Detection of minimal residual disease in acute myeloid leukemia.

The distinction of clonogenic leukemic cells (CFU-L) and normal myeloid progenitors (GM-CFU) is a problem because both types of cells respond to the same growth factors and their clones resemble each other morphologically in culture. We investigated by means of an indirect enzyme-immunoassay the expression of "early" and "late" differentiation markers on bone marrow cell suspensions, as well as on agar clones in 18 cases of newly diagnosed acute myeloid leukemia (AML) as compared with 13 normal controls. Uncultured AML cells carried only low amounts of "late" myeloid differentiation antigen (CD15) but expressed nearly normal levels when cultured in agar with colony-stimulating factor (CSF). In contrast to normal bone marrow, AML cells were strongly reactive with "early" differentiation markers (CD10, CD20, CD34) and remained so during culture. Normal and leukemic agar clones could be specifically distinguished by CD20- and CD34 antibodies. By means of a double marker technique, it could be shown that "late" myeloid differentiation markers (CD15) and "early" markers (CD10, CD20, CD34) were coexpressed on the same cells only in AML but not in normal bone marrow. Leukemic clones were identified by phenotyping of agar clones in 17 of 19 cases investigated during complete clinical remission (CR) of the disease. A formal proof of the leukemic origin of CD20/CD34 positive clones grown in CR was made possible in four cases either by Southern blot analysis or by a cytogenetic marker. These results demonstrate that AML cells can partially differentiate in vitro in the presence of CSF. A distinction of AML from normal clones, however, is possible by their reactivity with "early" differentiation markers, because this is maintained under the differentiating influence of CSF. The technique described here identifies residual leukemic clones in the majority of AML in CR, which persist at a constant rate and increase 6 months before cytological relapse.     

Allogeneic transplantation of blood stem cells concentrated by density gradients

Discontinuous albumin density gradients were used to physically separate hemopoietic cells from immunocompetent lymphocytes in peripheral blood mononuclear cells of dogs. Transplantation of these stem cell concentrates into lethally irradiated allogeneic recipients restored hemopoiesis in nine of 12 animals. Tolerance and long-term survival, however, were achieved only in pairs matched for major histocompatibility antigens. These animals showed stable chimerism in bone marrow cells but transiently regenerated autochthonous cells demonstrable only in the peripheral blood. As compared with earlier studies using grafts of unseparated peripheral blood mononuclear cells, the numbers of CFUc transplanted were similar; the number of mononuclear cells, however, was reduced by a factor of 60. It thus appears that the granulocyte-macrophage colony-forming assay (GM-CFUc) is able to predict within limits the hemopoietic potential of a graft. Although very low numbers of blood-derived CFUc were effective (33,000-42,000/kg body weight), the superiority of blood stem cells over bone marrow grafts remains to be established.     

Ferritin in bone marrow and serum in iron deficiency and iron overload

Summary Nonheme iron and ferritin in the bone marrow and serum ferritin was investigated in patients with iron deficiency anaemia or iron overload. As controls served patients without any disturbance of the iron metabolism.There is a precise correlation between the nonheme iron and ferritin in the bone marrow of patients with and without disturbance of iron metabolism. A correlation was also found between the ferritin in the bone marrow and the serum. Nonheme iron and ferritin in the bone marrow and serum ferritin was decreased in patients with iron deficiency anaemia. Conversely, the same parameters were increased in patients with iron overload.     

