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Biomedical subjects

E Platzer

Publications and source records attributed to E Platzer.

At least 19 recordsLinked to original sources
PubMed2002

Randomized, controlled, dose-range study of Ro 25-8315 given before and after a high-dose combination chemotherapy regimen in patients with metastatic or recurrent breast cancer patients.

PURPOSE: To evaluate the safety, pharmacokinetics, and efficacy of three different dose levels of pegylated granulocyte colony-stimulating factor (Ro 25-8315) on progenitor cell mobilization and hematologic recovery in cancer patients. PATIENTS AND METHODS: Breast cancer patients (n = 36) were randomly assigned to receive before (part I) and after (part II) chemotherapy either a single-dose injection of Ro 25-8315 (20 microg/kg, n = 9; 60 microg/kg, n = 9; 100 microg/kg, n = 10) or a standard daily dose of filgrastim (part I, 10 microg/kg/d; part II, 5 microg/kg/d) (control group, n = 8). RESULTS: Overall, Ro 25-8315 was well tolerated. In part I, more progenitor cell mobilization was observed with Ro 25-8315 100 microg/kg. The peak of circulating CD34(+) cells was obtained at day +5 in the four groups, and the absolute neutrophil count (ANC) returned to less than 20 x 10(9)/L by day +15. In part II, high levels of circulating CD34(+) cells (> 20 cells/microL) were obtained in all four groups. The chemotherapy-induced neutropenia (< 1 x 10(9)/L) was similar in the four groups. Ro 25-8315 100 microg/kg was more effective than filgrastim in reducing the number of patients with an ANC less than 0.5 x 10(9)/L on day +12 after chemotherapy. CONCLUSION: A single injection of Ro 25-8315 100 microg/kg might be the optimal dose for steady-state peripheral-blood progenitor cell mobilization. A single injection of 20, 60, or 100 microg/kg could be as efficient as daily administration of filgrastim to correct chemotherapy-induced cytopenia. The optimal dose of Ro 25-8315 should be determined according to the planned chemotherapy regimen.

Adult↗
PubMed2001

Pharmacodynamics and pharmacokinetics of single doses of subcutaneous pegylated human G-CSF mutant (Ro 25-8315) in healthy volunteers: comparison with single and multiple daily doses of filgrastim.

Ro 25-8315 is produced by conjugation of rhG-CSF mutant with polyethylene glycol (PEG). The purpose of this study was to examine the pharmacodynamics and pharmacokinetics of Ro 25-8315 in comparison with Filgrastim (rhG-CSF). Subjects received single subcutaneous doses of Ro 25-8315 ranging from 10 to 150 microg/kg using a double-blind, randomized, placebo-controlled design. Filgrastim was administered as a single dose (5 or 10 microg/kg) and, following a 14-day washout period, daily for 7 days. Ro 25-8315 increased absolute neutrophil count (ANC) by 6- to 8-fold and CD34+ cell count more than 30-fold at the highest doses tested. Single doses (60-150 microg/kg) of Ro 25-8315 and multiple doses of Filgrastim had similar effects on ANC and CD34+, although Ro 25-8315 had a greater effect on CFU-GM. The pharmacokinetics of Ro 25-8315 were dose-dependent, with peak concentrations and area under the serum concentration-time curve (AUC) increasing 100-fold over the range of doses studied. Time to reach peak concentration (T(max)) and half-life of Ro 25-8315 averaged 20-30 hr at all doses, approximately three times longer than with Filgrastim. Adverse events were not serious and occurred with similar frequency with both products. Pegylation of rhG-CSF mutant results in more desirable pharmacokinetic properties and a longer duration of action with effective increases in ANC and measures of peripheral blood progenitor cell mobilization for at least 1 week.

Adult↗
PubMed1994

Differential effects of transferrin receptor antibodies on growth and receptor expression of human lymphocytic and myelocytic cell lines.

