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B Van Camp

Publications and source records attributed to B Van Camp.

At least 37 records · Page 2Linked to original sources
PubMed2000

In vivo induction of insulin-like growth factor-I receptor and CD44v6 confers homing and adhesion to murine multiple myeloma cells.

One of the main characteristics of multiple myeloma (MM) cells is their specific homing and growth in the bone marrow (BM). Differences between stroma-dependent and -independent MM cell lines may reveal key molecules that play important roles in their homing to the BM. We addressed this topic with a murine MM model, including the in vivo 5T33MM (5T33MMvv) stroma-dependent cell line and its in vitro stroma-independent variant (5T33MMvt). Fluorescence-activated cell-sorting analysis showed expression of insulin-like growth factor (IGF)-I receptor and CD44v6 on all 5T33MMvv cells but not on 5T33MMvt cells. Checkerboard analysis and adhesion assays revealed IGF-I-dependent chemotaxis toward BM-conditioned medium and involvement of CD44v6 in the adhesion to BM stroma of only 5T33MMvv cells. However, when 5T33MMvt cells were injected in vivo (5T33MMvt-vv), after 18 h the MM cells harvested from BM were IGF-I receptor and CD44v6 positive. This up-regulation was confirmed in 5T33MMvt-vv cells isolated from terminally diseased animals. These ST33MMvt-vv cells exhibited IGF-I-dependent chemotaxis and CD44v6-dependent adhesion to BM stroma. In vitro culture of the 5T33MMvt-vv cells could completely down-regulate IGF-I receptor and CD44v6. In fact, we could show that direct contact of 5T33MMvt cells with BM endothelial cells is a prerequisite for IGF-I receptor and CD44v6 up-regulation. These data indicate that the BM microenvironment is capable of up-regulating molecules such as IGF-I receptor and CD44v6, which facilitate homing of MM cells to the BM and support their adhesion to BM stroma.

Amino Acid Sequence↗
PubMed2000

The clinical impact of early gram-positive bacteremia and the use of vancomycin after allogeneic bone marrow transplantation.

BACKGROUND: Gram-positive bacteremia (GPB) is an increasing infection after allogeneic bone marrow transplantation (BMT). Our purpose was to identify risk factors for GPB, to evaluate its impact on early mortality and morbidity, and to compare prophylactic with empirical intravenous vancomycin. METHODS AND RESULTS: We studied 89 consecutive BMTs in adult patients. Early GPB occurred in 29% of posttransplantation episodes. T-cell depletion (odds ratio [OR]: 0.18) and vancomycin-prophylaxis (OR: 0.28) reduced the risk of GPB. Mortality at 6 weeks was not significantly different in patients with GPB (15% vs. 9.5%, P = 0.669). GPB was associated with the development of major complications, the use of amphotericin B, and prolonged neutropenia. Vancomycin prophylaxis led to an increased risk of early renal dysfunction (OR: 18.7). CONCLUSION: GPB contributes to overall morbidity during the early post-BMT episode but has no impact on mortality. Vancomycin prophylaxis is effective to reduce GPB but has a negative effect on renal function.

Adolescent↗
PubMed2000

Clonally related IgA- and IgE-secreting plasma cells in a myeloma patient.

OBJECTIVES: The purpose of this work was to study the clonal relationship between the cells that secrete monoclonal proteins in an IgA/ IgE double multiple myeloma patient. Double monoclonal gammopathy is a rare condition in which two types of monoclonal proteins can be found in the serum and/or urine of patients with multiple myeloma or gammopathy of undetermined significance. The study of the relationship between the cells expressing the different monoclonal proteins may provide insight in the pathogenesis of these disorders. METHODS: The clonal relationship of the two tumoral plasma cell populations was examined by immunophenotyping and sequence analysis of the variable regions of the immunoglobulin heavy chain genes. Both immunoglobulin sequences were isolated from the bone marrow using a polymerase chain reaction (PCR)-based cloning strategy. Rare isotype-switch variants were detected by a myeloma-specific PCR in combination with different isotype-specific primers. An in vitro culture system, based on the activation of the CD40 molecule on the B cell, was used in order to isolate and expand myeloma-related B cells from peripheral blood that could possibly be regarded as myeloma precursor cells. RESULTS: The variable parts of the immunoglobulin heavy chains linked to either Calpha or Cepsilon were exactly the same, including the same somatic mutations. From the in vitro CD40 cultures B cells could be isolated that either expressed IgA or IgE with exactly the same variable immunoglobulin part as the myeloma clone. No pre-switched IgM myeloma-related B cells could be found. CONCLUSION: Both cell populations in this IgA/IgE myeloma patient shared a common clonal origin. No evidence for a pre-switched IgM precursor myeloma cell was found in this patient.