Cytokines can reduce clonal, CD34-positive cells in acute myeloid leukemia in vitro

We studied the influence of cytokine mixes on the survival of acute myeloid leukemia (AML) bone-marrow (BM) cells in a 14-day culture assay in vitro. Southern-blot analysis using a panel of different probes in combination with densitometry and flow cytometry were used to detect and compare the amount of clonal or CD34-positive BM cells before and after the culturing procedure. A significant reduction of CD34-positive cells after incubation with a cytokine mix [interleukin (IL)-1β, IL-3, IL-6, stem cell factor (SCF), erythropoietin (EP) with granulocyte macrophage/colony-stimulating factor (GM-CSF, Cytok1] could be achieved in all 16 cases with a CD34-positive blast phenotype studied at diagnosis (P<0.001), in 3 of 10 cases at relapse, and in 8 of 18 cases in complete remission. In healthy donors, an increase of CD34-positive cells was demonstrated in 5 of 5 samples. A reduction of clonal DNA through incubation with Cytok1 was achieved in 5 of 5 (100 %) cases studied at diagnosis, in 1 of 4 (25%) cases at relapse, and in 7 of 9 cases (78%) in complete remission. Cytokine cocktails with GM-CSF (Cytok1) were more efficient in reducing (clonal) CD34-positive cells than cocktails without GM-CSF (Cytok2). AML patients at diagnosis and in complete remission had a better survival probability if their CD34-positive or clonal cells could be reduced in vitro by cytokine cultivation (P<0.05). Vitality of BM cells was not influenced by 14-day cytokine treatment; however, the total cell count could be increased by Cytok1 and Cytok2 by 55–174%, but not by the control medium. Our data show that: (1) clonal cell populations can be regularly detected at diagnosis, during complete remission, and at relapse; (2) CD34-positive cells in AML can be demonstrated to be clonal, gene-rearranged cells; (3) incubation of AML BM-cells with Cytok1 leads to a reduction of the CD34-positive, clonal cell load in all cases at diagnosis and in 78% of the cases in complete remission of AML, but in only 25% of the cases at relapse; (4) in all healthy BM samples, proportions of ‘healthy’ CD34-positive cells were increased. Moreover, absolute cell counts were increased by cytokine incubation of cells obtained at diagnosis, relapse, or complete remission of AML and from healthy donors indicating a selective stimulation of healthy, but not of leukemic CD34-positive cells; (5) cytokine cocktails containing GM-CSF are more efficient in reducing leukemic cells than cocktails without GM-CSF; and (6) in vitro reactivity of clonal or CD34-positive BM cells against Cytok1 has clinical relevance. We conclude, that Southern-blot analysis and flow cytometry are suitable methods to detect and quantify leukemic disease and to distinguish between clonal or non-clonal CD34-positive cells. The ex vivo or clinical application of specific combinations of cytokines might be a feasible and successful application of immunotherapy in AML that merits further investigations. Received: 19 April 1999 / Accepted: 13 January 2000     

Enhanced endogenous leukotriene biosynthesis in patients treated with granulocyte-macrophage colony-stimulating factor

The hematopoietic cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) is being used in clinical trials for its potential in the treatment of hematopoietic insufficiency due to various causes. Involvement of leukotrienes in the effects of GM-CSF is suggested by analytical and pharmacologic evidence obtained in vitro. However, until now no data in support of a role of leukotrienes in GM-CSF action in vivo have been presented. In the present investigation this question was approached by measurement of endogenous cysteinyl leukotriene formation in patients treated with the cytokine for cytopenia induced by cytostatic drugs or for refractory anemia with excess of blasts (RAEB). Endogenous cysteinyl leukotriene formation was assessed by determination of urinary leukotriene metabolites using combined high-performance liquid chromatography and radioimmunoassay analysis. After GM-CSF administration a distinct increase in urinary cysteinyl leukotrienes was found in the cytopenic and the RAEB patients that ranged from 2.3- to 57-fold and 2.4- to 333-fold, respectively. In the cytopenic patients the increase in leukotriene production was correlated to an expansion of peripheral blood leukocytes; RAEB patients responded to GM-CSF with enhanced leukotriene biosynthesis even if the peripheral leukocytes decreased, possibly due to an abnormal number and/or irritability of leukotriene-producing cells. The increase in endogenous leukotriene production during therapy with GM-CSF may indicate that leukotrienes play a role in GM-CSF action in vivo.     

Sind die serologischen Tuberkuloseproben spezifisch?

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Über die Temperatur der Exspirationsluft und der Lungenluft

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