J64, a monoclonal antibody against the human transferrin receptor, has been shown to induce interleukin-2 production by HUT78 cells. It also causes growth inhibition of several cell lines and stimulated lymphocytes. These effects were also present using transferrin-free culture conditions. In this paper, we dissect cell membrane and intracellular events after binding of J64 and other transferrin receptor antibodies. Incubation of HUT78 and several other cell lines with J64 resulted in an increased number of receptor molecules expressed on the cell surface in contrast to a downmodulation seen with other monoclonal antibodies to the transferrin receptor. This upregulation after treatment with J64 was not due to an increased concentration of transferrin receptor mRNA in these cells or a higher protein synthesis rate. We therefore suggest that J64 causes a redistribution of transferrin receptor molecules from intracellular pools to the cell surface. Additional experiments investigating signal transduction mechanisms revealed no influence of J64 on intracellular Ca2+ concentrations or translocation of protein kinase C. However, an increase of transferrin receptor phosphorylation was seen in HL60 cells after treatment with phorbolester or J64. This phosphorylation of the transferrin receptor might be a signal transduction pathway involved in activation and growth control.

Antibodies, Monoclonal↗
PubMed1994

Randomized study of recombinant human granulocyte colony-stimulating factor after high-dose chemotherapy and autologous bone marrow transplantation for high-risk lymphoid malignancies.

PURPOSE: The aim of this prospective randomized trial was to examine the efficacy and safety of filgrastim after high-dose chemotherapy and autologous bone marrow transplantation (ABMT). PATIENTS AND METHODS: Patients with poor-risk non-Hodgkin's lymphoma or relapsed Hodgkin's disease were treated in a randomized, open-label trial to study the use of filgrastim as an adjunct to high-dose chemotherapy and ABMT. Of 43 assessable patients, 19 were randomized to receive filgrastim by continuous subcutaneous infusion at a dose of 10 micrograms/kg/d, 10 to filgrastim 20 micrograms/kg/d, and 14 to a parallel control group that received no filgrastim after ABMT. RESULTS: For all filgrastim-treated patients analyzed together, the median time to neutrophil recovery > or = 0.5 x 10(9)/L after the day of ABMT was significantly accelerated to 10 days compared with 18 days in control patients (P = .0001). The median number of platelet transfusions was identical in both groups. Clinical parameters, including the median number of days with fever (1 v 4, P = .0418) and neutropenic fever (5 v 13.5, P = .0001) were significantly shorter in the filgrastim than in the control group. The number of days on intravenous antibiotics and duration of hospitalization were also shorter in the treated groups; however, the differences did not reach statistical significance. For patients treated with the two different dose levels of filgrastim, the neutrophil recovery and clinical results were similar. Filgrastim-associated toxicity appeared to be minimal, with five adverse events considered at least possibly related to filgrastim: two in the higher-dose group and three in the lower-dose group. All of these were rated moderate, except one case of severe bone pain that did not preclude continued filgrastim treatment at a lower dose. Survival and relapse-free survival were similar for control and filgrastim-treated patients. CONCLUSION: Taken together, the results of this first randomized study support the role of filgrastim given as an adjunct to ABMT in accelerating neutrophil recovery, as well as in reducing treatment-related morbidity and overall duration of the treatment procedure.

Adolescent↗
PubMed1993

Involvement of the high-affinity receptor for IgG (Fc gamma RI; CD64) in enhanced tumor cell cytotoxicity of neutrophils during granulocyte colony-stimulating factor therapy.

