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K Lechner

Publications and source records attributed to K Lechner.

At least 127 records · Page 7Linked to original sources
PubMed1996

A case of malignant mastocytosis with circulating mast cell precursors: biologic and phenotypic characterization of the malignant clone.

The phenotypic and biologic properties of malignant cells in a case of aggressive mastocytosis with multi-organ involvement, circulating mast cell precursors and absence of skin infiltrates were analyzed. Circulating mast cell precursors were detected by immunostaining using antibodies against mast cell tryptase as well as by electron microscopy. These progenitors were tryptase+/chymase- (MCT) and accounted for 10 to 20% of nucleated mononuclear blood cells (MNC). A subset of them contained metachromatic granules. As assessed by combined toluidine blue/immunofluorescence staining, the granulated mast cell precursors were found to express CD9 (P24), CD33 (gp67) and CD44 (Pgp-1), but not basophil-related markers (CD11b (C3biR), CDw17 (lactosylceramide), CD123 (il-3R alpha))or monocyte-related antigens (CD14, CD15). Expression of the mast cell growth factor (MGF) receptor, c-kit(CD117), was also demonstrable, whereas the skin mast cell marker C5aR (CD88) could not be detected on mast cell precursors. The ligand of c-kit, recombinant human (rh) stem cell factor (SCF = MGF), induced histamine release from circulating mast cell progenitors, whereas rhC5a, a potent skin mast cell-/basophil-agonist, was ineffective over the dose-range (10(-9) to 10(-7(M)) tested. Analysis of mast cell antigens in malignant mastocytosis or mast cell leukemias may be helpful to establish a diagnosis and to determine the phenotype of the clone.

Adult↗
PubMed1996

Lupus anticoagulant and thromboembolism: evaluation of fibrinogen, natural inhibitors and molecular markers of thrombosis.

It has been speculated that an impairment in anticoagulant pathways (protein C (PC), protein S (PS), resistance to activated protein C (APC)), may contribute to the thrombotic tendency in lupus anticoagulant (LA) patients. Increased plasma levels of fibrinogen are predictive for arterial thrombosis and increased molecular markers of thrombosis are indicative for activation of the clotting cascade. We investigated 25 patients (20 women) with LA. All patients were stratified according to their thromboembolic history and women according to their history of fetal loss. Eighteen patients had a history of venous or arterial thrombosis, or both. Seven of 16 women with at least one pregnancy had a history of fetal loss. The interrelation among the levels of fibrinogen, PC and PS, and resistance to APC, thrombin-antithrombin III complexes (TAT), prothrombin fragment F1 + 2, D-dimer and the history of thrombotic events and obstetric complications in patients with LA were evaluated. LA patients with a history of venous or arterial thrombosis had a significantly higher fibrinogen level than LA patients without (mean 366 versus 304 mg/dl; P = 0.018). Among 16 women a slightly lower mean TAT level in women with fetal loss was found (2.4 versus 4.3 ng/ml; P = 0.02). No other statistically significant difference in the remaining parameters was yielded in both analyzed subgroups. The results of the study suggest an association between increased fibrinogen levels and the history of venous or arterial thrombosis, or both, in patients with LA. In the other investigated parameters, no relationship to the thrombotic or obstetric history was found.

Adult↗
PubMed1996

Probability of recurrence of thrombosis in patients with and without factor V Leiden.

