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Biomedical subjects

C Bruyns

Publications and source records attributed to C Bruyns.

At least 37 records · Page 2Linked to original sources
PubMed1994

Cytokine gene transfer for the treatment of cancer.

Major progress has been made in the understanding not only of the molecular mechanisms involved in the pathogenesis of cancer, but also of the complex relations between cancer and the immune system. Among the more promising approaches of gene therapy for cancer is the manipulation of the immune system, with the development of an immune antitumoral systemic response. Transfer of some cytokine gene in tumor cells has especially been shown to induce an immune response protecting the animal against subsequent injection of parental tumor cells, and can even, in some cases, treat efficiently animals carrying a preexisting parental tumors. These new experimental data form the basis for the recent elaboration of a rapidly increasing number of clinical protocols using cytokine gene transfer for the treatment of human cancer.

Animals↗
PubMed1993

Interleukin 10 reduces the release of tumor necrosis factor and prevents lethality in experimental endotoxemia.

Because of its ability to efficiently inhibit in vitro cytokine production by activated macrophages, we hypothesized that interleukin (IL) 10 might be of particular interest in preventing endotoxin-induced toxicity. We therefore examined the effects of IL-10 administration before lipopolysaccharide (LPS) challenge in mice. A marked reduction in the amounts of LPS-induced tumor necrosis factor (TNF) release in the circulation was observed after IL-10 pretreatment at doses at low as 10 U. IL-10 also efficiently prevented the hypothermia generated by the injection of 100 micrograms LPS. Finally, pretreatment with a single injection of 1,000 U IL-10 completely prevented the mortality consecutive to the challenge with 500 micrograms LPS, a dose that was lethal in 50% of the control mice. We conclude that IL-10 inhibits in vivo TNF secretion and protects against the lethality of endotoxin in a murine model of septic shock.

Animals↗
PubMed1990

Increased expression of Ia antigens on B cells after neonatal induction of lymphoid chimerism in mice: role of interleukin 4.

BALB/c mice rendered chimeric at birth by injection of 10(8) (A/J X BALB/c)F1 spleen cells develop a lupus-like autoimmune disease linked to the activation of donor B cells by host T cells. As in vitro studies previously indicated that interleukin 4 (IL4) was a mediator of the interactions between T and B cells, we analyzed the intensity of Ia antigen expression on B cells of chimeric mice. Flow cytometric analysis with anti-Ia monoclonal antibodies (mAb) revealed that B cells from spleens and lymph nodes of 2-week-old chimeric BALB/c mice displayed a two- to threefold increase in membrane Ia antigen expression, this increase still being present in spleens of 30-week-old animals. An increase in Ia antigen expression was also found in the small number of donor B cells detected in spleens and lymph nodes of chimeric mice. IL4 was the major stimulus leading to increased B cell Ia antigen expression, as this phenomenon was substantially prevented by in vivo treatment of chimeric mice with the anti-IL4 11B11 mAb. In vitro experiments revealed that host splenic T cells of chimeric mice, while unable to generate anti-donor cytotoxic T lymphocytes, secreted significant amounts of IL 4 when stimulated in mixed lymphocyte cultures (MLC) with donor alloantigens. This IL4 secretion led to an increased expression of Ia antigens on donor-type F1 B cells present in MLC. No significant increase in Ia antigen expression was found on syngeneic BALB/c B cells co-cultured with T cells from chimeric mice unless A/J B cells were added to the cultures. Taken together, these findings indicate that increased Ia antigen expression on donor B cells is induced by IL4 secreted by anti-donor T cells. IL4 released in this setting also leads to increased Ia antigen expression on host B cells through a bystander effect.

Animals↗
PubMed1990

Persistence of anti-donor allohelper T cells after neonatal induction of allotolerance in mice.