Three different classes of Fc receptors for IgG (Fc gamma R) are currently distinguished in humans, of which polymorphonuclear phagocytes (PMN) normally express both low-affinity receptor classes--Fc gamma RII (CD32) and Fc gamma RIII (CD16). During therapy with granulocyte colony-stimulating factor (G-CSF), neutrophils from patients with various malignancies and different hematologic disorders were found to additionally express high levels of the receptor with high affinity for IgG (Fc gamma RI; CD64). For these patients, the relative fluorescence intensity (rFI) for Fc gamma RI was 5.3 (range, 1.7 to 10.3; n = 19), compared with 1.0 (range, 1.0 to 1.1; n = 8) for healthy donors. The expression of Fc gamma RI during G-CSF therapy could be confirmed by using a panel of six CD64-specific antibodies, and by showing mRNA for Fc gamma RI. So far, three genes for Fc gamma RI have been identified, encoding four distinct transcription products. By reverse transcriptase-polymerase chain reaction technology, transcripts for both membrane-associated isoforms (hFc gamma RIa and hFc gamma RIb2) could be detected. The functional activity of Fc gamma RI on PMN during G-CSF therapy was shown by measuring binding of monomeric human IgG and antibody-dependent cellular cytotoxicity (ADCC). Thus, Fc gamma RI-positive neutrophils displayed enhanced ADCC activity to glioma (A1207), squamous cell (A431), and ovarian (SK-ov3) carcinoma cell lines. The involvement of Fc gamma RI in this increased cytotoxic activity was shown by blocking Fc gamma receptors with monoclonal antibodies, and by using F(ab')2 x F(ab')2-bispecific antibodies with specificities against tumor-related antigens and Fc gamma RI, resulting in solely Fc gamma RI-mediated cytotoxicity. Therapeutically, this additional Fc receptor on PMN may increase the efficacy of experimental antibody therapy.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1992

Stable growth transformation of human T lymphocytes by herpesvirus saimiri.

Herpesvirus saimiri induces T-cell lymphomas in various species of New World monkeys and in rabbits, and it is able to immortalize monkey T lymphocytes in vitro. Sequences responsible for these effects have been localized to a region of the genome that varies significantly among the virus subgroups A, B, and C. We now report that infection of human blood lymphocytes and thymocytes with strains of subgroup C, in contrast to viruses of the other subgroups, yields continuously proliferating T-cell lines with the phenotype of mature CD4- or CD8-positive cells. Infection with strains of Herpes-virus saimiri subgroup C can thus be used to generate human T-cell lines for a variety of immunological and developmental studies.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

Functional characterization of tumor-infiltrating lymphocytes, lymph-node lymphocytes and peripheral-blood lymphocytes from patients with breast cancer.

Mononuclear cell infiltration is frequently seen within human solid tumors. Effector cells within the tumor site usually fail to exhibit cytotoxic or natural killer activity when freshly isolated; however, they develop potent and sometimes specific cytotoxicity after expansion in IL2. Thus, local tumor environment may influence lymphocyte function. In our study, we disaggregated human breast-cancer and lymph-node tissue to obtain lymphocyte-enriched cell fractions. Besides phenotypic analysis, functional characterization with regard to proliferation and cytokine production of tumor-infiltrating lymphocytes (TIL), peripheral-blood lymphocytes (PBL) and lymph-node lymphocytes (LNL) was the aim of our study. TIL showed an enrichment of CD8+ cells with a corresponding decrease in CD4+ cells in comparison with PBL and LNL. In response to PHA, TIL showed decreased 3H-thymidine uptake, but TIL were significantly stimulated by rhIL2. TIL produced low levels of IL2, TNF and IFN gamma upon mitogen/phorbol ester stimulation, while PBL produce high levels of TNF and IFN gamma but low levels of IL2. Under the same experimental conditions, LNL produce high levels of TNF and IL2 but low levels of IFN gamma. Mitogen-mediated TNF secretion was increased after addition of autologous tumor cells in TIL and LNL, whereas IFN gamma secretion tended to be suppressed. Our results indicate different patterns of activities of TIL, LNL and PBL from breast-cancer patients.

Breast Neoplasms↗
PubMed1991

Neutrophils express the high affinity receptor for IgG (Fc gamma RI, CD64) after in vivo application of recombinant human granulocyte colony-stimulating factor.