Activated protein C (APC) resistance is a common risk factor for venous thromboembolism and is associated with the replacement of Arg 506 by Gln in the factor V gene (factor V Leiden). We investigated the risk of recurrence of venous thromboembolism in APC resistant patients heterozygous for FV Leiden and compared these patient groups with a group of patients, who had a history of venous thromboembolism, but had neither APC resistance nor the FV Leiden mutation. APC resistance was determined in frozen blood samples from patients with a history of venous thromboembolism, who were not receiving oral anticoagulant (OAC) treatment. The plasma samples were collected between 1984 and 1991. Twenty-one patients in whom APC resistance was found in the stored plasma samples were reinvestigated in 1994 (5 males, 16 females, median [m] age 49 years, range 21-71 years). Twenty-one sex and age matched patients with venous thromboembolism (5 males, 16 females, age m = 50 years, range 25-73 years) investigated during the same time period who had a normal APC resistance test served as a control group. Patients with APC resistance as well as controls were reinvestigated for the presence of FV Leiden by genetic analysis in 1994. Of the 21 APC resistant patients, 5 were homozygous and 16 heterozygous for FV Leiden. Before the study entry homozygous patients had a significantly higher recurrence rate (5/5 patients) compared to the control group in heterozygous patients (9/16) and controls (9/21) the recurrence rate was not significantly different. The total observation time was 21 years in patients with homozygous FV Leiden, 83 years in patients with heterozygous FV Leiden and 108 years in controls, excluding the time when patients were on OAC treatment. During the observation time the recurrence rate was highest in patients with homozygous FV Leiden (9.5% per patient per year), but was similar in patients with heterozygous FV Leiden (4.8% per patient per year) and controls (5% per patient per year). Two of five (40%) homozygous patients, 4/16 (25%) heterozygous and 5/21 (24%) controls had a least one recurrent event during the observation period. The probability for development of thrombosis in the Kaplan-Meyer-Plot analysis was not different between the three groups. Bearing limitations of our study in mind (retrospective design, relatively small patient number) we conclude that the risk of recurrence after a thromboembolic event is not higher in patients with heterozygous FV Leiden than in patients without this mutation. Thus, it appears that the identification of heterozygous FV Leiden mutation is not an indication for long-term OAC treatment. Also, long-term OAC treatment cannot generally be recommended for homozygous patients with a single thromboembolic event. More definitive conclusions will require larger prospective studies.

Adult↗
PubMed1996

G-CSF stimulation of donor myelopoiesis prolongs survival of relapsed BCR-ABL-positive acute lymphoblastic leukemia after allogeneic marrow transplantation.

An allogeneic sex-mismatched BMT which was performed in a male patient with BCR-ABL-positive ALL in second hematological and central nervous system relapse resulted in a CR for 12 months. After BMT, the patient was closely monitored with reverse transcription (RT)-PCR. One month before a third relapse RT-PCR became positive. During relapse G-CSF was administered. It specifically stimulated the donor-derived myelopoiesis and led to the stabilization of the disease for 8 months. Fluorescence in situ hybridization analyses of individual cell populations revealed that during the whole course of G-CSF administration granulocytes, CD4+, CD8+ and CD34+/CD10- cells were of female (donor) origin and only the CD34+/CD10+ cells which represented the leukemic blasts, were of male (host) origin.

Adult↗
PubMed1996

Stem cell factor-induced downregulation of c-kit in human lung mast cells and HMC-1 mast cells.

Recent data suggest that local overexpression of the tissue-hormone c-kit ligand (stem cell factor [SCF]) is associated with accumulation of mast cells (MCs) and a decrease in expression of c-kit in the accumulated MCs [28]. In the present study, the effects of recombinant human (rh) SCF on expression of c-kit mRNA and c-kit protein in isolated human MCs and a human mast cell line, HMC-1, were analyzed. Incubation of isolated lung MC with rhSCF (100 ng/mL) for 120 minutes resulted in decreased expression of c-kit mRNA (optical density [OD], control: 100% vs. rhSCF: 37%). Almost identical results were obtained with HMC-1 cells (OD, control: 100% vs. rhSCF: 40 to 45%). As assessed by flow cytometry and monoclonal antibodies (mAbs) to c-kit, the SCF-induced decrease of c-kit mRNA in HMC-1 was associated with a substantial decrease in surface expression of c-kit (MFI, control: 100 +/- 21%, vs. MFI in cells incubated with rhSCF [100 ng/mL at 37 degrees C for 12 hours]: 8 +/- 2%, vs. MFI in cells incubated with rhSCF, 100 ng/mL, at 4 degrees C: 34 +/- 3%). The effects of rhSCF on c-kit expression in HMC-1 cells were dose- and time-dependent with maximum effects observed with 10-100 ng/mL of rhSCF after 4 to 12 hours. The SCF-dependent loss of c-kit was also accompanied by a decreased chemotactic response to rhSCF (control: 100%; rhSCF: 71 +/- 2%). This study shows that exposure of human lung MC and HMC-1 cells to recombinant SCF results in downregulation of c-kit mRNA and surface c-kit expression. These data may explain the partial loss of c-kit on MCs in areas of SCF overexpression.

