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U Oelschlägel

Publications and source records attributed to U Oelschlägel.

16 recordsLinked to original sources
PubMed2004

P-glycoprotein-mediated drug efflux is a resistance mechanism of chronic myelogenous leukemia cells to treatment with imatinib mesylate.

Imatinib (Glivec), STI571) is an intracellular acting drug that demonstrates high activity against BCR-ABL-positive chronic myelogenous leukemia (CML) or acute lymphoblastic leukemia (ALL). However, many patients, especially with advanced disease, develop drug resistance. Here, we show by a novel high-performance liquid chromatography-based method that intracellular levels of imatinib decrease in P-glycoprotein (Pgp)-positive leukemic cells. In a model of K562 cells with gradually increasing Pgp expression, a Pgp-dependent decline of intracellular imatinib levels was observed. Decreased imatinib levels were associated with a retained phosphorylation pattern of the Bcr-Abl target Crkl and loss of effect of imatinib on cellular proliferation and apoptosis. The modulation of Pgp by cyclosporin A (CSA) readily restored imatinib cytotoxicity in these cells. Finally, we provide first data showing a biological effect of Pgp modulation in the imatinib treatment of a patient with BCR-ABL-positive ALL. MDR1 overexpression must therefore be considered as an important clinical mechanism in the diversity of resistance development to imatinib treatment.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Large-scale immunomagnetic selection of CD14+ monocytes to generate dendritic cells for cancer immunotherapy: a phase I study.

Dendritic cells (DC) are professional antigen-presenting cells that are widely used in the experimental immunotherapy of cancer. For clinical use GMP-like protocols for the preparation of functionally active dendritic cells (DC) in large numbers and at high purity are needed. However, the currently available protocols have certain disadvantages. In this study we tested the generation and clinical applicability of DC from monocyte preparations produced by immunomagnetic CD14(+) selection using a semiautomated clinical scale immunomagnetic column. Peripheral blood mononuclear cells (PBMC) of 10 patients with metastatic solid tumors were used. With the immunomagnetic separation, we obtained a cell suspension of high CD14(+) purity (median 97.4%, range 94.9-99.0) with a high monocyte yield (median 82.3%, range 63.9-100.0). Differentiation of CD14(+) cells into mature monocyte-derived DC was induced by incubation with IL-4, GM-CSF, TNF-alpha, PGE(2), IL-1 beta, and IL-6. Mature DC showed a high expression of CD83, HLA-DR, and the co-stimulatory molecules CD80 and CD86. Overall CD83(+) yield was 12.1% (range 4.0-29.4). Allogeneic T stimulatory capacity could be demonstrated for all DC preparations in proliferation assays. No significant differences in marker expression or T cell stimulation was detected between fresh DC and those derived from cryopreserved immature DC. Clinical administration of autologous DC by three different parenteral routes was tolerated by all 10 patients without systemic signs of toxicity. Our results indicate that immunomagnetic isolation of CD14(+) monocytes using the CliniMACS device is a suitable method for clinical-scale generation of functional DC under GMP-grade conditions. The selection can be performed in a closed system. Therefore, immunomagnetic CD14(+) selection can be seen as an alternative way to generate DC for clinical tumor vaccination protocols.

Adult↗
PubMed2002

Detection of relapse by sequential monitoring of chimerism in circulating CD34+ cells.

