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M Introna

Publications and source records attributed to M Introna.

At least 19 recordsLinked to original sources

Rapid and massive expansion of cord blood-derived cytokine-induced killer cells: an innovative proposal for the treatment of leukemia relapse after cord blood transplantation.

We have used a standardized 21-day expansion protocol to produce cytokine-induced killer (CIK) cells starting from very small amounts of nucleated cells (approximately 15 x 10(6) cells) isolated from cord blood. Mononuclear cells are stimulated with anti CD3 (OKT3) and IFNgamma and then expanded with IL-2. Moreover, we show that washouts of cord blood units bags (at the end of the infusion) may be sufficient to yield almost 500 x 10(6) CIK by the same expansion protocol. CIK cells show strong cytotoxic activity against a variety of tumor target cell lines including B and T lymphomas and myeloid leukemias. More importantly, expanded cord blood-derived CIK cells are cytotoxic against fresh leukemic blasts and express perforin, granzyme and NKG2D molecule at high levels. The same in vitro protocol has already been used to expand CIK cells from peripheral blood of adult donors under GMP conditions and therefore these observations open up the possibility of imagining a future clinical application of leukemia relapse following cord blood transplantation with CIK cells obtained from the same cord blood unit.

Antigens, Differentiation↗

Gemtuzumab ozogamicin (Mylotarg) has therapeutic activity against CD33 acute lymphoblastic leukaemias in vitro and in vivo.

Gemtuzumab ozogamicin (GO) is a humanized anti-CD33 antibody conjugated with the cytotoxic drug calicheamicin and approved for the treatment of relapsed acute myeloid leukaemia. As approximately 18% of acute lymphoblastic leukaemias (ALL) are also CD33 positive, we have investigated the cytotoxic activity of GO on CD33+ ALL cells in vitro and in vivo. 10 ng/ml GO induced 30-95% inhibition of thymidine uptake and 30-70% cell death in four freshly isolated and one in vivo passaged CD33+ ALL-cell cultures. Furthermore, an in vivo model of a CD33+ ALL carrying the Philadelphia chromosome [t(9;22)] was established. 5 x 10(6) ALL-2 cells inoculated in the tail vein of severe combined immunodeficient mice engrafted into haematopoietic organs, reaching a mean of 70%, 61% and 69% human CD45+ cells in bone marrow, spleen and liver, respectively, at 35 d. To test the therapeutic activity of GO, 50 or 100 microg immunotoxin was inoculated i.p. on days 7, 11 and 15 following tumour-cell inoculation. GO treatment dramatically inhibited expansion of ALL-2 cells in all tested organs and increased survival of tumour-injected animals by 28-41 d, relative to controls. These data demonstrated that GO is active both in vitro and in vivo against CD33+ ALL cells.

Aminoglycosides↗

Molecular evidence of inefficient transduction of proliferating human B lymphocytes by VSV-pseudotyped HIV-1-derived lentivectors.

Lentiviral vectors are attractive tools to transduce dividing and nondividing cells. Human tonsillar B lymphocytes have been purified and induced to proliferate by the addition of anti-CD40 + IL-4 or anti-CD40 + anti-micro signals and transduced at high MOI with a VSV pseudotyped lentivector carrying the eGFP gene under the control of the PGK promoter. Parallel cultures of PHA-stimulated T lymphocytes containing a comparable amount of cycling cells during the infection reached over 70% eGFP transduction. By contrast, only less than 3% B lymphocytes became eGFP positive after 7 days from transduction. Molecular analysis of the viral life cycle shows that cytoplasmic retrotranscribed cDNA and nuclear 2LTR circles are detectable at lower levels and for a shorter period of time in proliferating B cells with respect to proliferating T lymphocytes. Moreover, FACS-sorted eGFP-positive and negative B cell populations were both positive for the presence of retrotranscribed cDNA and 2LTR circles nuclear forms. By contrast, nested Alu-LTR PCR allowed us to detect an integrated provirus in FACS-sorted eGFP-positive cells only. Together with the demonstration that infection in saturation conditions led to an increase in the percentage of transduced cells (reaching 9%), these findings suggest that in proliferating B lymphocytes, lentiviral transduction is an inefficient process blocked at the early steps of the viral life cycle possibly involving partially saturable restriction factors.