Blotting, Northern↗
PubMed1996

[Clinical use of polymerase chain reaction in diagnosis and monitoring of malignant diseases].

The polymerase chain reaction (PCR) has revolutionized the diagnosis of leukemias, lymphomas and solid tumors over the past 10 years. This molecular method can amplify tumorspecific DNA or RNA markers by a factor of up to 1 x 10(6). Clinical applications include: (1) improvement of histologic diagnosis through the detection of clonality and definition of molecular markers specifically associated with certain disease; (2) prognostic assessment at diagnosis, with impact on initial therapeutic decisions; (3) monitoring of minimal residual disease and early detection of impending relapse after chemotherapy or bone marrow transplantation; (4) detection of residual tumor cells in bone marrow and peripheral blood stem cell harvests; (5) diagnosis of hereditary tumor syndromes. A number of these PCR assays is already incorporated in routine laboratory diagnostic procedures, especially in acute and chronic leukemias. The final goal of the clinical application of PCR is the development of risk adapted therapeutic concepts for neoplastic disease.

Biomarkers, Tumor↗
PubMed1995

Increase of bcr-abl chimeric mRNA expression in tumor cells of patients with chronic myeloid leukemia precedes disease progression.

The translocation t(9;22) in chronic myeloid leukemia (CML) generates a bcr-abl fusion gene that codes for an aberrant chimeric mRNA. Cell lines established from CML patients in blast crisis show higher expression of this aberrant bcr-abl transcript than cells from patients in chronic phase of the disease. This observation provided the stimulus to investigate whether increased expression of the aberrant bcr-abl fusion transcript is critical to the progression of CML from chronic phase to blast crisis. We have monitored the bcr-abl mRNA expression in 25 patients by serial quantitative polymerase chain reaction analyses during a follow-up period of 12 to 156 months after diagnosis, with a median observation time of 28 months. In all patients who have shown disease progression to accelerated phase (n = 4) or blast crisis (n = 7), an increase in bcr-abl mRNA expression was detected up to 16 months before laboratory or clinical parameters showed phenotypic transformation of the malignant clone. To investigate whether the elevated levels of bcr-abl mRNA reflected an increase in the proportion of leukemic cells in the samples analyzed or primarily enhanced transcriptional activity of the bcr-abl fusion gene, we performed quantitative analyses of the bcr-abl gene at the DNA level and of the Ph chromosome at the cytogenetic level and compared these data with steady-state bcr-abl mRNA levels. We show that increased levels of the bcr-abl transcript did not reflect increased proportions of leukemic cells but elevated steady-state levels of the chimeric mRNA in the malignant cells before disease progression. Therefore, our data strongly suggest that an increase of the chimeric mRNA expression in the leukemic cells precedes the phenotypic transformation of the malignant clone.

Adult↗
PubMed1995

Differential expression of complement receptors on human basophils and mast cells. Evidence for mast cell heterogeneity and CD88/C5aR expression on skin mast cells.

