics. We determine the local stability conditions and show under what conditions the Hopf bifurcation may occur. We interpret the role of each parameter in the loss of stability, and then examine a simpler model to try to deduce possible changes at the stem-cell level that might be responsible for the characteristics PCML.     

Resonance in periodic chemotherapy: a case study of acute myelogenous leukemia

The effects of periodic chemotherapy administration are evaluated within the context of a G(0)model of the cell cycle. Parameters are estimated for normal bone marrow cells and malignant cells in acute myelogenous leukemia (AML). This model explicitly includes the resting G(0)phase and the feedback mechanism that recruits the cells back into the cell cycle. Periodic chemotherapy administration can induce resonance within our model under high cell kill rate where the average cell cycle times may change during the course of treatment, and therapeutic benefits from these resonances cannot be solely based on cell cycle times in untreated tissue. The depletion rate under chemotherapy and the regrowth rate may differ between the cell populations, and our analysis suggests that this favors the tumour cells. We were able to distinguish between the effects of cycle-non-specific, S -phase-specific and M -phase-specific drugs, and found that these can show differences in sharpness and location of the resonance phenomenon. We conclude that resonance chemotherapy (chronotherapy) is unlikely to be efficacious in the treatment of AML.     

Polymorphism at codon 72 of the p53 gene in human acute myelogenous leukemia.

A common polymorphism at codon 72 of the p53 gene in patients with acute myelogenous leukemia (AML) was analyzed by single-strand conformation polymorphism assay and sodium dodecyl sulfate polyacrylamide-gel electrophoresis of immunoprecipitated 35S-labeled P53 protein. No association between this polymorphism and a marked predisposition to AML was found. The half-lives of these two polymorphic forms of P53 were equivalent in normal phytohemagglutinin-stimulated lymphocytes, while the P53 Pro72 isoform was found to be twice as stable as the Arg72 isoform in Daudi cells.