Aged↗
PubMed2000

The potent bisphosphonate ibandronate does not induce myeloma cell apoptosis in a murine model of established multiple myeloma.

Bisphosphonates are effective in the management of bone disease in patients with multiple myeloma and recent reports have suggested that they may also have an anti-tumour activity. In support of this, we have previously demonstrated that bisphosphonates can induce myeloma cell apoptosis in vitro; however, it remains unclear whether this occurs in vivo. We have therefore investigated the effect of the potent bisphosphonate ibandronate in the 5T2MM murine model of established multiple myeloma. Short-term treatment with a high dose of ibandronate had no effect on either myeloma cell number or the proportion of myeloma cells undergoing apoptosis. These observations suggest that although bisphosphonates induce apoptosis in myeloma cells in vitro, they may not have the same anti-tumour effects in vivo.

Animals↗
PubMed2000

Bone sialoprotein mRNA and protein expression in human multiple myeloma cell lines and patients.

Bone sialoprotein (BSP) is a glycoprotein essentially found in mineralizing connective tissues. We have recently demonstrated that BSP is ectopically expressed by carcinomas that metastasize to bone with high frequency. Multiple myeloma (MM) is characterized by the localization of tumour plasma cells in the bone marrow. In this study, BSP expression was evaluated in human myeloma cell lines and in bone marrow aspirates and one ascites fluid from MM patients. BSP was detectable in conditioned media of MM cell lines. Using FACS analysis and in situ hybridization, we demonstrated that tumour cells from all MM patients and cell lines analysed express BSP at both the protein and the mRNA level.

Bone Marrow↗
PubMed2000

Selective initial in vivo homing pattern of 5T2 multiple myeloma cells in the C57BL/KalwRij mouse.

One of the main characteristics of multiple myeloma cells is their predominant localization in the bone marrow. It is, however, unclear whether this is due to a selective initial entry, or whether this entry is more random and other processes like survival and/or growth stimulation, only present in the medullar microenvironment, are unique. To investigate this, in vivo homing kinetics of murine 5T2MM cells shortly after injection were assessed in bone marrow, liver, spleen, lungs, heart, intestines, kidney and testis by tracing of radiolabelled cells, by immunostaining of isolated cells and by polymerase chain reaction analysis. We demonstrated the presence of 5T2MM cells in bone marrow, spleen and liver with all other organs being negative. Adhesion assays of 5T2MM cells to different types of endothelial cells demonstrated a selective adhesion of 5T2MM cells to bone marrow and liver and not to lung endothelial cells. We here demonstrate that the specific in vivo localization of the 5T2MM cells is a result of the combination of a selective entry/adhesion of the 5T2MM cells in the bone marrow, spleen and liver, and a selective survival and growth of these tumour cells in the bone marrow and spleen but not in the liver.

Animals↗
PubMed2000

Homing of the myeloma cell clone.

The presence of myeloma cells in the blood circulation. implicates that these cells must have the potential to extravasate and home to the bone marrow environment. Using the 5T2 MM mouse model, we could demonstrate that the restricted localization of myeloma cells in the bone marrow is the result of selective migration of myeloma cells in the bone marrow combined with a selective growth of the tumour cells in the bone marrow microenvironment. Moreover, we showed that 5T2 MM cells bind in vitro selectively to bone marrow-derived endothelial cells (EC) and not to lung-derived EC. In order to identify which chemotactic molecules mediate the transendothelial migration of myeloma cells, we examined the motility-inducing effect of different extracellular matrix proteins on myeloma cell lines. We found that laminin-1 a major component of the basement membrane, triggers the motility of both human myeloma cells and 5T2 MM cells, through the 67 kD laminin receptor. Because of the broad distribution of laminin in extracellular matrices throughout the body, it is clear that this molecule on itself can not be the only factor that determines the specificity of myeloma cell homing. In the 5T2 MM model we identified IGF-1 as a more specific bone marrow derived chemoattractant for myeloma cells. In addition we demonstrated that the marrow microenvironment can upregulate the expression of the IGF-1 receptor on 5T mouse myeloma cells. In the end phase of the disease, increasing numbers of myeloma cells are detectable in the peripheral blood and extramedullary tumour growth can occur. We found that the stroma-independent variant of the human MM5 myeloma cell line showed an increased in vitro motility as compared to the stroma-dependent variant. By representational difference analysis we demonstrated that the stroma-dependent MM5 cells show a downregulation of the motility-related protein (MRP-I CD9) which might reflect the involvement of this molecule in the regulation of myeloma cell extravasation.