Relapse of the underlying malignant disease represents one of the major causes of treatment failure in patients treated with stem cell transplantation, especially in patients with acute leukemia. Detection of minimal residual disease (MRD) after allogenic stem cell transplantation (SCT) is important to schedule therapeutic intervention, e.g. donor lymphocyte infusion. We asked, whether chimerism analysis in circulating CD34+ cells might be a feasible method to monitor MRD in patients after allogeneic SCT. Eighty-seven patients undergoing allogeneic SCT were prospectively analyzed. CD34+ cells were prepared from peripheral blood samples and sorted after immunomagnetic preenrichment. Results were correlated to overall chimerism and results of nested RT-PCR for the bcr-abl rearrangement in Ph1-cases. In the 87 patients a median of 8 analyses (range 2-22) covering a median period of 295 days (range 28-1152) were performed. A hematological relapse was observed in 22/84 engrafting patients (26%). In twenty patients, the relapse was detected in the CD34+ fraction, in 14 of these patients, donor chimerism in CD34+ cells decreased 12-97 days (median 52 days) before the clinical diagnosis. In two cases, CD34+ chimerism failed to demonstrate the relapse. In patients with relapsing CML, the decrease of donor CD34+ cells was associated with reappearance of bcr-abl transcripts. Treatment (reduction of immunosuppression, DLI or STI571) was associated with an increase of donor derived CD34+ cells and clearance of bcr-abl positive cells. Sequential chimerism analysis in CD34+ cells is feasible and sensitive, allowing early detection of relapse and monitoring of therapeutic intervention. This method appears especially useful in patients with high risk leukemia lacking other markers for detection of MRD.

Antigens, CD34↗
PubMed2001

Platelet-associated tissue factor contributes to the collagen-triggered activation of blood coagulation.

The extravascular localization of tissue factor (TF), the central initiator of coagulation, is thought to ensure that thrombus formation is prevented in the intact vessel. We observed that during a 5-min stimulation of human blood with collagen (type I), TF antigen appeared on the surface of platelets adhering to leukocytes. The rapidly presented intravascular TF was competent to start the coagulation cascade. The isolated platelets from healthy donors contained appreciable amounts of the TF protein, while no TF antigen was detected in the neutrophils and rapidly isolated monocytes. Direct interactions with the neutrophils and monocytes were apparently necessary to activate the platelet-associated TF. This was most likely mediated by inactivation of tissue factor pathway inhibitor through leukocyte elastase. In summary, the leukocyte-elicited activation of the platelet TF participates in the rapid initiation of coagulation by collagen.

Adult↗
PubMed2001

Sequential monitoring of chimerism and detection of minimal residual disease after allogeneic blood stem cell transplantation (BSCT) using multiplex PCR amplification of short tandem repeat-markers.

Sequential analysis of chimerism after allogeneic blood stem cell transplantation (BSCT) has been shown to be predictive for graft failure and relapse. We have explored the impact of a novel approach for the quantitative determination of chimerism using a commercial PCR assay with multiplex amplification of nine STR-loci and fluorescence detection. The feasibility was studied in 121 patients transplanted from related or unrelated donors. Follow-up investigation was performed in 88 patients. Twenty-eight of these patients had received a transplantation after dose-reduced conditioning therapy. Results were compared to data obtained by FISH analysis in a subgroup of patients receiving grafts from sex-mismatched donors. The analysis was possible in all patients, the median number of informative alleles was 4 (range 1-8) compared to 7 (range 1-9) in the related and unrelated situation, respectively. A good correlation was seen in 84 samples from 14 patients analyzed in parallel with STR-PCR and FISH. Decreasing values of donor chimerism were detected prior to or concomitantly with the occurrence of graft failure and relapse of disease in all patients investigated prospectively. Using FACS-sorted material, eg peripheral blood CD34+ cells, the assay permitted the detection of residual recipient cells with high sensitivity (down to one CD34+ Kasumi cell in 40,000 normal WBC). Evaluation of the inter-laboratory reproducibility revealed that in 20 samples analyzed in three different centers, the median coefficient of variation was 2.1% (range 0.7-9.6%). Taken together, the results support the use of the test as a valuable tool in the follow-up of patients undergoing allogeneic BSCT. In cases lacking PCR-detectable disease-specific gene products, this assay may represent an alternative to recently established real-time PCR methods.

Adolescent↗
PubMed2000

Shift of aberrant antigen expression at relapse or at treatment failure in acute leukemia.