Active Transport, Cell Nucleus↗

Functional transfer of CD40L gene in human B-cell precursor ALL blasts by second-generation SIN lentivectors.

Three different second-generation lentiviral self-inactivating vectors containing CMV, EF1alpha and PGK promoter, respectively, and all carrying the exogenous GFP gene, were compared for expression in human B-cell precursor ALL blasts. At a comparable percentage of transduction and vector DNA copy number, CMV clearly showed better efficiency of transcription. Human bone marrow stromal cells were favored compared to the MRC-5 cell line, as support for cell viability during infection. Cells were infected and analyzed after variable culture times ranging from 4 to 12 days, to reduce the possibility of pseudotransduction. In 10/14 samples, we detected more than 20% GFP-positive cells after exposure to high-titer viral supernatants. We then tested a similar vector carrying the human CD40L cDNA and, in similar infection conditions, obtained more than 20% transduction in 6/6 samples. The levels of transduction obtained were sufficient to induce the upregulation of CD83 molecule in cocultured immature dendritic cells.

CD40 Ligand↗

Modulation of cell cycle by graded expression of MLL-AF4 fusion oncoprotein.

Acute lymphoblastic leukemia (ALLs) expressing MLL-AF4, the fusion product of t(4;11)(q21;q23), show marked leucocytosis and extramedullary disease in multiple organs, respond poorly to chemotherapy and have poor prognosis. In vitro, leukemic cells with the t(4;11) show resistance to serum deprivation-induced or interferon gamma-regulated CD95-mediated apoptosis. In addition, t(4;11) cells have prolonged doubling time and lower percentage of cells in cycle compared to non-t(4;11) B lineage cell lines. In this study, we examine the time- and level-dependent effects of MLL-AF4 conditional expression on cell cycle and differentiation of myelomonocytic leukemia cell line U937. By varying the concentration of tetracycline in growth media, we found that increasing levels of MLL-AF4 expression result in a progressive decrease in growth rate and fraction of S phase cells, paralleled by an increase in percentage of cells expressing CD11b. Our results demonstrate a dosage-dependent effect of MLL-AF4 fusion oncoprotein on cell cycle progression, with increasing expression levels resulting in the accumulation in G1, prolonged doubling time, both findings that might be responsible for the increased resistance to etoposide-mediated cytotoxicity. We propose the cell cycle control exerted by MLL-AF4 may be responsible of resistance to cell-death promoting stimuli in leukemia carrying the t(4;11) translocation.

Cell Differentiation↗

Characterization of CD20-transduced T lymphocytes as an alternative suicide gene therapy approach for the treatment of graft-versus-host disease.

We have previously proposed the CD20 molecule as a novel suicide gene for T lymphocytes in the context of allogeneic bone marrow transplantation, because CD20 can be used both as a selection marker and as a killer gene after exposure to the anti-CD20 therapeutic antibody rituximab. We now report on preclinical studies using this novel system, in which the best transduction protocol, reproducibility, yield, feasibility, and functionality of the transduced T lymphocytes have been investigated with a large donor series. Wild-type human CD20 cDNA was transduced into human T lymphocytes, using a Moloney-derived retroviral vector. Alternative protocols were tested by employing either one or four spinoculations (in which cells are centrifuged in the presence of retroviral vector supernatant) and stimulating T cells with phytohemagglutinin (PHA) or anti-CD3/CD28. One spinoculation alone was sufficient to obtain approximately 30% CD20-positive cells within four experimental days. Four spinoculations significantly increased transduction to 60%. A small difference in transduction efficiency was observed between the two stimulation methods, with PHA being superior to anti-CD3/CD28. Transduced cells could be purified on immunoaffinity columns, with purity reaching 98% and yield being on average 50%. Finally, 86-97% of immunoselected T lymphocytes could be killed in vitro with rituximab and complement. More importantly, the CD20 transgene did not alter the functionality of T lymphocytes with respect to allogeneic recognition and cytotoxic response, anti-Epstein-Barr virus cytotoxic response, antigenic response to tetanus toxoid antigen, interleukin 2 (IL-2), IL-4, and interferon gamma production; chemotaxis in the presence of stromal cell-derived factor 1, phenotype for several activation markers including HLA-DR, CD25, CD69, and CD95, and T cell repertoire.

