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Lothar Kanz

Publications and source records attributed to Lothar Kanz.

70 records · Page 4Linked to original sources
PubMed2003

Nonpeptide mediators in the hematopoietic microenvironment.

Migration of hematopoietic stem and progenitor cells (HPCs) is controlled by chemotactic factors released in the hematopoietic microenvironment. In particular, the chemokine SDF-1, which activates the G protein-coupled receptor (GPR) CXCR4, plays an important role in progenitor cell mobilization and homing. However, we provide evidence that ligands of other GPRs similarly act on CD34(+) hematopoietic progenitors. These ligands comprise non-peptide mediators, including the cysteinyl-leukotriene receptor CysLT1, and stimulate migration and integrin-dependent adhesion of HPCs. Moreover, continuous activation of a GPR by a specific ligand upregulates the responsiveness of other GPRs to their corresponding ligands. These findings suggest that HPC migration may not depend on a single chemokine receptor (e.g., CXCR4). Rather, mobilization and homing of HPCs involve several GPRs, which interact with each other as well as with adhesion molecules. Pharmacological activation and inhibition of the GPR may allow HPC mobilization and homing to be modulated.

Animals↗
PubMed2003

CDCP1 is a novel marker for hematopoietic stem cells.

CDCP1 is a transmembrane protein that contains three CUB domains within the extracellular region and a hexalysine stretch within the cytoplasmic region. CDCP1 mRNA is highly expressed in lung and colon tumors and in the erythroleukemic cell line K562. To analyze CDCP1 protein expression, monoclonal antibodies against the extracellular domain of CDCP1 were raised. For this purpose, CDCP1 was overexpressed in NIH-3T3 cells. Balb/c mice were then immunized with the resultant cell line NIH-3T3/huCDCP1. After fusion of SP2/0 cells with immune spleen cells, hybridoma clones were selected that secreted antibodies reacting with NIH-3T3/huCDCP1 cells but not with parental cells. Four antibodies (CUB1-CUB4) were obtained that fulfilled these criteria. Screening of peripheral blood cells revealed that the antibodies did not recognize mature lymphocytes, monocytes, granulocytes, erythrocytes, or platelets. In contrast, multi-color analyses revealed that CDCP1 protein is almost exclusively expressed on a subset of CD34(+) stem/progenitor cells in bone marrow. Transplantation of purified CDCP1(+) cells into NOD/SCID mice resulted in engraftment of human cells with multi-lineage differentiation potential, suggesting that CDCP1 is a novel marker for hematopoietic stem cells.

3T3 Cells↗
PubMed2003

Antibody W7C5 defines a CD109 epitope expressed on CD34+ and CD34- hematopoietic and mesenchymal stem cell subsets.

The cell surface antigen recognized by monoclonal antibody W7C5 is expressed at low levels on human CD34(+) and CD34(-) bone marrow stem cell populations but at high levels on fetal liver CD34(+) cells. To identify the recognized antigen, we performed partial amino acid sequence and MALDI analysis of purified W7C5 antigens. The analyses revealed that MoAb W7C5 detects CD109, a recently cloned glycophosphatidylinositol-linked glycoprotein. The specificity of MoAb W7C5 was further confirmed by the selective recognition of CHO cells transfected with human CD109 cDNA.

Amino Acid Sequence↗
PubMed2003

Heterogeneity among human bone marrow-derived mesenchymal stem cells and neural progenitor cells.

BACKGROUND AND OBJECTIVES: Mesenchymal stem cells (MSC) and neural progenitor cells (NPC) are pluripotent cells. The former can give rise to myocytes, chondrocytes, adipocytes, and osteogenic cells, while the latter can give rise to astrocytes, neurons, and oligodendrocytes. The aim of this study was to analyze and compare the antigen expression patterns of MSC and NPC. DESIGN AND METHODS: Human bone marrow-derived MSC and NPC were analyzed by flow cytometry and immunocytochemistry using a variety of unique monoclonal antibodies (57D2, W4A5, W8B2) generated in our laboratory. In addition, the expression profile of CD antigens and intracellular differentiation markers was analyzed. RESULTS: We show for the first time that CD10+, CD13+, CD61+, CD90+, CD105 (endoglin)+, CD45-, CD34-, and CD133- MSC also expressed CD109, CD140b (PDGF-RB), CD164, and CD172a (SIRPa). In addition, we found heterogeneity of MSC as demonstrated by the preferential expression of nestin and W8B2 antigen on distinct MSC subpopulations. Morphologically, these populations comprised small single cells and larger cells with polygonal appearance. NPC expressed high levels of CD56, CD90 and nestin and moderate levels of CD15, W4A5, and 57D2 antigens. In contrast, CD133 and CD172 were found only on NPC subpopulations. INTERPRETATION AND CONCLUSIONS: Our data demonstrate nestin expression in most NPC as well as in immature MSC subpopulations. MSC and NPC subpopulations can now be distinguished using our novel antibodies W8B2, 57D2, and W4A5.