The flow cytometric detection of aberrant antigen expression is one method proposed for the quantification of minimal residual disease (MRD) in acute leukemias. The present study was designed to investigate the stability of the aberrant antigen expression at relapse or at treatment failure of initial chemotherapy. For this purpose, multiparameter immunophenotyping with a panel of 15 monoclonal antibodies was used at diagnosis as well as at relapse (43 patients with overall 65 aberrations) and at treatment failure (35 patients with overall 66 aberrations). There was a significant decrease in the percentage of the initially described aberrant antigen expression on leukemia blasts at relapse (P = 0.001; n = 65) as well as at treatment failure (P = 0.0001; n = 66) considering all aberrations in the whole leukemia population. Concerning only patients with acute myelogenous leukemia (AML), significant decreases in the aberrant expression could be detected at relapse (P = 0.031; n = 42) and at treatment failure (P = 0.0001; n = 52). The changes in patients with acute lymphoblastic leukemia (ALL) were significant only at relapse (P = 0.006; n = 23). Initially, the most informative aberration was not detectable in four patients at relapse and in seven patients at treatment failure. A decrease of under 50% of the initial value was observed in another 8 patients at relapse and in 10 patients at treatment failure. In further studies assessing the detection of aberrant antigen expression for MRD, quantification of the relapses should be explicitly analyzed regarding the persistence of the initially described aberrant antigen expression.

Adult↗
PubMed1999

Stable engraftment after megadose blood stem cell transplantation across the HLA barrier: the case for natural killer cells as graft-facilitating cells.

BACKGROUND: The case of a patient with chronic myelogenous leukemia who underwent transplantation with highly purified CD34+ peripheral blood stem cells from his two-antigen-mismatched mother is reported. No graft-versus-host disease has been observed so far and stable engraftment has been documented until day 100. METHODS: Weekly analysis of chimerism in different cellular subsets was performed using a quantitative polymerase chain reaction assay for nine short tandem repeat markers in leukocytes sorted by fluorescence-activated cell sorting. RESULTS: No donor CD4+ or CD8+ T cells have been detected up to 3 months after transplantation, whereas a rapid increase of donor CD56+ natural killer (NK) cells was observed in parallel with circulating donor CD34+ progenitors and myeloid cells. CONCLUSIONS: Because the graft contained virtually no T and NK cells, we believe the rapid in vivo generation of NK cells supported stable engraftment across the HLA barrier. The differentiation of CD34+ progenitors into NK cells might be a distinct feature of megadose stem cell transplants.

Adult↗
PubMed1999

Detection of residual aneuploid leukemic cells by "continuous gating".

BACKGROUND: A new method for the detection of residual aneuploid leukemic cells in bone marrow by flow cytometry is described. This method is based on the analysis of FCM derived list-mode-datasets with a new software called "Continuous Gating". The program is able to decrease the detection level of aneuploid tumor cells by analyzing groups of cells with comparable antigen density and scatter properties. METHODS: Aneuploid acute lymphocytic leukemia cells with a known CD34 expression were diluted with diploid bone marrow cells to a concentration of 10, 1, 0.1, 0.05, and 0.01%. Each sample was measured in a FACScan flow cytometer, after staining with CD34 Moab and propidium iodide. Listmode-data were analyzed with the new "Windows"-based "Continuous Gating" software. A gate was set in the DNA parameter, defining the channels in which the aneuploid G0/G1-peak of possible residual tumor-cells should be found. Ten thousand overlapping gates of size 200 x 200 channels (out of 1,023 x 1,023 channels) were set automatically by the program into the side-scatter (SSC)/CD34 dot-plot, calculating the percentage of aneuploid G0/G1-phase cells for every specific gate. RESULTS: The results are plotted in a contour-plot. In dot-plot gates with less than 20 cells, the calculation of the percentage of aneuploid cells was declared invalid and the area in the contour-plot was marked. Detection of residual aneuploid cells, based on a defined expression of CD34 and granularity (SSC), was possible down to a contamination of 0.1%. CONCLUSIONS: The new "Continuous Gating" software can be used for the automated detection of aneuploid leukemic cells, if the density of a certain surface-marker is slightly different from normal cells.

