Biomedical subjects

K Spiekermann

Publications and source records attributed to K Spiekermann.

15 recordsLinked to original sources

PubMed2006

[Risk-adapted therapy of acute myeloid leukemia].

Antineoplastic Agents↗

PubMed2005

Towards a pathogenesis-oriented therapy of acute myeloid leukemia.

Genetic and molecular techniques have provided increasing insights into the biology of acute myeloid leukemia (AML). These investigations showed that AML is not a homogeneous disease but a heterogeneous group of biologically different subentities. These subentities are currently primarily defined by cytogenetics by which three main subgroups can be discriminated: AML with balanced translocations, AML with unbalanced aberrations and AML without cytogenetically detectable aberrations. Within the latter group molecular alterations are identified in more than half of cases such as NPM mutations, FLT3 mutations, MLL duplications and mutations of CEBP-alpha. The clinical meaning of these findings is illustrated by substantial differences in response to therapy and long-term outcome. As demonstrated by the recent multicenter trial of the German AML Cooperative Group (AMLCG) and other studies intensification of induction therapy may improve the results in distinct subtypes but fails to do so in others. Therefore, new strategies need to be explored which incorporate the knowledge about the biology of AML to develop biology adapted treatment strategies. This process has just begun and is predominantly determined by the availability of new agents and their evaluation in clinical phase I and II studies. A variety of targets are currently explored and some trials have yielded promising results already. The step towards a biology adapted treatment of AML is long and requires the combined efforts of researchers, clinicians and the pharmaceutical industry. The first steps towards this goal have been taken and give rise to the hope for more effective and more specific therapies of AML.

Combined Modality Therapy↗

PubMed2005

[Mutations of the gene coding for the receptor tyrosine kinase FLT3 in acute myeloid leukemia. Significance as the disease-specific molecular marker for diagnosis, prognosis and innovative therapy approaches].

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Biomarkers, Tumor↗

PubMed2005

[Molecular target structures in oncology].

Substantial progress has been made in recent years in understanding the molecular pathogenesis of malignant disorders, especially in identification of molecular targets for therapeutic interventions ("targeted therapies"). An important group of therapeutical targets are signaling cascades, e.g. protein tyrosine kinases (PTK) that are activated by mutations, translocations or overexpression. Small molecule inhibitors that compete with ATP and inhibit kinase activity have produced clinical impressive responses in chronic myeloid leukemia, gastrointestinal stroma tumors and non-small cell lung cancer. Another group of cellular targets is represented by tumor-selective cell surface proteins that can serve as target structures for antibodies. Therapeutical concepts using monoclonal antibodies have substantially improved response rates in patients with malignant lymphomas and are currently evaluated in other types of cancer. The definition of molecular target structures critical for the malignant phenotype is driving a new era of integrated diagnostics and therapeutics in the field of oncology.

Animals↗

PubMed2001

Constitutive activation of STAT transcription factors in acute myelogenous leukemia.

Hematopoietic growth factors (HGF) are essential for proliferation and differentiation of hematopoietic precursors and activate a distinct set of JAK-STAT (Janus kinases-signal transducers and activators of transcription) proteins. Previous results from our group have shown a strong expression of JAK-STAT proteins in primary acute myelogenous leukemia (AML) blasts and AML cell lines. Here, we asked whether a constitutive activation of the JAK-STAT pathway might be involved in the pathogenesis of AML. We could demonstrate a constitutive activation of STAT1, 3 and 5 by immunoprecipitation of the tyrosine phosphorylated proteins in different human AML cell lines. Three patterns of STAT activation were found: (I) activation of only STAT1, (II) activation of STAT1 in combination with STAT3, and (III) activation of STAT1, 3 and 5. Furthermore, STAT1 and 3 formed stable heterodimers only in cell lines with constitutive STAT3 activation. In all cell lines analyzed, tyrosine phosphorylation of the four known Janus kinases could not be detected, although JAK1 was stably associated with STAT3. To further analyze whether a constitutive activation of tyrosine kinases might contribute to the autonomous growth of AML blasts, inhibitor studies were performed. The tyrphostin AG490, an inhibitor of the JAK-STAT pathway, but not A1, an inactive tyrphostin induced a time- and dose-dependent growth arrest without overt morphological signs of differentiation in AML cell lines. Our results show that STAT transcription factors are constitutively activated in human AML cell lines and might contribute to the autonomous proliferation of AML blasts. Inhibition of this pathway might be of interest for the establishment of more specific antileukemic strategies.

Acute Disease↗

PubMed1999

Expression of granulocyte colony-stimulating factor- and granulocyte-macrophage colony-stimulating factor-associated signal transduction proteins of the JAK/STAT pathway in normal granulopoiesis and in blast cells of acute myelogenous leukemia.