Antigens, CD↗
PubMed2003

Idiotype vaccination of multiple myeloma patients using monocyte-derived dendritic cells.

BACKGROUND AND OBJECTIVES: Dendritic cells (DC) pulsed with multiple myeloma (MM) patient-specific idiotype (Id) protein can induce MM-specific T-cell responses. DESIGN AND METHODS: We established serum-free culture conditions to generate monocyte-derived DC for clinical use to circumvent anti-xenogenic immune responses with repetitive vaccinations. In a clinical phase I trial twelve patients responsive to high dose chemotherapy (HDT) were vaccinated with autologous Id pulsed DC vaccines followed by Id/keyhole limpet hemocyanin (Id/KLH) booster immunizations co-injected with granulocyte-macrophage colony-stimulating factor as adjuvant. RESULTS: In vitro studies showed that serum-free-generated DC were equally effective in the induction of specific T-cell responses as were DC generated with fetal calf serum. On average 4.5 x 10(6) DC of >60% purity were generated from peripheral blood monocytes obtained 3-6 months after HDT and autologous stem cell transplantation. Ten of twelve patients received all planned vaccines without serious toxicity. Two patients developed Id-specific T-cell proliferative responses, in one patient an Id-specific cytotoxic T lymphocyte (CTL) response was measured. Id-specific TH1 cytokine secretion was found in one of the T-cell responding patients. All patients who received at least three Id/KLH vaccines mounted strong KLH specific T-cell and delayed antibody responses. Two patients remain in clinical partial response at 25 and 29 months after the start of the vaccination and ten patients have progressed, six of whom have died from progressive disease or infectious complications. INTERPRETATION AND CONCLUSIONS: Serum-free DC vaccines induce Id-specific T-cell responses in MM patients.

Adjuvants, Immunologic↗
PubMed2002

Infusion of cytomegalovirus (CMV)-specific T cells for the treatment of CMV infection not responding to antiviral chemotherapy.

We adoptively transferred donor-derived cytomegalovirus (CMV)-specific T-cell lines into 8 stem cell transplant recipients lacking CMV-specific T-cell proliferation. All patients, of whom one was infected by a CMV strain that was genotypically ganciclovir resistant, had received unsuccessful antiviral chemotherapy for more than 4 weeks. CMV-specific lines had been prepared by repetitive stimulation with CMV antigen, which increased the percentage of CMV-specific T cells and ablated alloreactivity completely even against patients mismatched for 1 to 3 HLA antigens. After transfer of 10(7) T cells/m(2) at a median of 120 days (range, 79-479 days) after transplantation, no side effects were noticed. Despite cessation of antiviral chemotherapy, the CMV load dropped significantly in all 7 evaluable patients, with a maximal reduction after a median of 20 days (range, 5-31 days). In 2 patients with high virus load, the antiviral effect was only transient. One of these patients received a second T-cell infusion, which cleared the virus completely. At a median of 11 days after transfer, CMV-specific T-cell proliferation was demonstrated in 6 patients, and an increase in CMV-specific CD4(+) T cells was demonstrated in 5 patients. In 6 patients, 1.12 to 41 CMV-specific CD8(+) T cells/microL blood were detected at a median of 13 days after transfer, with an increase in all patients lacking CMV-specific CD8(+) T cells prior to transfer. Hence, anti-CMV cellular therapy was successful in 5 of 7 patients, whereas in 2 of 7 patients, who received an intensified immune suppression at the time of or after T-cell therapy, only transient reductions in virus load were obtained.

Adoptive Transfer↗
PubMed2002

Sensitive detection of human cytomegalovirus peptide-specific cytotoxic T-lymphocyte responses by interferon-gamma-enzyme-linked immunospot assay and flow cytometry in healthy individuals and in patients after allogeneic stem cell transplantation.

