Patrick Lacor

Catheter tip position as a risk factor for thrombosis associated with the use of subcutaneous infusion ports

AimsThe use of subcutaneous infusion ports has become standard practice to provide a long-term venous access in oncological patients. The aim of this retrospective study was to assess the different complications of infusion ports in our population and to identify predisposing factors.Patients and methodsWe reviewed the medical records of 437 patients who were followed at the Oncology/Haematology Department of our hospital. Of these patients, there were 370 (84.4%) with solid tumours and 58 (13.2%) with haematological disease. The position of the catheter tip was evaluated by reviewing the available chest radiographs or phlebographies.Main resultsAnalysis of the records showed that 346 patients (79.17%) had no complications. The most common complications after implantation were thrombosis (8.46%), catheter dysfunction (4.8%) and infections (4.4%). Univariate and multivariate analysis showed that catheter tip positioning was the most important predisposing risk factor for thrombosis. Catheter tips positioned in the brachiocephalic vein or in the cranial part of the superior vena cava were associated with a high risk of thrombosis. Other significant risk factors were gender and initial diagnosis. Female patients and patients with lung cancer also had an elevated risk of developing a thrombosis.ConclusionsCompared to other reports, we noted a higher rate of thrombosis and port dysfunction. Since catheter tip position was a predisposing factor for developing a thrombosis, correct catheter position has to be ensured during placement. Prophylactic antithrombotic treatment might be beneficial in the event of failure to position the catheter correctly.

Expression of cytoadhesion molecules (CD56, CD54, CD18 and CD29) by myeloma plasma cells

Recently we reported the expression of the human natural killer cell associated antigen CD56 (Leu 19/NKH1) in plasma cells of a majority of multiple myeloma (MM) patients. CD56 is known to be an isoform of the human neural adhesion molecule N‐CAM which is involved in homotypic adhesive interactions. By immunophenotyping using four CD56 specific monoclonal antibodies and immunoprecipitation analysis we here confirm that the Leu 19 antigen expressed by myeloma plasma cells is identical to N‐CAM and corresponds to the 145 kDa isoform. Because of the possible biological role of adhesion molecules on myeloma cells, we compared the expression of N‐CAM with the intercellular adhesion molecule 1 (ICAM‐1) and the β1 and β2 integrins. By immunogold‐silver staining of cytospin preparations of mononuclear cell suspensions, bone marrow plasma cells of 17 MM patients were analysed. Plasma cells expressed N‐CAM (CD56) in 14 patients, ICAM‐1 (CD54) in 16 patients, and β2 intergrins (CD18) in eight patients. β1 integrins (CD29) were expressed in all patients. The expression of β2 integrins was always very weak while N‐CAM, ICAM‐1 and the β1 integrins showed a moderate to strong positivity. The plasma cells of five haematological normal individuals lacked significant N‐CAM expression but were positive for ICAM‐1 and both integrin subgroups. One plasma cell leukaemia patient and two out of four end‐stage MM patients showed no expression of N‐CAM or β2 integrins on their circulating plasma cells. Among 11 previously established myeloma cell lines, surface expression of ICAM‐1 and the integrins was detected in most cases, while N‐CAM was present in only four lines. Most cell lines showed coexpression of the fibronectin receptors (VLA‐4 and VLA‐5) and the laminin receptor (VLA‐6). The collagen receptor (VLA‐2) was not expressed. The N‐CAM negative cell lines included four cell lines that were derived from plasma cell leukaemia patients. These results indicate that the expression of adhesion molecules is an intrinsic part of the biology of multiple myeloma.

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, nu2009=u200922) could be separated from those with fever or mild complications only (MTC− group, nu2009=u200944). Treatment-related mortality in the MTC+ group was significantly higher: 32 vs 0% (Pu2009<u20090.001). major complications included veno-occlusive liver disease (vod), severe endothelial leakage syndrome (els), pneumonitis and acute gvhdu2009>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 PNu2009>200/mm3), three factors were significantly associated with MTC: maximal levels of CRP during the post-transplant episode (CRPmax) (296.6u2009±u200991.8 vs 88.9u2009±u200955.8u2009mg/100u2009ml, Pu2009<u20090.001), the use of unmanipulated graft (no t depletion) (46.9 vs 12.5%, Pu2009<u20090.009) and the crp level on the day of bmt (crpo) (42.7u2009±u200955.4 vs 18.2u2009±u200919.5, Pu2009=u20090.045). In multivariate analysis, using a stepwise logistic regression model including the same variables, CRPmax appeared to be the strongest independent variable (Pu2009<u20090.001) and a reliable (94% accuracy) parameter to assess the risk of mtc. based on this model, crp levels of 200 and 300 mg/100u2009ml 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.