Animals↗
PubMed2000

Bisphosphonates--mechanisms of action in multiple myeloma.

Bisphosphonates are a class of anti-resorptive drugs, which are effective in the treatment of osteoclast-mediated bone disease, including the osteolytic bone disease. which is a major clinical feature of patients with multiple myeloma. Recently, increases in survival following treatment with pamidronate have been observed in some patients with multiple myeloma, raising the possibility that bisphosphonates may also have an anti-tumour effect. We have demonstrated that bisphosphonates can have an anti-tumour effect in human myeloma cell in vitro, and that these anti-tumour effects induced by potent nitrogen-containing bisphosphonates are a result of inhibition of enzymes of the mevalonate pathway. However, we and others have been unable to demonstrate an anti-tumour effect of the potent bisphosphonate ibandronate in vivo, using murine models of multiple myeloma. It is therefore likely that only by studying patients receiving bisphosphonates will we be able to determine whether these compounds have a clinically important anti-tumour effect.

Animals↗
PubMed1999

Insulin-like growth factor-1 acts as a chemoattractant factor for 5T2 multiple myeloma cells.

The chemotactic and growth-stimulatory effect of insulin-like growth factor 1 (IGF-1) was investigated in the experimental mouse 5T2 multiple myeloma (MM) model. Chemotaxis was analyzed by classical checkerboard analysis. Bone marrow fibroblasts-conditioned medium exhibited a chemotactic effect on 5T2 MM cells that could be neutralized by adding a blocking antibody to IGF-1. On the other hand, exogenously added IGF-1 also had a chemotactic effect on the 5T2 MM cells. Moreover, in vitro analysis demonstrated that transmigrated 5T2 MM cells have a higher expression of IGF-1 receptor, both in bone marrow-conditioned medium and in IGF-1-induced chemotaxis, in comparison to cells before migration. When analyzed in vivo, 18 hours after injection of the heterogeneous 5T2 MM population, 5T2 MM cells present in the bone marrow show a higher expression of the IGF-1 receptor than their counterparts before injection. When the proliferative effect of IGF-1 was analyzed, no stimulation was observed, which is in contrast to the influence of bone marrow-conditioned medium and interleukin-6. Our results suggest a causal relationship between the presence of IGF-1 in the bone marrow and the chemotaxis of MM cells to and their subsequent presence in the bone marrow.

Animals↗
PubMed1999

Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) DNA sequences are absent in leukapheresis products and ex vivo expanded CD34+ cells from multiple myeloma patients.

Recently it was reported that Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) infects bone marrow (BM) dendritic cells (DC) in multiple myeloma (MM) patients and therefore might play a role in MM development. Because of the use of myeloid growth factors like GM-CSF and G-CSF for the mobilization of peripheral blood progenitor cells (PBPC), the subsequent increase of DC precursors might imply a risk for KSHV contamination in PBPC grafts. Therefore, in this study leukapheresis products and ex vivo cultured CD34+ cell suspensions were analysed. KSHV DNA could not be amplified in any of them.

Antigens, CD34↗
PubMed1999

Different expression of adhesion molecules on CD34+ cells in AML and B-lineage ALL and their normal bone marrow counterparts.