Adult↗
PubMed1999

Relations between IL-3-induced proliferation and in vitro cytokine secretion of bone marrow cells from AML patients.

The influence of IL-3 on the bone marrow cells of 53 patients with acute myeloid leukaemia (AML) was investigated after 72 h suspension in cultures by analysing the proliferation of blasts and the secretion of cytokines. The titres of IL-1beta IL-6, TNF-alpha and IL-3 were measured in the supernatants of these cultures with ELISA tests. Comparing the percentage of cells in S-phases of control cultures and cultures with IL-3, the leukaemias were divided into two growth pattern groups: IL-3-insensitive (n=19) and IL-3-sensitive (n=34) leukaemias. The IL-3-insensitive AML cells show a greater ability for autonomous growth, first by the increase of S-phase in the control culture compared with the S-phase in vivo (P=0.0486) and second, by the higher constitutive secretion (control culture) of IL-1beta P =0.0004), IL-6 ( P =0.0395) and TNF-alpha P=0.0005). The IL-3-induced secondary cytokine secretion is also different in the two growth pattern groups. Whereas in the IL-3-insensitive AML cells a moderate increase of IL-1beta (1.48-fold increase) was present, in the IL-3-sensitive AML cells a 4.72-fold increase of IL-1beta 2.71-fold increase of IL-6 and 11.81-fold increase of the TNF-alpha titre could be detected. Overall, the data show an inverse correlation between the ability of AML cells to respond to IL-3 with increase of an S-phase and the constitutive secretion of IL-1beta, II-6 and TNF-alpha. A further effect of IL-3 is the induction of secondary cytokine secretion in the bone marrow of IL-3-sensitive growing AML cells.

Acute Disease↗
PubMed1999

A new PCR MIMIC strategy to quantify low mdr1 mRNA levels in drug resistant cell lines and AML blast samples.

Determination of the MDR-phenotype in patients suffering from AML is an important hallmark of treatment outcome but is often complicated by technical problems in P-gp assessment. A PCR-MIMIC strategy was employed to construct PCR-fragments for a competitive and quantitative mdr1 reverse transcription-PCR-assay. Using K562 cells, which had been selected for drug resistance to the epipodophyllotoxin VP16, a stepwise increase of mdr1 levels depending on the concentration of VP16 was shown with the MIMIC technique. Comparison of mdr1 levels in drug selected K562 cells with the corresponding levels for P-gp and functional data indicated a mRNA threshold that has to be exceeded for the full expression of the MDR-phenotype. Subsequently mdr1 levels of 34 samples of de novo acute myeloid leukemia were determined with the PCR-MIMIC strategy. Ten patient samples could be identified with elevated mdr1 levels which were substantially lower than the levels observed in the MDR-cell line K 562 0.7 microM VP16. Outcome analysis revealed that eight of the ten patients had an unfavourable prognosis and did not achieve CR after induction chemotherapy. Coexpression of mdr1 and CD 34 was not associated with CR in all examined cases. Moreover all these patients had unfavourable cytogenetic aberrations. These data indicate a sensitive technique with applicability in patient material.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Flow cytometric DNA quantification in immunophenotyped cells as a sensitive method for determination of aneuploid multiple myeloma cells in peripheral blood stem cell harvests and bone marrow after therapy.