Reconstitution of human cytomegalovirus (HCMV)-specific cytotoxic T lymphocytes (CTLs), predominantly directed against pp65, provides protective immunity for the development of HCMV disease after allogeneic stem cell transplantation (SCT). To define pp65-derived CTL epitopes that would allow sensitive detection of HCMV-specific immune reconstitution, a computer-based epitope prediction was performed. Peptide-specific CTL responses were assessed by interferon-gamma release. With this approach, pp65-derived epitopes presented by the HLA alleles A*0101, A*0201, A*1101, and B*0702 were identified. The frequency of CTLs in healthy HCMV-seropositive individuals ranged from about 0.1% to 3.3% of all CD8(+) T cells. In patients at risk of HCMV infection after allogeneic SCT, HCMV-peptide-specific CTLs were found in 14 of 19 patients at a median of 90 days after SCT (range, 35-234 days) and HCMV-antigen-specific CD4(+) T lymphocytes in 11 of 18 patients at a median of 90 days after SCT (range, 35->180 days). Peak counts of peptide-specific CD8(+) T cells ranged from 0.14 to 60.6 cells/microL; those of protein-specific CD4(+) T cells ranged from 0.64 to 18.97 cells/microL. Reconstitution of HCMV-peptide-specific CD8(+) T cells and protein-specific CD4(+) T cells was associated with clearance of HCMV infection (r(2) = 0.89, P <.0001 and r(2) = 0.61, P =.0045, respectively). HCMV infection recurred after documentation of HCMV-specific T-cell reconstitution (n = 4) when immunosuppression was intensified. Patients in whom late-onset HCMV disease developed lacked HCMV-protein-specific T cells at 3 months after SCT. In conclusion, prospective monitoring of HCMV-specific CD4(+) and CD8(+) T-cell reconstitution can be performed rapidly by using flow cytometry after specific stimulation with HCMV peptides and proteins and might help to further improve clinical management of HCMV infection after allogeneic SCT.

Adult↗
PubMed2002

Prospective comparison of [18F]fluorodeoxyglucose positron emission tomography with conventional assessment by computed tomography scans and serum tumor markers for the evaluation of residual masses in patients with nonseminomatous germ cell carcinoma.

BACKGROUND: To assess the ability of [(18)F]fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) to predict the viability of residual masses after chemotherapy in patients with metastatic nonseminomatous germ cell tumors (GCT), PET results were compared in a blinded analysis with computed tomography (CT) scans and serum tumor marker changes (TUM) as established methods of assessment. METHODS: Independent reviewers who were blinded to each other's results evaluated the PET results and corresponding CT scan and TUM results in 85 residual lesions from 45 patients. All patients were treated within prospective clinical trials and received primary/salvage, high-dose chemotherapy with autologous blood stem cell support for primary poor prognosis disease or recurrent disease. PET results were assessed both visually and by quantifying glucose uptake (standardized uptake values). Results were validated either by histologic examination of a resected mass and/or biopsy (n = 28 lesions) or by a 6-month clinical follow-up after evaluation (n = 57 lesions). RESULTS: F-18 FDG PET showed increased tracer uptake in 32 of 85 residual lesions, with 29 true positive (TP) lesions and three false positive (FP) lesions. Fifty-three lesions were classified by PET as negative (no viable GCT), 33 lesions were classified by PET as true negative (TN), and 20 lesions were classified by PET as false negative (FN). In the blinded reading of the corresponding CT scan and TUM results, 38 residual lesions were assessed correctly as containing viable carcinoma and/or teratoma. Forty-six lesions were classified as non-suspicious by CT scan/TUM (33 TN lesions and 14 falsely classified lesions). PET correctly predicted the presence of viable carcinoma in 5 of these 14 and the absence of viable carcinoma in 3 of these 14 lesions. Resulting sensitivities and specificities for the prediction of residual mass viability were as follows: PET, 59% sensitivity and 92% specificity; radiologic monitoring, 55% sensitivity and 86% specificity; and TUM, 42% sensitivity and 100% specificity. The positive and negative predictive values for PET were 91% and 62%, respectively. The diagnostic efficacy of PET did not improve when patients with teratomatous elements in the primary tumor were excluded from the analysis. In patients with multiple residual masses, a uniformly increased residual F-18 FDG uptake in all lesions was a strong predictor for the presence of viable carcinoma. CONCLUSIONS: F-18 FDG PET imaging performed in conjunction with conventional staging methods offers additional information for the prediction of residual mass histology in patients with nonseminomatous GCT. A positive PET is highly predictive for the presence of viable carcinoma. Other useful indications for a PET examination include patients with multiple residual masses and patients with marker negative disease.

Adult↗
PubMed2002

Extragonadal germ cell tumors of the mediastinum and retroperitoneum: results from an international analysis.