The expression of adhesion molecules on CD34+ cells in acute myeloid leukemia (AML) and B-lineage acute lymphoblastic leukemia (B-lineage ALL) was compared with that on the myeloid and B-lymphoid CD34+ cells in normal bone marrow. Bone marrow aspirates of 10 patients with AML, 8 patients with B-lineage ALL and of 6 healthy volunteers were examined. The phenotype of the CD34+ cells was determined with a double immunofluorescence method and flow cytometry. CD34+ cells in AML and B-lineage ALL showed a lower expression of VLA-2 and VLA-3 and a higher expression of ICAM-1 and LFA-3 than their normal bone marrow counterparts. AML CD34+ cells had less L-selectin but more VLA-5 on their surface membrane than normal myeloid CD34+ cells. B-lineage ALL CD34+ cells showed an overexpression of LFA-3. In individual patients deficiencies or over-expression of the beta1 integrin chain, VLA-4, PECAM-1 or HCAM also occurred. An abnormal adhesive capacity of the leukemic cells may influence their proliferation, their localisation and apoptosis. An aberrant expression of adhesion molecules may be used for the detection of minimal residual leukemia in these patients.

Acute Disease↗
PubMed1998

Homing behaviour of the malignant cell clone in multiple myeloma.

Multiple myeloma (MM) represents a B cell malignancy characterised by the presence of a monoclonal population of end-stage B cells in the bone marrow. Although fully matured bone marrow plasma cells are the predominant cell type in MM, there is much evidence that also more immature B cells are included in the malignant cell clone which are considered to be the myeloma precursor cells. The fact that these cells are detectable in the blood circulation and that their number increases with disease progression, makes it very likely that they represent the component of the tumour clone that mediates disease dissemination. This implies that these cells must have the potential to extravasate and home to the bone marrow environment. Like the migration mechanisms used by normal leukocytes and/or metastatic tumour cells of non-haematopoietic origin, it can be assumed that this bone marrow homing process is mediated by adhesive interactions and chemotactic signals provided by the microenvironment of the tumour. Once in the bone marrow compartment, myeloma cells will receive the appropriate signals to grow and survive. This aspect of tumour-homing is found to be the result of a functional interplay between the myeloma cells and the surrounding microenvironment, involving the action of several cytokines and adhesion molecules. In the end phase of the disease, myeloma cells can lose their stroma-dependency resulting in extramedullary tumour growth. We review normal B cell homing and discuss molecular mechanisms that determine the homing behaviour of the malignant cell clone in MM.

Animals↗
PubMed1998

Monitoring of C-reactive protein after allogeneic bone marrow transplantation identifies patients at risk of severe transplant-related complications and mortality.

Patterns of C-reactive protein (CRP) release were derived from frequent CRP measurements in a cohort of 66 consecutive patients receiving allogeneic bone marrow transplants (BMT) in our unit. Based on a retrospective study of clinical events occurring within the first 40 days after BMT, patients with major transplant-related complications (MTC+ group, n = 22) could be separated from those with fever or mild complications only (MTC- group, n = 44). Treatment-related mortality in the MTC+ group was significantly higher: 32 vs 0% (P < 0.001). Major complications included veno-occlusive liver disease (VOD), severe endothelial leakage syndrome (ELS), pneumonitis and acute GVHD >II. The severity of complications was reflected by the patterns of CRP release with continuously high levels preceding the maximal signs and symptoms of MTC. Univariate analysis showed that, among other variables (sex, age, disease status at transplant, +/- TBI in the conditioning regimen, +/- use of myeloid growth factors after BMT, time to reach PN >200/mm3), three factors were significantly associated with MTC: maximal levels of CRP during the post-transplant episode (CRPmax) (296.6 +/- 91.8 vs 88.9 +/- 55.8 mg/100 ml, P < 0.001), the use of unmanipulated graft (no T depletion) (46.9 vs 12.5%, P < 0.009) and the CRP level on the day of BMT (CRPo) (42.7 +/- 55.4 vs 18.2 +/- 19.5, P = 0.045). In multivariate analysis, using a stepwise logistic regression model including the same variables, CRPmax appeared to be the strongest independent variable (P < 0.001) and a reliable (94% accuracy) parameter to assess the risk of MTC. Based on this model, CRP levels of 200 and 300 mg/100 ml are associated with a risk of 48 and 94% of developing MTC, respectively. We conclude that CRP monitoring after BMT identifies patients at risk of severe transplant-related complications and mortality.

Acute Disease↗
PubMed1998

Differential gene expression of the neural cell adhesion molecule (N-CAM) in a panel of multiple myeloma cell lines.