Fc receptors are important effector molecules of neutrophilic granulocytes (polymorphonuclear neutrophils [PMN]), connecting phagocytic cells and the specific immune response. Neutrophils from healthy donors express the low-affinity receptors for IgG Fc gamma RII (CD32) and Fc gamma RIII (CD16), but not the high-affinity receptor Fc gamma RI (CD64). The latter has been found on neutrophils from patients with certain bacterial infections and can be induced in vitro after incubation with interferon-gamma. We show here that neutrophils strongly express Fc gamma RI after in vivo application of recombinant human granulocyte colony-stimulating factor (rhG-CSF). PMN from patients receiving rhG-CSF displayed higher cytotoxicity against Daudi lymphoma cells in vitro compared with control patients and with healthy donors. Fab fragments against Fc gamma RII (monoclonal antibody [MoAb] IV.3) inhibited neutrophil-mediated cytotoxicity of healthy donors but not of patients during rhG-CSF therapy. Therefore, expression of Fc receptors by PMN was investigated by flow cytometry and the mean fluorescence intensity (MFI) was compared. After staining with MoAb 32.2 against Fc gamma RL, the median MFI of neutrophils from G-CSF patients (median, 4.78; range, 2.40 to 8.50; n = 5) was significantly higher (P = .002 and P = .001, respectively) than the median MFI of patients not receiving G-CSF (median, 1.23; range, 1.01 to 1.58; n = 6) and the median MFI of healthy donors (median, 1.04; range, 0.67 to 1.12; n = 6). Fc gamma RI disappeared after the discontinuing of the G-CSF injections, but was reinduced during the next treatment cycle with rhG-CSF. The high expression of Fc gamma RI during rhG-CSF therapy correlated with enhanced cytotoxicity. In vitro incubation with rhG-CSF also enhances cytotoxicity, but only minor increments in Fc gamma RI expression were observed. Thus, during in vivo application of rhG-CSF neutrophils acquire an additional potent receptor for mediating tumor cell killing in vitro by induction of the high-affinity receptor for IgG (Fc gamma RI, CD64).

Antibodies, Monoclonal↗
PubMed1991

Persistence of selectable herpesvirus saimiri in various human haematopoietic and epithelial cell lines.

Herpesvirus (h.) saimiri, an infectious agent of squirrel monkeys, is capable of persisting in T lymphocytes of various primate species. It has been used as a vector for the functional analysis of regulatory genes in primary human T lymphocytes. As it is not yet known whether other cell types are capable of supporting viral persistence, various human cell lines were investigated using selectable h. saimiri recombinants. The lines chosen represent cells from the epithelium and connective tissue as well as from all haematopoietic lineages, i.e. cells of B and T lymphoid origin as well as myeloid-, fibroblast- and carcinoma-derived cultures converted to Geneticin or hygromycin B resistance, and harbouring episomal DNA of the selectable recombinants. The Burkitt's lymphoma-derived cell line Raji also contained simultaneously persisting episomes of the Epstein-Barr virus. Most of the cell cultures except a pancreatic carcinoma line and foreskin fibroblasts did not produce infectious virus. These observations show that a herpesvirus genome can persist episomally in a broad range of cultured cell types. The variety of infectable cell types and species suggests the presence of a widely distributed and well conserved virus receptor for h. saimiri. Thus the h. saimiri genome could be applied more generally as a vector.

Blotting, Northern↗
PubMed1990

Effects of IFN on human eosinophils in comparison with other cytokines. A novel class of eosinophil activators with delayed onset of action.