The simultaneous measurement of DNA content and myeloma-related antigens (B-B4 or CD38) by flow cytometry is proposed as a method for the detection of aneuploid plasma cells in peripheral blood stem cell (PBSC) harvests and in bone marrow after therapy. In 30 patients with initially detected aneuploid myeloma cells we evaluated the bone marrow after therapy and in eight of these patients 23 PBSC harvests were analyzed. In 13 of 23 PBSC harvests aneuploid myeloma cells were detectable (range: 0.02-0.63%). In the bone marrow of the 30 patients aneuploid plasma cells were detectable in all samples after chemotherapy (range: 0.12-35.70%) and after autologous PBSC transplantation in two of three patients (0.21% and 0.03%). Furthermore the relationship between diploid and aneuploid plasma cells can be evaluated. In the PBSC harvests the percentage of aneuploid plasma cells is significantly lower than that of diploid plasma cells (P=0.006). In contrast, in bone marrow the aneuploid plasma cells are predominant in most patients even after therapy (24 of 30 patients; P=0.0055). In the case of initially detected aneuploid myeloma cells, a contamination with malignant cells can be estimated with a simple flow cytometric method in PBSC harvests and in bone marrow after therapy.

Aneuploidy↗
PubMed1998

The incidence of DNA aneuploidy in multiple myeloma does not correlate with stage of disease.

The bone marrow of 47 patients with multiple myeloma (MM), 2 patients with plasma cell leukemia, and 11 patients with monoclonal gammopathy of undetermined significance (MGUS) was analyzed by flow cytometry for the detection of DNA aneuploidy. The question to be addressed was whether a correlation exists between the incidence of DNA aneuploidy and the stage of disease. With one-parameter analysis of DNA staining, a DNA aneuploidy was detectable in 17 of 60 patients. The detection rate for DNA aneuploidies could be increased to 37 of 60 patients with the second method, the simultaneous measurement of DNA content in additional immunophenotyped cells (CD38 or B-B4). In MGUS and the early stages of MM, the discrepancy between both methods was higher than in stage III MM. There were no statistical differences in the incidence of DNA aneuploidy between MGUS or the early stages of MM and stage III MM (21/32 patients vs 16/26 patients). The CD56 expression in plasma cells was significantly higher in cases of DNA aneuploidy (mean +/- SD, 64.7% +/- 33.65% vs 39.3% +/- 36.69%; P = .028). Comparing the ratio of diploid to DNA aneuploid with that of CD56+ to CD56- plasma cells, a correlation was found in MGUS (r = 0.7320) in the early stages of MM, I and II (r = 0.8023), but not in stage III MM. Based on these data, the dual-staining method for DNA content in immunophenotyped cells is preferred for the detection of DNA aneuploidy, especially in the early stages of MM and in MGUS. The clinical importance of a classification of DNA aneuploidy and CD56 antigen expression together is proposed for testing.

ADP-ribosyl Cyclase↗
PubMed1996

Complex cytogenetic and immunophenotypic aberrations in a patient with Sezary syndrome.

Sezary syndrome is defined as the leukemic variation of cutaneous T-cell lymphomas. Here we describe the cytogenetic pattern of peripheral T-cells of a 50-year-old male patient suffering from this disease. We used Giemsa-banding (G-banding) technique and a fluorescence in situ hybridization (FISH) assay to determine cytogenetic changes affecting 15 different chromosomes. The cells displayed an abnormal hypodiploid karyotype with a prominent insertion located at the short arm of chromosome 1. Unbalanced translocations were observed involving chromosomes 4 and 14. Besides other abnormalities we detected a 6q- deletion. These multiple genetic changes may reflect the high aggressivity of the neoplastically transformed T-cell population and the poor response to chemotherapeutic treatment.

Aneuploidy↗
PubMed1994

Detection of aneuploid cells in acute lymphoblastic leukemia with flow cytometry before and after therapy.

We have evaluated the proliferative activity and DNA content of immunophenotyped hematopoietic cells applying flow cytometry. After indirect immunofluorescence the cell membrane was permeabilized for propidium iodide staining of DNA. Compared with single parameter detection of DNA content this method has more certainty in the determination of aneuploidies in lymphatic leukemia cells. Immunophenotyped residual normal hematopoietic cells were used as an internal standard. If this method was tested for evaluation of therapeutic effects after chemotherapy greater sensitivity in detection of minimal residual disease was observed than when using microscopic evaluation or single parameter DNA analysis in cases of aneuploid lymphoblastic leukemias.

Aneuploidy↗