PURPOSE: To characterize the clinical and biologic features of extragonadal germ cell tumor (EGCT) and to determine the overall outcome with currently available treatment strategies. PATIENTS AND METHODS: Of an unselected population of 635 consecutive patients treated from 1975 through 1996 at 11 cancer centers, 341 patients (54%) had primary mediastinal EGCT, and 283 patients (45%) had retroperitoneal EGCT. Five hundred twenty-four patients (83%) had a nonseminomatous germ cell tumor (GCT), and 104 patients (16%) had a seminomatous histology. RESULTS: After platinum-based induction chemotherapy with or without secondary surgery, 141 patients (49%) with mediastinal nonseminomas (median follow-up, 19 months; range, 1 to 178 months) and 144 patients (63%) with retroperitoneal nonseminoma (median follow-up, 29 months; range, 1 to 203 months) are alive (P =.0006). In contrast, the overall survival rate for patients with a seminomatous EGCT is 88%, with no difference between patients with mediastinal or retroperitoneal tumor location (median follow-up, 49 months; range, 4 to 193 months; respective 70 months; range, 1 to 211 months). A significantly lower progression-free survival rate was found in seminoma patients treated with initial radiotherapy alone compared with chemotherapy. Nonseminomatous histology, presence of nonpulmonary visceral metastases, primary mediastinal GCT location, and elevated beta-human chorionic gonadotropin were independent prognostic factors for shorter survival. Hematologic malignancies (n = 17) occurred without exception in patients with primary mediastinal nonseminoma. Sixteen patients developed a metachronous testicular cancer despite the use of platinum-based chemotherapy. CONCLUSION: Whereas patients with pure seminomatous EGCT histology have a long-term chance of cure of almost 90% irrespective of the primary tumor site, 45% of patients with mediastinal nonseminomas are alive at 5 years. This outcome is clearly inferior compared with patients with nonseminomatous retroperitoneal primary tumors.

Adolescent↗
PubMed2002

Sustained remission of an extensive monoclonal, Epstein-Barr virus-associated diffuse large B cell lymphoma in a kidney-pancreas transplant recipient.

BACKGROUND: Epstein-Barr virus associated posttransplant high-grade large cell lymphoma (EBV-PTL) is thought to be incurable solely by cessation of immunosuppression. We report a case of EBV-PTL resolving rapidly after alleviation of immunosuppression. A strong cytotoxic memory T cell (CTL) reaction against two individual recipient EBV strains appears to be involved. METHODS: EBV strain identification in donor lymphocytes, tumor cells of EBV-PTL, and circulating lymphocytes of recipient was performed by latent membrane protein 1 fingerprinting. RESULTS: Stage IIIB EBV-PTL of recipient type was cured through strong autologous CTL reaction consecutive to alleviation of immunosuppression. Latent membrane protein 1 fingerprinting identified three different EBV strains; namely in lymphoma and peripheral lymphocytes of donor and recipient. CONCLUSION: In the setting of solid organ transplantation, rigorous reduction of immunosuppression may lead to cure of high grade EBV-PTL, if the recipient delivers a strong host CTL reaction against the epitopes of EBV latency gene products. Infection with two individual EBV strains earlier in life may increase the number of specific CTL clones and increase the memory capacity.

Adult↗
PubMed2002

German Cancer Society Neuro-Oncology Working Group NOA-03 multicenter trial of single-agent high-dose methotrexate for primary central nervous system lymphoma.

The prospective multicenter NOA-03 trial, conducted by the Neuro-Oncology Working Group (NOA) of the German Cancer Society, was initiated to define the feasibility and efficacy of single-agent high-dose methotrexate therapy without concomitant radiotherapy in immunocompetent patients with primary central nervous system lymphoma. Thirty-seven patients (median age, 60 years) received 179 biweekly courses of 8 g/m2 methotrexate. Response was assessed after 3 and 6 courses. We had planned to enter 105 patients into the trial. Since fewer than the projected 18 of 37 patients achieved a complete response after an intermediate analysis, the trial was closed. In intention-to-treat analysis, 11 of 37 patients (29.7%) achieved complete response, whereas 14 of 37 patients (37.8%) were found to have progressive disease. The median relapse-free survival among complete response patients was 13.7 months. Multivariate logistic regression analysis revealed that corticosteroid application during the first methotrexate course was associated with complete response. The regimen was well tolerated, but, unlike previously reported results, the activity of high-dose methotrexate was only moderate.

Adult↗
PubMed2002

Human plasma thrombopoietin levels are regulated by binding to platelet thrombopoietin receptors in vivo.