Adhesive interactions between tumour cells and bone marrow stromal elements in human multiple myeloma

Abstract:u2002 Long‐term bone marrow cultures (LTBMC) were established from marrow samples obtained from 6 myeloma patients and 5 healthy donors and were examined by in situ immunogold–silver staining. During the culture period, the established stroma in myeloma LTBMC revealed a lower level of confluency compared to the normal LTBMC. In addition, an increasing proportion of macrophages and osteoclasts was observed in the myeloma stroma throughout the culture period. Moreover, plasma cells were detectable by wk 8, mostly organized in small clusters. They strongly expressed VLA‐4 (6/6), H‐CAM (6/6), ICAM‐1 (6/6) and N‐CAM (3/6). In most cases, a weak expression of the other members of β1‐integrins was observed. The expression of β2‐integrins was always absent. Stromal fibroblasts were found to be weakly positive for VLA‐2, VLA‐3 and VLA‐5 and showed strong expression of VCAM‐1, H‐CAM and ICAM‐1. N‐CAM expression could not be detected. By comparing the adhesion molecule profile of the stromal cells in myeloma cultures with normal bone marrow (BM) cultures, no particular defects could be observed. The stroma displayed most of the potential ligands which could interact with adhesion molecules detected on the myeloma cells. Among these ligands we could find fibronectin and VCAM‐1 for VLA‐4, collagen I for VLA‐2 and VLA‐3 and laminin for VLA‐2, 3 and 6. Four myeloma cell lines, i.e. OPM‐1, U266, RPMI 8226 and JJN3, with a representative phenotype, were used to study the adhesive interactions of myeloma cells with the BM microenvironment. All the myeloma cell lines bound strongly to the marrow cell layers and also showed a high binding to purified fibronectin (FN). However, the adhesion of the cell lines to intact stroma could not be significantly inhibited by anti‐FN receptors antibodies. Nor could it be prevented when the latter were combined with anti‐H‐CAM, V‐CAM and ICAM‐1 antibodies, as tested in the JJN3 cell line. This implies that other unknown mechanisms contribute to the myeloma cell binding.

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

Abstract:u2002 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 β1 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.

Establishment and characterization of a human stroma-dependent myeloma cell line (MM5.1) and its stroma-independent variant (MM5.2)

Although IL-6 has been identified as a major growth factor in multiple myeloma (MM), it is believed that maintenance of tumor growth in vivo depends on one or more additional stroma-derived factors. We describe a new human myeloma cell line (MM5.1) that can be maintained in the presence of bone marrow-derived stromal cell layers, and not only when cultured with exogeneous IL-6. This cell line expresses the same immunoglobulin κ light chain RNA sequence as the patient’s original tumor cells, has a plasma cell morphology and expresses plasma cell antigens (cytoplasmic κ light chain, CD38, BB4). Without the presence of stromal factors, MM5.1 cells become apoptotic. A low proliferative effect was observed in the presence of oncostatin M (OSM) but other cytokines (IL-10, IL-11, stem cell factor (SCF) and leukemia inhibitory factor (LIF)) had no effect at all. We observed that MM5.1 cells also grow when physically separated from stromal cell layers by a 0.45u2009μm microporous membrane or when cultured in conditioned medium from stromal marrow cells. Unexpectedly, the growth in stromal supernatants was markedly inhibited by an anti-IL-6 antiserum and an anti-IL-6 receptor transducer chain (gp130)u2009mAb in a dose-dependent manner. This implies that MM5.1 cells are IL-6 responsive only when exposed to one or more additional soluble factor(s) derived from bone marrow stroma. Coculturing MM5.1 cells with IL-6 and cytokines that were described to increase the IL-6 responsiveness of myeloma cells (G-CSF, GM-CSF and IL-3) had no effect on the growth or survival. A strong proliferative effect was observed when MM5.1 cells were cultured with IL-6 and soluble IL-6 receptor (sgp80). However no sgp80 could be detected in stromal supernatants using a sensitive immunoassay. This indicates that sustained proliferation of the MM5.1 cell line depends on a combination of IL6 and at least one, thus far unidentified, stroma-derived factor. After more than 1 year in continuous culture, we could obtain a variant of the line (MM5.2) that shows an improved growth rate and grows stroma independently. Molecular analysis revealed clonal identity with the early passage form and Epstein–Barr virus antigen expression was negative. The two variants of this cell line offer a useful model to identify molecular mechanisms involved in clonal evolution towards stroma-independent growth of myeloma cells.

Growth factor receptor profile of CD34+ cells in AML and B‐lineage ALL and in their normal bone marrow counterparts

Abstract: Leukaemic cells show a low clonogenic activity and a heterogeneous proliferative response to growth factors. We investigated whether this could be due to an altered expression of growth factor receptors on the leukaemic precursors. Receptors for G‐CSF, stem cell factor (SCF), IL‐3, IL‐6 and IL‐7 were detected on CD34+ cells in AML and B‐lineage ALL with monoclonal antibodies and flow cytometry. The expression was compared with that on myeloid and B‐lymphoid CD34+ cells in normal bone marrow. Leukaemic CD34+ cells expressed the same receptors as their normal counterparts. AML and B‐lineage ALL could be distinguished by the growth factor receptor profile of their CD34+ cells. SCFR, G‐CSFR and IL‐6Rα were found in AML, IL‐7R in B‐lineage ALL and IL‐3Rα in both. IL‐3Rα was upregulated in AML and B‐lineage ALL CD34+ cells, while samples with low or high expression were present for the other receptors. This variable expression could correlate with the heterogeneous response of leukaemic cells to growth factors. Functional studies on isolated CD34+ cells are needed to investigate this further.

Severe thrombocytopenia secondary to cytomegalovirus infection in an immunocompetent adult.

A healthy 38-year-old man presented with a short history of a viral syndrome, accompanied by purpura and gingival bleeding. Examination of the blood showed a profound thrombocytopenia. Cytomegalovirus infection was diagnosed and a causal relationship between CMV infection and thrombocytopenia was assumed on clinical grounds. We successfully treated the patient with oral prednisone. In the discussion, we briefly mention the different hypothetical mechanisms leading to autoimmune thrombocytopenia.