Acute myelogenous leukemia (AML) is characterized by the malignant transformation of hematopoietic stem cells leading to dysregulated growth and differentiation of myeloid cells. Normally, proliferation and differentiation of myeloid cells are regulated by cytokines such as granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF). Abnormal signaling of the signal transduction pathway from the cytokine receptors via Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) might be involved in the pathogenesis of AML. We examined whether an abnormal expression of one of the four JAKs, STAT1, STAT3, STAT5, or the tyrosine phosphatase SHP-1, a negative regulator of this pathway, is associated with malignant transformation in AML. Analysis of the expression of proteins of the JAK/STAT pathway in normal myeloid cells at three stages of maturation revealed a strong expression of all proteins in CD34+ cells, whereas the level of the proteins was significantly lower in granulocytic precursors and mature neutrophils. Furthermore, during maturation the relation of the isoforms of STAT1 and STAT3 changed from predominantly alpha to predominantly beta. Leukemic blast cells from 25 patients and 12 cell lines showed a high level of STAT proteins and SHP-1, whereas a deficiency of at least one of the four JAKs was found in 10 of 25 patients. In primary AML blast cells a deficiency of three JAKs was more common in patients with an abnormal karyotype. In addition, a lack of JAK2 and Tyk2 protein was strongly associated with the FAB M2 phenotype. The proliferation rate in response to GM-CSF available in a small number of patients appears to be related to the JAK2 expression. Our data suggest that the degree of expression of G-CSF/GM-CSF receptor-associated proteins of the JAK/STAT pathway in normal myeloid cells is related with their clonogenic potential. STAT3 appears to be involved in early differentiation. Similar to CD34+ cells, it is likely that the high levels of STATs and SHP-1 found in leukemic cells reflects their proliferative activity, whereas a lack of members of the JAK family might lead to an inability to proliferate in response to G-CSF/GM-CSF described in a considerable percentage of AML blasts.

Antigens, CD34↗

PubMed1997

Functional features of neutrophils induced by G-CSF and GM-CSF treatment: differential effects and clinical implications.

G-CSF and GM-CSF are hematopoietic growth factors required for proliferation and differentiation of hematopoietic precursors. G-CSF is now widely used to overcome neutropenias of various origins. Beside the absolute number, the functional capacity of neutrophils at sites of inflammation is of major importance in host defense. This review summarizes major functional and phenotypical features of neutrophils induced by G-CSF treatment in patients with acquired and congenital neutropenias. Furthermore, we focus on the differential effect of G-CSF and GM-CSF on neutrophil function in vitro and in vivo. Some of the altered abilities of cytokine-induced neutrophils are important to understand side-effects of G-CSF therapy.

Cell Adhesion↗

PubMed1997

Combination chemotherapy with CHOP for recurrent thrombotic thrombocytopenic purpura.

We report the case of a 42-year-old woman with chronic recurrent thrombotic thrombocytopenic purpura. Therapy with corticosteroids, high-dose immunoglobulins, plasma exchange and cyclophosphamide only induced short-lasting remissions during a course of almost 3 months. Following a severe relapse on day 90 after the start of symptoms, polychemotherapy with cyclophosphamide. adriamycin, vincristine and prednisolone (CHOP) was begun. After two cycles of CHOP the patient has stayed in complete remission, with normal platelet counts for more than 9 months to date.

Adult↗

PubMed1996

Surface and mRNA expression of the CD52 antigen by human eosinophils but not by neutrophils.

Eosinophilic and neutrophilic granulocytes represent major effector cells in the inflammatory response. Whereas neutrophils are predominantly involved in bacterial infections, eosinophils are of essential importance in the allergic inflammation. Surface markers have been used to distinguish neutrophils (CD16+) from eosinophils (CD16-) and might indicate different functional properties of these cells. In this study, expression and functional activity of CD52 on human eosinophils and neutrophils was investigated in nonatopic healthy donors and from patients with hypereosinophilia. Flow cytometric analysis using different anti-CD52 monoclonal antibodies (MoAbs) (mouse IgG3, humanized IgG1, and rat IgM) showed significant and homogeneous expression of CD52 on human eosinophils, but not on neutrophils. In addition, reverse transcription-polymerase chain reaction and Northern blot analysis showed that CD52 mRNA was constitutively expressed in eosinophils but not in neutrophils. Furthermore, expression of CD52 could be diminished in a dose-dependent manner by preincubation of eosinophils with phosphatidylinositol-specific phospholipase C, suggesting that CD52 on eosinophils is anchored to the membrane through a glycosylphosphatidylinositol (GPI) molecule. Whereas the phorbolester phorbol myristate acetate was able to downregulate the expression of CD52 on eosinophils in a dose-dependent manner, different eosinophil activating cytokines and chemotaxins had no effect. Cross-linking of CD52 by mouse anti-CD52 MoAb (IgG3) and humanized anti-CD52 MoAb (IgG1) with goat antimouse antibody and mouse antihuman antibody, respectively, dose-dependently resulted in an inhibition of reactive oxygen species production of eosinophils after stimulation with C5a, platelet-activating factor, and granulocyte-macrophage colony-stimulating factor. In summary, this study shows that the GPI-anchored antigen CD52 is not only a useful marker to distinguish eosinophils from neutrophils. The data point out a novel role of the CD52 antigen on human eosinophils that might be of clinical relevance, because cross-linking of this molecule will stop the destructive power of human eosinophils in the inflammatory tissue.