Extracellular killing is regarded as one of the main functions of eosinophils. Therefore, a cytotoxicity assay against antibody-coated Daudi-lymphoma cells was established to measure cytokine effects on peripheral blood eosinophils from healthy volunteers. Optimal time of exposure to cytokines and half optimal concentrations (EC50) were determined and the capability of various cytokines to enhance cytotoxicity of eosinophils was compared. Thus, after 24 h with cytokine, the highest activation of eosinophils was observed with recombinant human rhIFN-gamma (EC50 = 0.2 U/ml), followed by the known activators of eosinophils recombinant human granulocyte/macrophage CSF (rhGM-CSF), rhIL-3, and murine IL-5 (mIL-5). rhIFN-alpha and natural human IFN-beta (nhIFN-beta) enhanced cytotoxicity as well. On the other hand, in short term assays, eosinophils were not stimulated by IFN and the strongest stimulator was rhGM-CSF (EC50 = 0.2 U/ml), followed by rhIL-3, mIL-5, rhTNF, and rhIL-4. With rhTNF-alpha enhancement was more pronounced on freshly isolated eosinophils (EC50 = 0.6 U/ml) and declined with time. No significant stimulation was detected with rhG-CSF, rhIL-1 beta, rhIL-2, rhIL-6, and rhIL-8. On neutrophils, rhIL-8 enhanced cytotoxicity, but the stimulation was weak in relation to other neutrophil activators. Studies on the mechanism of cytotoxic activity revealed that cytotoxicity required opsonization of targets with specific antibody. FMF analysis was performed demonstrating that freshly isolated eosinophils express Fc-gamma RII (CD32), small amounts of Fc-gamma RIII (CD16), but not Fc-gamma RI (CD64). In experiments with blocking antibodies to Fc-gamma R cytotoxicity was restricted to Fc-gamma RII. Expression of Fc-gamma RII was not enhanced by rhGM-CSF, rhTNF-alpha, and mIL-5, but a significant increase in the number of positive cells was observed after incubation with rhIFN-gamma for 24 h (p less than 0.05). In addition, enhanced viability of eosinophils was observed when cultured in the presence of rhIFN-gamma, rhIFN-alpha, rhGM-CSF, and rhTNF-alpha, but not of rhG-CSF and rhIL-2. Thus, IFN appear to be another class of activators of eosinophils, characterized by their delayed type of action.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1990

A quantitative colorimetric method to evaluate the functional state of human polymorphonuclear leukocytes.

The colorimetric assay previously described by Mosmann for the measurement of cell viability and proliferation has been modified for the assessment of the functional state of human polymorphnuclear cells (PMNs). The ability of PMNs to reduce the tetrazolium salt MTT to formazan reflects directly the degree of stimulation induced by various agents. The underlying mechanism of MTT-reduction to formazan seems to be similar to that of nitroblue tetrazolium (NBT)-reduction. In contrast to the NBT-reduction assay, the formazan produced from MTT can easily be measured by an ELISA reader. Parallel experiments revealed a qualitative correlation between the concentration of formazan produced from MTT and the concentration of cytochrome C reduced by PMNs. Although oxidative burst may not be the actual lytic mechanism in cellular cytotoxicity of PMN, we also observed an association between MTT-reduction capacity and the cytotoxic activity of PMNs from normal donors in antibody dependent cellular cytotoxicity. Our results indicate that the MTT-reduction assay can be employed to estimate the functional state of polymorphnuclear granulocytes.

Cell Division↗
PubMed1990

A simple assay for quantifying the inducible adherence of neutrophils.

By making use of the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reducing ability of stimulated human neutrophils, we developed an alternative method to quantify the adherence of neutrophils in vitro. After discarding non-adherent neutrophils, the adherent cells were exposed to MTT solution containing 10 ng/ml phorbol 12-myristate 13-acetone (PMA). Subsequently, MTT reduced by this simultaneous stimulation was measured optically and used to calculate percent of adhesion. In these experiments, heat-inactivated autologous serum and tumor necrosis factor alpha (rhTNF-alpha) were observed to promote the adherence to polystyrene surfaces. In contrast, minimal or no effects on neutrophil adherence were achieved in case of treatment with native autologous serum, recombinant human granulocyte colony stimulating factor (rhG-CSF), recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF), or recombinant human interferon gamma (rhIFN-gamma).

Biological Assay↗
PubMed1990

Effect of interleukin 3 on cytosine arabinoside-mediated cytotoxicity of leukemic myeloblasts.