Antigens, CD20↗

CD40 ligand-stimulated B cell precursor leukemic cells elicit interferon-gamma production by autologous bone marrow T cells in childhood acute lymphoblastic leukemia.

Childhood B cell precursor acute lymphoblastic leukemia (BCP-ALL) cells, collected from bone marrow (BM) at diagnosis, were cultured, after thawing, on allogeneic human bone marrow stroma (HBMS) for 48 h in the presence of a soluble trimeric CD40 ligand (stCD40L) molecule. HBMS maintained leukemic cells viability in all tested cases (mean viability 85%). Under these culture conditions we noticed upregulation or de novo expression of costimulatory molecules CD40, CD80 (B7-1) and CD86 (B7-2) in 22/22, 15/23 and 21/23 cases, respectively. Upregulation, in terms of fluorescence intensity, was also observed in the expression of MHC I, MHC II, CD54 (ICAM 1) and CD58 (LFA 3) molecules. HBMS alone, although to a lesser extent, was able to induce modulation of these molecules, but not CD80, in a similar proportion of cases. Neither stCD40L nor HBMS induced modulation of CD10 and CD34 molecules. Moreover, in 4/4 tested cases, stCD40L-stimulated ALL cells were able to induce allogeneic T cells proliferation. To evaluate whether leukemia-reactive T cells were detectable in the BM of ALL patients at diagnosis, stCD40L-stimulated ALL cells were co-cultured with autologous T cells (ratio 1:1), isolated from BM at diagnosis, for 4 days and a 24 h ELISPOT assay was applied to detect the presence of interferon-gamma (IFN-gamma)-producing cells. In four of seven cases IFN-gamma-producing cells were detected with frequencies of 1/900, 1/1560, 1/2150 and 1/1575 autologous T cells. These data confirm that stCD40L exposure can activate the antigen-presenting cell (APC) capacity of BCP-ALL cells cultured on HBMS and that ELISPOT assay can be used to measure the frequency of leukemia-reactive autologous T cells in the BM of ALL patients even after short-term culture with stCD40L-stimulated ALL cells.

Adolescent↗

CD20 levels determine the in vitro susceptibility to rituximab and complement of B-cell chronic lymphocytic leukemia: further regulation by CD55 and CD59.

Complement-dependent cytotoxicity is thought to be an important mechanism of action of the anti-CD20 monoclonal antibody rituximab. This study investigates the sensitivity of freshly isolated cells obtained from 33 patients with B-cell chronic lymphocytic leukemia (B-CLL), 5 patients with prolymphocytic leukemia (PLL), and 6 patients with mantle cell lymphoma (MCL) to be lysed by rituximab and complement in vitro. The results showed that in B-CLL and PLL, the levels of CD20, measured by standard immunofluorescence or using calibrated beads, correlated linearly with the lytic response (coefficient greater than or equal to 0.9; P <.0001). Furthermore, the correlation remained highly significant when the 6 patients with MCL were included in the analysis (coefficient 0.91; P <.0001), which suggests that CD20 levels primarily determine lysis regardless of diagnostic group. The role of the complement inhibitors CD46, CD55, and CD59 was also investigated. All B-CLL and PLL cells expressed these molecules, but at different levels. CD46 was relatively weak on all samples (mean fluorescence intensity less than 100), whereas CD55 and CD59 showed variability of expression (mean fluorescence intensity 20-1200 and 20-250, respectively). Although CD55 and CD59 levels did not permit prediction of complement susceptibility, the functional block of these inhibitors demonstrated that they play an important role in regulating complement-dependent cytotoxicity. Thus, lysis of poorly responding B-CLL samples was increased 5- to 6-fold after blocking both CD55 and CD59, whereas that of high responders was essentially complete in the presence of a single blocking antibody. These data demonstrate that CD20, CD55, and CD59 are important factors determining the in vitro response to rituximab and complement and indicate potential strategies to improve the clinical response to this biologic therapy.

Antibodies, Monoclonal↗

Synergism between fludarabine and rituximab revealed in a follicular lymphoma cell line resistant to the cytotoxic activity of either drug alone.