A striking feature of myeloma plasma cells concerns their expression of the neural cell adhesion molecule (N-CAM). The regulation of this particular expression is, however, not known. In this study, the N-CAM (CD56) gene regulation was examined in a panel of multiple myeloma (MM) cell lines. In this panel, both N-CAM-positive and -negative cells were analysed, reflecting the in vivo situation where a minority of MM patients have CD56-negative plasma cells at diagnosis or where in cases of extramedullary involvement CD56 expression decreases. At least two N-CAM mRNAs were found in the cell lines expressing the 140 kDa isoform. With one exception, no N-CAM transcripts could be detected in the N-CAM-negative cell lines. No structural differences could be found in the genomic organization of the N-CAM gene, or in the regulatory promoter region when CD56-positive and -negative cell lines were compared. In transfection studies, however, transcriptional activity of the N-CAM promoter was observed in N-CAM-negative cells, leading us to conclude that the up-regulation of N-CAM in MM cannot be explained by a simple transcriptional gene activation.

Antigens, CD↗
PubMed1998

Homing mechanisms in the biology of multiple myeloma.

Throughout the last decades, new developments in cellular and molecular immunology have led to a better insight in the biological nature of MM. Ever since, MM has also been regarded as a tool for studying basic concepts of the terminal B cell differentiation. The first aim of our research work, was to clarify the intraclonal maturation of the tumor clone by examining the existence of myeloma precursor cells at the genetic level. We found that myeloma patients have monoclonal B cells in the peripheral blood and bone marrow which are more immature as the malignant plasma cells and have passed through the stage of antigen selection in the germinal centre. The detection of these myeloma-related cells in the circulation implicates that these cells must be equipped with the appropriate surface receptors that allow transendothelial migration. Once entered in the marrow compartment, the myeloma cells anchor to the stromal environment where they receive the appropriate signals to proliferate and differentiate. We demonstrated that the bone marrow plasma cells express several adhesion molecules that have the potential to interact with stromal elements. We found that myeloma cell lines can bind to fibronectin (FN) and moreover are able to produce FN themselves. Functional assays revealed that FN plays only a minor role in myeloma cell binding to intact stroma, indicating the existence of other and/or multiple adhesive mechanisms. The growth of myeloma cells in the marrow compartment is not only dependent on adhesive interactions but also included the action of locally produced soluble factors. Although IL-6 has been identified as the major growth factor of myeloma cells, maintenance of tumor growth in vivo depends on one or more additional stroma-derived factors. We could establish a unique human myeloma cell line (MM5.1) that grows only in the presence of cultured human bone marrow stroma or stromal conditioned medium and not when cultured with exogeneous IL-6 alone. More recently a stroma-independent variant (MM5.2) of this line was obtained. We found that the growth of MM5.1 cells is mediated by signaling via the gp-130 transducer chain and involves IL-6 acting with a cofactor. The nature of this stromal cofactor is currently under investigation. Both variants of the cell line are also used to study differential expression of genes that are involved in clonal progression towards stroma-independency and extramedullary growth, as can be observed in patients with end stage disease.

B-Lymphocytes↗
PubMed1997

Organ involvement and phenotypic adhesion profile of 5T2 and 5T33 myeloma cells in the C57BL/KaLwRij mouse.

The aim of this study was to evaluate the tissue infiltration and phenotypic adhesion profile of 5T2 multiple myeloma (MM) and 5T33 MM cells and to correlate it with that observed in human disease. For each line, 30 mice were intravenously inoculated with myeloma cells and at a clear-cut demonstrable serum paraprotein concentration; mice were sacrificed and a number of organs removed. The haematoxylin-eosin stainings on paraffin sections were complemented with immunohistochemistry using monoclonal antibodies developed against the specific MM idiotype. When analysed over time, 5T2 MM cells could be observed in bone marrow samples from week 9 after transfer of the cells. For the 5T33 MM, a simultaneous infiltration was observed in bone marrow, spleen and liver 2 weeks after inoculation. Osteolytic lesions consistently developed in the 5T2 MM, but this was not consistent for 5T33 MM. PCNA staining showed a higher proliferative index for the 5T33 MM cells. The expression of adhesion molecules was analysed by immunohistochemistry on cytosmears: both 5T2 MM and 5T33 MM cells were LFA-1, CD44, VLA-4 and VLA-5 positive. We conclude that both lines have a phenotypic adhesion profile analogous to that of human MM cells. As the 5T2 MM cells are less aggressive than the 5T33 MM cells, their organ distribution is more restricted to the bone marrow and osteolytic lesions are consistently present, the former cell line induces myeloma development similar to the human disease.

Animals↗