BACKGROUND: Data from several studies support the hypothesis that thrombopoietin (TPO) plasma levels are regulated via circulating platelet (PLT) numbers by binding to PLT TPO receptors (TPO-Rs). In this study, PLT numbers and TPO plasma levels were measured following the transfusion of unmanipulated, sham-saturated, and TPO-R-saturated PLT preparations to provide additional in vivo evidence for this regulatory mechanism. STUDY DESIGN AND METHODS: Following in vitro experiments to characterize pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) binding characteristics, PLT numbers and TPO plasma levels were measured following the transfusion of unmanipulated, sham-saturated, and TPO-R-saturated PLT preparations in thrombocytopenic patients. Sham-saturated and TPO-R-saturated PLTs were prepared by a 1-hour incubation without and with 40 ng per mL of PEG-rHuMGDF, respectively, and subsequent washing and resuspension. RESULTS: In vitro, 2.72 +/- 0.8 ng of PEG-rHuMGDF per 1 x 10(8) PLTs was bound within 1 hour of incubation. No additional PEG-rHuMGDF was bound following a second incubation with PEG-rHuMGDF, and bound PEG-rHuMGDF was not released over time. In vivo, TPO plasma levels decreased significantly (p < 0.001), by 30.7 +/- 5.8 and 20.9 +/- 2.1 percent after transfusion of unmanipulated and sham-saturated PLT preparations, respectively. However, TPO plasma levels were unaffected after the transfusion of TPO-R-saturated PLTs despite comparable transfusion-induced PLT count increases. CONCLUSION: These data strongly support the concept that binding to PLT TPO-R is directly involved in human TPO plasma level regulation in vivo.

Blood Platelets↗
PubMed2002

Enhanced erythrocyte apoptosis in sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency.

Erythrocyte diseases such as sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency decrease the erythrocyte life span, an effect contributing to anemia. Most recently, erythro-cytes have been shown to undergo apoptosis upon increase of cytosolic Ca(2+) activity. The present study has been performed to explore whether sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency enhance the sensitivity of erythrocytes to osmotic shock, oxidative stress or energy depletion, all maneuvers known to increase cytosolic Ca(2+) activity. To this end, annexin binding as an indicator of apoptosis has been determined by FACS analysis. Erythrocytes from healthy individuals, from patients with sickle cell anemia, thalassemia or glucose-6-phosphate dehydrogenase deficiency all responded to osmotic shock (up to 950 mOsm by addition of sucrose for 24 hours), to oxidative stress (up to 1.0 mM tetra-butyl-hydroxyperoxide tBOOH) and to energy depletion (up to 48 hours glucose deprivation) with enhanced annexin binding. However, the sensitivity of sickle cells and of glucose-6-phosphate dehydrogenase deficient cells to osmotic shock and of sickle cells, thalassemic cells and glucose-6-phosphate dehydrogenase deficient cells to oxidative stress and to glucose depletion was significantly higher than that of control cells. Annexin binding was further stimulated by Ca(2+) ionophore ionomycin with significantly higher sensitivity of sickle cells and glucose-6-phosphate dehydrogenase deficient cells as compared to intact cells. In conclusion, sickle cells, thalassemic cells and glucose-6-phosphate dehydrogenase deficient erythrocytes are more sensitive to osmotic shock, oxidative stress and/or energy depletion, thus leading to enhanced apoptosis of those cells. The accelerated apoptosis then contributes to the shortened life span of the defective erythrocytes.

Analysis of Variance↗
PubMed2000

Molecular methods in the diagnosis of infections in the immunocompromised host.

Despite recent developments, infection remains a major obstacle to a successful outcome in transplantation. Molecular methods have allowed for earlier diagnosis and have proven to be powerful tools for analysing the epidemiology of infectious diseases. More recently, some of these molecular methods have been commercialized, enabling standardized diagnostic techniques to be used in multicentre trials.

Journal Article↗
PubMed2000

CMV Infection in Bone Marrow and Solid Organ Transplant Patients in the Era of Antiviral Prophylaxis.

Recent developments in the diagnosis and therapy of cytomegalovirus (CMV) infection have helped to reduce CMV-associated morbidity and mortality following allogeneic bone marrow and solid organ transplantation. The clinical symptoms of active CMV infection and the prevalence of life-threatening CMV disease vary widely between different patient populations according to the type of transplant and the intensity of immunosuppression employed. Antiviral prophylaxis with aciclovir, valaciclovir and ganciclovir has been shown to reduce CMV infection and disease following organ transplantation. Antiviral drugs, in particular ganciclovir and foscarnet, have varying sideeffects, however, and antiviral resistance due to prolonged administration of ganciclovir and foscarnet has been reported recently. Short courses of pre-emptive antiviral therapy for documented CMV infection help to reduce the duration and sideeffects of therapy, offering an alternative strategy to antiviral prophylaxis. Studies are required to compare the efficacy and costs of antiviral prophylaxis with pre-emptive therapy.

Journal Article↗