We have shown previously that the anti-CD20 chimaeric monoclonal antibody rituximab exerts its effects on neoplastic B-lymphoma cell lines in part via complement-dependent cytotoxicity. In addition, membrane expression levels of complement inhibitory proteins CD55 and CD59 play a role in determining susceptibility to lysis. We have identified one t(14;18)-positive human B-cell non Hodgkin's lymphoma cell line (Karpas 422) that is resistant to rituximab and complement and used it for subsequent studies on the possible interaction between this novel therapeutic agent and established antineoplastic drugs. We have exposed Karpas to several chemotherapeutic agents (doxorubicin, idarubicin, cisplatin, taxol) for different time periods and subsequently exposed the cells to rituximab and human complement. The combination of these drugs with rituximab induced an additive cytotoxic effect. In contrast, exposure to fludarabine (1 microg/ml for 48-72 h) showed a synergistic effect, with cell lysis increasing from 10% to 20% using fludarabine or rituximab and complement alone to about 70% with both cytotoxic agents. Analysis of the mechanism for this synergistic effect showed that fludarabine downmodulates the membrane expression of CD55 (from 96% to 55% positive cells) without significantly altering CD20 levels. Northern analysis demonstrated that fludarabine induced a general downmodulation of steady state mRNA levels with no change in transcription rate detected in run-off assays. The study of the effect of fludarabine and rituximab in six freshly isolated B-cell chronic lymphocytic leukaemia (B-CLL) samples showed that, in most cases, fludarabine has an additive cytotoxic activity with rituximab and complement. This report gives a rational support for clinical studies with combinations of drugs, including monoclonal antibodies and fludarabine.

Antibodies, Monoclonal↗

Efficient lentiviral transduction of primary human acute myelogenous and lymphoblastic leukemia cells.

BACKGROUND AND OBJECTIVES: Gene manipulation and cell vaccines represent innovative strategies to enhance the immunogenicity of cancer cells. We adopted a defective lentivirus derived from the human immunodeficiency virus (HIV)-1 backbone and carrying the enhanced green fluorescent protein (EGFP) gene to transduce primary human acute myelogenous leukemia (AML) and B-precursor acute lymphoblastic leukemia (ALL) cells. DESIGN AND METHODS: AML blasts were maintained with or without cytokines (stem cell factor, FLT3 ligand and interleukin 3) for 48 hours, and successively infected with two spin infection cycles. ALL blasts were cultured on a murine S17 stromal cell line. RESULTS: As regards AML cells, the efficiency of infection at 7 days varied from 8.4 to 37%. As confirmed by cell cycle analysis, cells were, in most of the cases, blocked in different phases of the cycle and did not proliferate during culture: the infection was therefore obtained in the absence of cell proliferation. In contrast, the maintenance of optimal cell viability was of fundamental importance for obtaining good infection levels. As regards ALL blasts, the percentages of infection after 3 days varied from 4.4 to 21%. INTERPRETATION AND CONCLUSIONS: These preliminary data suggest that gene delivery into primary human AML and B-precursor ALL cells by an HIV-1 derived lentiviral vector could represent a strategy for engineering leukemic cells for use as cancer vaccines.

Bone Marrow Cells↗

Isolation and characterization of the human A-myb promoter: regulation by NF-Y and Sp1.

The A-myb transcription factor shows a restricted tissue distribution and is cell cycle regulated. Furthermore its deregulation has profound effects on the growth and/or differentiation of the cells in which it is normally expressed. We have therefore characterized its promoter. A 12 kb genomic clone was isolated that comprises the first exon, part of the first intron as well as upstream regulatory sequences. Multiple transcription start sites have been identified which operate in both B lymphocytes and epithelial cells and the upsteam region was shown to have promoter, activity. The boundaries of the minimal promoter region (-183-14), of a positive upstream (-538-183) and a negative downstream regulatory region (NRE) (+83+374) have been defined. The NRE is promoter- and orientation-independent but position specific. The A-myb minimal promoter is GC-rich, does not contain any TATA box but has a functional CCAAT box. The CCAAT box and minimal promoter is highly conserved in the corresponding murine sequence. The CCAAT box efficiently binds the NF-Y complex and its mutation decreases basal promoter activity by 50%. Two Sp1 binding sites are present upstream from the CCAAT box which can bind Spl and contribute to A-myb promoter activity by 70 and 30%, respectively. The two Sp1 sites and CCAAT box together contribute to over 80% of A-myb basal promoter activity and are therefore the major regulatory elements. Finally, we show that the promoter is cell cycle regulated and that the SP1 and CCAAT elements are required for S phase induction.