The concept of biologic modification of proliferation and differentiation of myeloid leukemia cells has attracted much attention over the past years. One promising strategy involves the recruitment of leukemic cells into the cell cycle by hematopoietic growth factors in combination with cycle-specific cytotoxic drugs. Because cytosine arabinoside (Ara-C), which targets only cells in S-phase of the mitotic cell cycle, is included in most chemotherapeutic regimens for the treatment of acute myelogenous leukemia, we explored the hypothesis that the recruitment of quiescent immature leukemic blasts into the cell cycle by the early acting growth factor interleukin 3 (IL-3) can increase the efficacy of Ara-C for kill of leukemic stem cells. We show that IL-3 increases the fraction of blasts in S-phase, as assessed by DNA histogram analysis with propidium iodide staining, leading to an enhancement of kill of clonogenic blast cells when combined with Ara-C. Expression of the protooncogenes c-myc, c-fms, and c-fos, known to be linked to cellular proliferation and differentiation, was also altered by IL-3 in Ara-C-treated cultures, further substantiating the role that IL-3 plays as an enhancer of the cytotoxicity of Ara-C.

Antigens, CD↗
PubMed1989

Human hemopoietic growth factors.

Hematopoiesis is regulated by a complex network of soluble stimulators and inhibitors, as well as by cellular interactions in the bone marrow microenvironment. Progress in molecular biology and protein biochemistry has provided a number of hemopoietic growth factors that are now available in large quantities for in vitro and in vivo studies. Several of them seem to hold great promise for patients suffering from insufficient hematopoiesis of various causes. This review focuses on new developments in the understanding of hemopoietic growth factors activity, and on recent clinical data.

Colony-Stimulating Factors↗
PubMed1988

Human granulocyte colony stimulating factor: effects on human long-term bone marrow cultures.

Human granulocyte colony stimulating factor (G-CSF) was previously shown to support the survival and proliferation of early myeloid progenitors (pre-CFU) that are capable of generating more mature CFU-GM progenitor cells. To evaluate the scope of action of G-CSF in the hierarchy of hematopoietic stem cells, we studied the effects of recombinant G-CSF (rhG-CSF) on long-term cultures of normal human bone marrow cells (LTBMC). We found that rhG-CSF predominantly influenced initial cell proliferation and expansion of CFU-GM progenitor cells in LTBMC before establishment of a confluent adherent layer. In rhG-CSF-treated LTBMC, the stromal cell layer was associated with a higher proliferative capacity and progenitor cell content as compared to control cultures. This effect was pronounced early after layer confluence and was gradually lost with culture time. rhG-CSF did not alter the duration of the productive phase of LTBMC, suggesting that it may not be active on the hematopoietic stem cells responsible for LTBMC propagation. Alternatively, stromal cells may exert tight regulatory control over progenitor cells, even in the presence of rhG-CSF.

Bone Marrow Cells↗
PubMed1986

Recombinant human granulocyte colony-stimulating factor: effects on normal and leukemic myeloid cells.

Experiments were conducted to isolate and characterize the gene and gene product of a human hematopoietic colony-stimulating factor with pluripotent biological activities. This factor has the ability to induce differentiation of a murine myelomonocytic leukemia cell line WEHI-3B(D+) and cells from patients with newly diagnosed acute nonlymphocytic leukemia (ANLL). A complementary DNA copy of the gene encoding a pluripotent human granulocyte colony-stimulating factor (hG-CSF) was cloned and expressed in Escherichia coli. The recombinant form of hG-CSF is capable of supporting neutrophil proliferation in a CFU-GM assay. In addition, recombinant hG-CSF can support early erythroid colonies and mixed colony formation. Competitive binding studies done with 125I-labeled hG-CSF and cell samples from two patients with newly diagnosed human leukemias as well as WEHI-3B(D+) cells showed that one of the human leukemias (ANLL, classified as M4) and the WEHI-3B(D+) cells have receptors for hG-CSF. Furthermore, the murine WEHI-3B(D+) cells and human leukemic cells classified as M2, M3, and M4 were induced by recombinant hG-CSF to undergo terminal differentiation to macrophages and granulocytes. The secreted form of the protein produced by the bladder carcinoma cell line 5637 was found to be O-glycosylated and to have a molecular weight of 19,600.

Animals↗