Antibodies, Monoclonal↗

PubMed1996

Identification of the antigen recognized by the monoclonal antibody 31D8.

The monoclonal antibody (mAb) 31D8 has previously been described to bind more avidly to functionally active neutrophils and proved to be useful as a differentiation marker of neutrophils. However, attempts to further characterize the antigen recognized by 31D8 have not been successful. Studying the altered Fcgamma-receptor expression of human neutrophils induced by granulocyte colony-stimulating factor (G-CSF) in vivo, we could demonstrate a parallel decrease in the expression of 31D8 and the CD16 antigen. Furthermore, 31D8 showed a binding pattern on leukocyte subsets similar to that of clustered CD16 antibodies, exhibiting identical cells in double-staining experiments. Preincubation of neutrophils with 31D8 resulted in a dose-dependent inhibition of the binding of immune complexes. A decreased expression of the 31D8 antigen was found on the same cell clones to the same extent as found for the 3G8 antigen on neutrophils from patient with paroxysmal nocturnal hemoglobinuria (PNH). Treatment of polymorphonuclear leukocytes (PMN) with PIPLC resulted in a dose-dependent decrease of mAb 31D8 binding, showing that the 31D8 antigen is phosphatidylinositolglycan (PIG)-anchored. Moreover, 31D8 competed with the binding of antibodies (such as mAb 3G8) directed against the binding site of FcgammaRIII for the Fc-part of IgG. However, this mAb did not influence the binding of a CD16 antibody (mAb B73.1) which recognizes an epitope elsewhere on the CD16 antigen. We conclude from our experiments that the mAb 31D8 binds with high avidity to fcgammaRIII (CD16 antigen). Furthermore, our data indicate that its binding site is most probably located at the binding site for the Fc-part of IgG.

Antibodies, Monoclonal↗

PubMed1995

Relapse of acute myelogenous leukemia during low dose interleukin-2 (IL-2) therapy. Phenotypic evolution associated with strong expression of the IL-2 receptor alpha chain.

BACKGROUND: Interleukin-2 (IL-2) has produced remissions in patients with solid tumors, predominantly malignant melanoma and renal cell carcinoma. Recently, clinical trials have assessed the therapeutic benefit of this cytokine in acute myelogenous leukemia (AML). However, little is known about the potential of IL-2 to promote the growth of leukemic cells in vivo. METHODS: A patient with acute myelocytic leukemia whose leukemic blasts displayed lymphoid (TdT+ and CD4+) and myeloid features (myeloperoxidase [MPO]+ and CD13+) is reported. The IL-2 receptor alpha chain (CD25 antigen) was present on 28.9% of his blasts. After entering complete remission with chemotherapy, he was treated on a protocol using IL-2 maintenance. RESULTS: Six weeks after beginning low-dose IL-2, his leukocyte count increased to 448,000/microliters with 86% blasts. The phenotype of these blasts was different from that at diagnosis with expression of the CD25 antigen and the CD33 antigen on 75.9% and 74.8 of the blasts, respectively. Furthermore, 30% of the cells were TdT+, whereas MPO was not detectable. CONCLUSION: The rapid course of relapse, phenotypic evolution, and the high expression of CD25 antigen on the blasts after IL-2 therapy raise the possibility that the cytokine therapy may have promoted the growth of leukemic cells.

Humans↗

PubMed1994

Evaluation of flow cytometric methods for diagnosis of chronic granulomatous disease variants under routine laboratory conditions.

Neutrophils from 50 pediatric patients with normal phagocyte functions, from 150 healthy adults, from 10 chronic granulomatous disease (CGD)-patients (4 CGD+), and from 18 X-linked carriers for CGD have been tested for their production of H2O2 using staining with dihydrorhodamine 123 and subsequent flow cytometry. Additionally, neutrophils from three patients with myeloperoxidase deficiency were assessed. Cells were activated to produce H2O2 by the phorbol ester phorbol-myristate-acetate (PMA) and by phagocytosis of Escherichia coli bacteria. To evaluate the sensitivity of the method, H2O2-production by neutrophils which was inhibited by different concentrations of diphenyljodonium (DPI) was measured. The results were compared to those from other methods (NBT-testing, cytochrome c-reduction, and especially chemiluminescence). Normal values and ranges of scatter profile were evaluated in terms of peak channel fluorescence: 97% > 700, x = 840 +/- 59 (S.D.), 97% < 890, for pediatric patients. Normal quantitative values also resulted from small blood samples of infants (< 1 year, n = 6, x = 830 +/- 52). For CGD+ (n = 4) the results were clearly far below the normal range. In indicating decreased production of reactive oxygen intermediates the method was at least as sensitive as lucigenin enhanced chemiluminescence. Cytochrome b558-expression of neutrophils from patients and healthy controls was established by flow cytometry following staining with the monoclonal antibody 7D5. The normal range was 97% > 485, 97% < 680, peak channel fluorescence. We conclude that flow cytometric routine diagnostics of CGD can easily enhance the reliability of recognition and the yield of information about this disease compared to conventional methods.