Animals↗

PTX3, A prototypical long pentraxin, is an early indicator of acute myocardial infarction in humans.

BACKGROUND: Inflammation is an important component of ischemic heart disease. PTX3 is a long pentraxin whose expression is induced by cytokines in endothelial cells, mononuclear phagocytes, and myocardium. The possibility that PTX3 is altered in patients with acute myocardial infarction (AMI) has not yet been tested. METHODS AND RESULTS: Blood samples were collected from 37 patients admitted to the coronary care unit (CCU) with symptoms of AMI. PTX3 plasma concentrations, as measured by ELISA, higher than the mean+2 SD of age-matched controls (2.01 ng/mL) were found in 27 patients within the first 24 hours of CCU admission. PTX3 peaked at 7.5 hours after CCU admission, and mean peak concentration was 6.94+/-11.26 ng/mL. Plasma concentrations of PTX3 returned to normal in all but 3 patients at hospital discharge and were unrelated to AMI site or extent, Killip class at entry, hours from symptom onset, and thrombolysis. C-reactive protein peaked in plasma at 24 hours after CCU admission, much later than PTX3 (P<0.001). Patients >64 years old and women had significantly higher PTX3 concentrations at 24 hours (P<0.05). PTX3 was detected by immunohistochemistry in normal but not in necrotic myocytes. CONCLUSIONS: PTX3 is present in the intact myocardium, increases in the blood of patients with AMI, and disappears from damaged myocytes. We suggest that PTX3 is an early indicator of myocyte irreversible injury in ischemic cardiomyopathy.

Aged↗

A-myb rescues murine B-cell lymphomas from IgM-receptor-mediated apoptosis through c-myc transcriptional regulation.

A-myb is a member of the myb family of transcription factors, which regulates proliferation, differentiation, and apoptosis of hematopoietic cells. A-Myb expression is normally restricted to the proliferating B-cell centroblasts and transgenic mice overexpressing A-myb displayed enhanced hyperplasia of the lymph nodes. Because A-Myb is highly expressed in several subtypes of human B-cell neoplasias, we sought to determine whether the A-myb gene promoted proliferation and survival of B lymphocytes, using the WEHI 231 and CH33 murine B-cell lymphomas as models. Here, we show that ectopic expression of A-myb rescues WEHI 231 and CH33 cells from growth arrest and apoptosis induced by anti-IgM treatment. Previously, we demonstrated an essential role of the c-myc gene in promoting cell survival of WEHI 231 cells in response to a variety of apoptotic stimuli. Furthermore, we and others have shown that the c-myc gene is potently transactivated by A-Myb in several cell types. Thus, we sought to determine whether c-Myc would mediate the A-Myb antiapoptotic effect in B cells. Here we show that ectopic expression of A-myb leads to maintenance of c-myc expression, and that expression of antisense c-myc RNA ablates A-Myb-mediated survival signals. Thus, these findings strongly implicate the A-myb gene in the regulation of B-cell survival and confirm the c-myc gene as one of the downstream targets of A-myb in these cells. Overall, our observation suggests that A-myb expression may be relevant to the pathology of human B-cell neoplasias.

Animals↗

Inducible expression of the long pentraxin PTX3 in the central nervous system.