Complement-dependent activation of immune cells is regulated by cell surface membrane receptors. In this study, expression of complement receptors (CR) on human blood basophils (n = 11), tissue mast cells (lung, n = 7; skin, n = 10; uterus, n = 4; tonsil, n = 3; heart, n = 10), and on respective human cell lines (basophil line KU-812, mast cell line HMC-1) was analyzed by the use of mAbs and indirect immunofluorescence. Normal blood basophils and KU-812 cells were found to express C5aR (CD88), membrane cofactor protein (CD46), decay-accelerating factor (CD55), and membrane attack complex inhibitory factor (CD59), as well as the previously recognized CR1 (CD35), CR3 alpha (CD11b), CR4 alpha (CD11c), and CR3/4 beta (CD18). Mast cells from all organs as well as HMC-1 cells expressed CD46, CD55, and CD59, but not CD11b, CD21, or CD35. The C5aR (CD88) was detectable on skin mast cells, a subset (5 to 15%) of cardiac mast cells, and on HMC-1 cells, but not on lung, uterus, or tonsillar mast cells (< 5%). Moreover, double immunoperoxidase staining (tryptase vs C5aR/CD88) revealed in situ expression of C5aR on skin, but not lung mast cells. Recombinant human (rh) C5a, at 10(-10) to 10(-7) M, induced secretion of histamine from basophils (rhC5a, 10(-8) M: 53.4 +/- 3.1% vs control < 5%) and from skin mast cells (rhC5a, 10(-8) M: 25.8 +/- 16.1% vs control < 10% histamine release), but not from other mast cells (rhC5a or control: < 10%, p > 0.05). The rhC5a-induced secretion of histamine from basophils and skin mast cells was inhibited by S5/1, a blocking Ab against CD88 (basophils: 37.2% to 75.1%; skin mast cells: 39.2% to 83.9% inhibition, p < 0.05). Together, this study shows that a) basophils and mast cells express a different profile of complement receptors, b) C5a-dependent mediator release in skin mast cells and basophils is mediated via CD88, and c) mast cells constitute a heterogeneous lineage in terms of expression of the C5a binding site CD88.

Antigens, CD↗
PubMed1995

Purification of human basophils and mast cells by multistep separation technique and mAb to CDw17 and CD117/c-kit.

Basophils and mast cells represent distinct cell lineages within the hemopoietic system. Based on the unique cell surface antigen profile of both cells, we have established methods which allow the reproducible purification to homogeneity (> 99%) of normal human basophil granulocytes from the peripheral blood and of mast cells from human dispersed tissues. Basophils (n = 9) were purified by current counterflow elutriation followed by depletion of monocytes with CD14 mAb conjugated to magnetic beads, and subsequent cell sorting for CD217+ cells. Basophil purity was 99.5 +/- 0.4% (range 98.7-99.9%). Mast cells were obtained from lung (n = 6), uterus (n = 1), mastocytosis bone marrow (n = 2), and human foreskin (n = 2). Mast cells were purified by collagenase digestion followed by current counterflow elutriation and sorting with CD117/c-kit mAb. Mast cell purity was 99.4 +/- 0.7% (range: 97.5-99.9%). Purified cells were more than 90% viable and were able to release histamine on induction with IgE plus anti-IgE. Furthermore, the PCR technique could be applied on pure cells and confirmed expression of high affinity IgE receptor (Fc epsilon R1) alpha chain mRNA. Thus, by combining isolation techniques including elutriation, magnetic cell depletion and cell sorting with mAb, functionally intact normal human basophils and mast cells can be enriched to homogeneity.

Antibodies, Monoclonal↗
PubMed1995

Increase and redistribution of cardiac mast cells in auricular thrombosis. Possible role of kit ligand.

BACKGROUND: The atrial appendage is a predilection site for thrombus formation. Mast cells (MC) are a rich source of mediators that may be involved in the regulation of thrombus formation. We examined number, distribution, and phenotype of MC in thrombosed versus unaffected auricles to elucidate their possible role in auricular thrombosis (AUTHR). METHODS AND RESULTS: Sections of atrial appendages (AUTHR, n = 14; controls (CO), n = 13) were analyzed for MC by Giemsa, toluidine blue, and berberine sulfate stains and by immunohistochemistry. Cardiac MC expressed CD antigens corresponding to the classic MC phenotype as well as tryptase, chymase, and heparin. Thrombosis was associated with a twofold increase in the number of MC in the total appendage (CO, 3.1 +/- 1.0 versus AUTHR, 6.4 +/- 1.1 MC/mm2, P < .01). Moreover, in AUTHR, a redistribution of MC to the upper endocardium was observed (AUTHR, 5.3 +/- 1.4 versus CO, 0.07 +/- 0.15 MC/mm2, P < .01). Mast cell growth factor (MGF) was expressed in the endothelium and subendothelial space of thrombosed appendages but not in the normal endocardium. Overexpression of MGF was accompanied by a weak or absent expression of the MGF receptor c-kit on redistributed MC in AUTHR. Patients with unilateral atrial appendage thrombosis did not exhibit a MC increase or redistribution in the unaffected contralateral appendage. No augmentation of other inflammatory cells was observed. Stimulation of isolated cardiac MC with MGF resulted in mediator release. CONCLUSIONS: This study provides evidence that AUTHR is associated with MC increase and redistribution and MGF overexpression. The role of redistributed MC and their mediators in the pathophysiology of atrial thrombosis requires further investigation.