Adult↗

PubMed1994

Altered surface marker expression and function of G-CSF-induced neutrophils from test subjects and patients under chemotherapy.

We have previously reported an altered surface marker expression and chemotaxis of G-CSF-induced neutrophils from patients with severe congenital neutropenia. However, effects of G-CSF and influence of the underlying disease on neutrophils could not be discerned. In this study we have evaluated the effects of G-CSF on neutrophil phenotype and function in patients under chemotherapy and in healthy test subjects. We found a significantly enhanced expression of Fc gamma RI, CD14 and CD54 and a decrease in the level of Fc gamma RIII during G-CSF treatment. In addition, motility of G-CSF-induced neutrophils was significantly decreased. The effects were seen in patients under cytotoxic chemotherapy and in healthy test subjects. Surface marker alterations and neutrophil motility were affected by G-CSF administration in a dose-dependent manner. Kinetic studies on neutrophils from healthy test subjects demonstrated that all effects could be seen after a single administration of 300 micrograms G-CSF and began to appear within 4 h. Release of partially immature neutrophils from the bone marrow and indirect activation of these cells by G-CSF are discussed as possible reasons for the findings presented. They demonstrate that G-CSF has profound effects on neutrophil phenotype and function in vivo which might have clinical implications.

Antigens, Surface↗

PubMed1994

Changes in light-scatter profile, membrane depolarization and calcium mobilization of neutrophils induced by G-CSF in vivo.

To extend our studies about phenotypical and functional alterations of G-CSF-induced neutrophils we have evaluated their light-scatter profile, mobilization of intracellular calcium ([Ca2+]i) and membrane depolarization after stimulation. A significant increase in the forward scatter signals could be demonstrated in such neutrophils from patients with neutropenias of various origin and from healthy test subjects. This increase began 4 h and returned to normal 96 h after G-CSF injection in the latter group. We found an impairment of [Ca2+]i mobilization in neutrophils from patients with glycogen storage disease type IB after stimulation of these cells with fMLP. It was even more pronounced than in severe congenital neutropenia (SCN). However, [Ca2+]i fluxes were normal when ionomycin was used. Neutrophils from patients with cyclic neutropenia (cyNP) and chemotherapy-induced neutropenia (chNP) mobilized [Ca2+]i similar to those from healthy donors. Furthermore, we found a decreased percentage of neutrophils depolarizing after stimulation with fMLP and PMA in patients with SCN, whereas membrane depolarization was normal in patients with chNP and cyNP. All the alterations found here are suggested to be caused by a partial immaturity of the neutrophils, although in vivo activation and a direct effect of G-CSF on myeloid precursors might be involved.

Calcium↗

PubMed1993

Cyclosporine metabolite pattern in blood from patients with acute GVHD after BMT.

The cyclosporine (CYA) metabolite patterns in blood were evaluated in patients with liver dysfunction after allogeneic BMT. Fifty-five BMT patients were included in the study until discharge from hospital. Blood trough levels of CYA and 12 of its metabolites were quantified using HPLC. The patients were assigned to three groups: group I (no acute GVHD, n = 23), group II (acute GVHD of the skin and good liver function, overall acute GVHD: grade I: n = 18, grade II: n = 2) and group III (acute GVHD and liver dysfunction, overall acute GVHD: grade II: n = 2, grade III/IV: n = 8). Analysis of the trough blood concentrations of CYA and its metabolites revealed higher concentrations of metabolite AM19 in group III than in the other groups without reaching statistical significance. During acute GVHD of the liver, the metabolites AM19 (p < 0.01), AM1c9 (p < 0.05) and AM1A (p < 0.05) were significantly elevated compared with patients with normal liver function while CYA and all other metabolites did not differ. The CYA metabolite pattern in patients with acute GVHD and liver involvement was identical with that of liver graft patients during acute graft rejection, while the metabolite patterns of the patients without acute GVHD paralleled that of kidney grafted patients with normal liver function. Acute GVHD of the liver leads to an impaired elimination of CYA with increased blood concentrations of single CYA metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