PTX3 is a prototypic long pentraxin consisting of a C terminal 203-amino acid pentraxin-like domain coupled with an N-terminal 178-amino acid unrelated portion. PTX3 is induced by primary proinflammatory signals in various cell types, most prominently macrophages and endothelial cells. Other long pentraxins, such as murine or rat neuronal pentraxin 1 (NP1) and human neuronal pentraxin 2 (NPTX2), are expressed in the central nervous system (CNS). The present study was designed to investigate whether PTX3 is expressed in the brain and to define the structures and cells involved. Intracerebroventricular (i.c.v.), but not i.v., injection of LPS induced high levels of PTX3 mRNA in the mouse brain. In contrast NP1 is constitutively expressed in the murine CNS and is not modulated by LPS administration. I.c.v. IL-1beta was also a potent inducer of PTX3 expression in the CNS, whereas TNFalpha was substantially less effective and IL-6 induced a barely detectable signal. Central administration of LPS and IL-1 induced PTX3 also in the periphery (heart), whereas the reverse did not occur. Expression of PTX3 was also observed in the brain of mice infected with Candida albicans (C. albicans) or Cryptococcus neoformans. (C. neoformans). The kinetics of PTX3 gene induction were consistently different between C. albicans- and C. neoformans-infected mice, according to the diverse outcome of the CNS immune reaction. In situ hybridization revealed that i.c.v. injection of LPS induced a strong PTX3 expression in presumptive glial cells, in the white matter (corpus callosum, fimbria) and meningeal pia mater as well as in dentate gyrus hilus and granule cells. No constitutive expression of PTX3 was detected. Central expression of PTX3 may amplify mechanisms of innate resistance and damage in the CNS. The possibility of a direct interaction of PTX3 with neuronal cells, as suggested for NPTX2, remains to be explored.

Animals↗

Biologic response of B lymphoma cells to anti-CD20 monoclonal antibody rituximab in vitro: CD55 and CD59 regulate complement-mediated cell lysis.

The chimeric anti-CD20 MAb rituximab has recently become a treatment of choice for low-grade or follicular non-Hodgkin's lymphomas (FL) with a response rate of about 50%. In this report, we have investigated the mechanism of action of rituximab on 4 FL and 1 Burkitt's lymphoma (BL) cell lines, 3 fresh FL samples and normal B cells in vitro. Rituximab efficiently blocks the proliferation of normal B cells, but not that of the lymphoma lines. We did not detect significant apoptosis of the cell lines in response to rituximab alone. All cell lines were targets of antibody-dependent cellular cytotoxicity (ADCC). On the other hand, human complement-mediated lysis was highly variable between cell lines, ranging from 100% lysis to complete resistance. Investigation of the role of the complement inhibitors CD35, CD46, CD55, and CD59 showed that CD55, and to a lesser extent CD59, are important regulators of complement-mediated cytotoxicity (CDC) in FL cell lines as well as in fresh cases of FL: Blocking CD55 and/or CD59 function with specific antibodies significantly increased CDC in FL cells. We conclude that CDC and ADCC are major mechanisms of action of rituximab on B-cell lymphomas and that a heterogeneous susceptibility of different lymphoma cells to complement may be at least in part responsible for the heterogeneity of the response of different patients to rituximab in vivo. Furthermore, we suggest that the relative levels of CD55 and CD59 may become useful markers to predict the clinical response. (Blood. 2000;95:3900-3908)

Antibodies, Monoclonal↗

A-Myb up-regulates Bcl-2 through a Cdx binding site in t(14;18) lymphoma cells.

In follicular lymphoma, bcl-2 is translocated to the immunoglobulin heavy chain locus leading to deregulation of bcl-2 expression. We examined the role of Myb proteins in the regulation of bcl-2 expression in lymphoma cells. We showed that A-Myb up-regulates bcl-2 promoter activity. Northern and Western analyses demonstrated that A-Myb was expressed in the DHL-4 t(14;18) cell line. In t(14;18) cells and mature B cells, A-Myb up-regulated bcl-2 expression, whereas B- and c-Myb had little effect on bcl-2 gene expression. Deletion analysis of the bcl-2 5'-region identified a region responsive to A-Myb in t(14;18) cells. A potential binding site for the Cdx homeodomain proteins was located in this sequence. Analysis of the A-Myb-responsive region by UV cross-linking experiments revealed that a 32-kDa protein formed a complex with this region, but direct binding by Myb proteins could not be demonstrated. A-Myb could be recovered along with Cdx2 when nuclear extracts were passed over the Cdx site. Mutagenesis of the Cdx binding site abolished binding by the 32-kDa protein and significantly reduced the ability of A-Myb to induce bcl-2 expression. A strong induction of bcl-2 P2 promoter activity was observed in cotransfection studies of DHL-4 cells with the A-Myb and Cdx2 expression vectors, and increased endogenous Bcl-2 protein expression was observed in B cells transfected with A-Myb and/or Cdx2 expression constructs.

Animals↗