Adult↗
PubMed1995

Differential response of human basophils and mast cells to recombinant chemokines.

Chemokines are proinflammatory peptides regulating the functions of various hematopoietic cells. We have analyzed the effects of seven recombinant human (rh) chemokines (MCAF, RANTES, MIP-1 alpha, MIP-1 beta, IL-8, GRO, and IP-10) on the growth and function of human basophils and mast cells. We found that MCAF, but not RANTES, MIP-1 alpha, MIP-1 beta, IL-8, GRO, or IP-10, causes direct and dose-dependent histamine release from basophils (MCAF, 5 micrograms/ml: 26.9 +/- 3.4%; other chemokines: < 5% of total histamine). An increased (2.1 to 3.5-fold) response to MCAF was obtained when basophils were preincubated with rh interleukin-3 (100 units/ml). Moreover, IL-3-primed basophils became responsive to physiologic concentrations (< 1 microgram/ml) of MCAF, IL-8, and RANTES. None of the chemokines tested was able to induce histamine secretion in mast cells obtained from lung (n = 2), skin (n = 1), uterus (n = 3), or tonsils (n = 3), even when cells had been preincubated with the mast cell agonist SCF. The chemokines also failed to modulate the expression of activation antigens (CD11b/C3biR, CD25/IL-2R beta, CD63, IL-3R alpha, CD117/c-kit) on the mast cell line HMC-1 or the basophil cell line KU-812 and were unable to induce differentiation of basophils or mast cells in culture. Together, our results show that basophils respond to rhIL-8, rhMCAF, and rhRANTES and that, unlike human basophils, human mast cells are unresponsive to recombinant chemokines.

Antigens, CD↗
PubMed1995

Rapid elimination of a high-titer spontaneous factor V antibody by extracorporeal antibody-based immunoadsorption and immunosuppression.

We report on the rapid elimination of a potent spontaneous factor V antibody of undetermined etiology by extracorporeal immunoadsorption on sepharose-bound polyclonal sheep antibodies to human immunoglobulins (Ig-Therasorb, Baxter) in combination with immunosuppressive treatment. A 68-year-old woman presented with severe hematuria. Severe factor V deficiency (< 1%) caused by an antibody to factor V (26 BU/ml) was found. Extracorporeal immunoadsorption (8.245 +/- 553 ml plasma processed per session) led to an average reduction of the antibody titer by 75% per session. The procedure was well tolerated without any side effects. Hematuria ceased after three immunoadsorptions and complete elimination of the antibody was achieved after seven sessions (day 15), followed by a rapid increase of the factor V activity to normal levels. Treatment with cyclophosphamide and prednisone was started on day 6 and continued for 2 months. The patient remains in remission at 6 months. Extracorporeal immunoadsorption is a highly effective method for eliminating antibodies to factor V (or other clotting factors) in selected cases, i.e., in patients with severe bleeding tendency, high antibody titer, and low probability of a rapid spontaneous remission.

Aged↗
PubMed1995

Dexverapamil as resistance modifier in acute myeloid leukaemia.

In order to evaluate dexverapamil as a resistance modifier in acute myeloid leukaemia, we have added dexverapamil (4 x 300 mg/d orally) to DA chemotherapy (daunorubicin, cytosine arabinoside) in six patients with acute myeloid leukaemia. Two patients (1 first and 1 second relapse) achieved complete remission and two patients (1 refractory disease, 1 third relapse) showed some improvement. One patient in first relapse died due to disease progression and one drug-refractory patient remained refractory. The peak plasma levels of dexverapamil and nordexverapamil ranged from about 600 to 4100 ng/ml and from 450 to 1130 ng/ml, respectively. Major sideeffects were hypotension and sinus bradycardia. These results show the need for further evaluation of dexverapamil as a resistance modifier in acute myeloid leukaemia.

ATP Binding Cassette Transporter, Subfamily B, Mem↗