BALB/c mice rendered tolerant to A/J alloantigens by neonatal injection of 10(8) (A/J X BALB/c)F1 spleen cells develop an autoimmune disease associated with a polyclonal activation of donor B cells. To study the mechanisms leading to donor B cell activation in tolerant mice, we prepared mixed lymphocyte cultures (MLC) between splenic T cells from neonatally injected mice and donor-type (A/J X BALB/c)F1 or third-party (C57BL/6 X BALB/c)F1 B cells. T cells from tolerized mice were unable to generate cytotoxic T lymphocytes, to proliferate or to secrete interleukin (IL)2 after stimulation with donor alloantigens in MLC. These T cell responses were present after MLC with third-party antigens, but were of lower intensity than those generated by control BALB/c T cells. In contrast, T cells from tolerized mice stimulated immunoglobulin production by donor-type (A/J X BALB/c)F1 B cells much more powerfully than T cells from control BALB/c mice. The stimulation of donor-type (A/J X BALB/c)F1 B cells was polyclonal, as attested by the levels of anti-hapten and anti-DNA antibodies in the MLC supernatants. IgM was the dominant isotype secreted in vitro, but IgG1 and IgG3 were also produced in significant amounts. Lysis experiments indicated that the T cells responsible for F1 B cell stimulation in MLC were CD4+ host T cells. These T helper cells were alloreactive since they did not stimulate syngeneic BALB/c B cells, and their effect on donor B cells was specifically blocked by anti-donor Ia monoclonal antibodies. Addition of anti-IL 4 monoclonal antibody to MLC between T cells from tolerant mice and (A/J X BALB/c)F1 B cells almost completely abolished the production of IgG1, but not that of IgM or IgG3. Taken together, these findings indicate that neonatal injection of alloantigens in BALB/c mice induces a state of dissociated tolerance, with unresponsiveness of anti-donor T cells secreting IL 2 on the one hand, and persistence of T cells responsible for B cell help and IL 4 secretion on the other hand.

Animals↗
PubMed1989

Detection of rotavirus in faecal specimens with a monoclonal antibody enzyme-linked immunosorbent assay: comparison with polyclonal antibody enzyme immuno-assays and a latex agglutination test.

Monoclonal antibodies have been produced against the 81/36F strain of rotavirus. One of them, was chosen as diagnostic reagent: it showed high ELISA reactivity with all the bovine, human and porcine rotavirus strains tested and reacted with VP6, structural protein product known to support the common rotavirus antigen. A sandwich ELISA procedure using the chosen monoclonal as "capture and detecting" antibody was performed to detect rotavirus in faecal samples from experimentally inoculated newborn calves: it always gave a negative response with meconium and a positive response for the stool specimens which rotavirus have been isolated. This assay was compared with Enzygnost and Slidex Rota Kit tests and with a non-commercial sandwich ELISA test using polyclonal antibodies: it showed more sensitivity than the agglutination test and was as sensitive as the other two tests to detect rotavirus in routine diagnostic material. The test evaluated showed no equivocal results.

Animals↗
PubMed1988

Autoimmunity and glomerulonephritis after neonatal induction of lymphoid chimerism in mice: role of donor B cells and host T cells.

Balb/c mice neonatally injected with semiallogeneic (A/J x Balb/c) F1 or (C57 BL/6 x Balb/c) F1 hybrid spleen cells develop autoantibodies, marked increase in serum levels of IgG1 and IgE, lymphoid hyperplasia, and immune-complex glomerulonephritis. F1 donor B cells play a dominant role in the pathogenesis of this autoimmune disease since B-cell chimerism is required for the occurrence of immunopathology, donor-specific allotype is expressed on serum anti-DNA antibodies, and substantial amounts of donor-derived immunoglobulins are present in the kidney eluate of chimeric mice. In vitro experiments indicate that T cells from diseased Balb/c mice induce activation of F1 donor B cells with secretion of anti-DNA antibodies. These findings suggest that a host-versus-graft reaction between recipient T cells and donor F1 B cells is responsible for the secretion of pathogenic antibodies in this model.

Animals↗
PubMed1988

Hyperactivity of donor B cells after neonatal induction of lymphoid chimerism in mice.

Balb/c mice made chimaeric by neonatal injection of semi-allogeneic (A/J x Balb/c)F1 hybrid spleen cells develop anti-DNA and rheumatoid factor-like antibodies in the context of hypergammaglobulinaemia with marked elevation of IgG1 and IgE serum levels. Chimaeric mice also display increased levels of antibodies to different haptens and to tobacco mosaic virus (TMV). The allotypic marker of the A/J strain is present on anti-DNA and anti-hapten antibodies. In addition, spleen cells of chimaeric mice spontaneously produce high levels of IgG1 and anti-DNA antibodies in vitro and this hyperactivity is abolished after lysis of donor lymphocytes. These findings indicate that polyclonal activation of donor B cells plays an important role in this model of autoimmunity.

Animals↗
PubMed1987

Chimerism and cytotoxic T lymphocyte unresponsiveness after neonatal injection of spleen cells in mice. Effects of T cell depletion and of a semiallogeneic or fully allogeneic inoculum.

Newborn Balb/c mice received a single neonatal injection of either (A/J x Balb/c) F1 hybrid spleen cells, T-cell-depleted (A/J x Balb/c) F1 hybrid spleen cells, or T-cell-depleted fully allogeneic A/J spleen cells. Chimerism was followed longitudinally during the life span by the detection of circulating donor allotype. At sacrifice, the percentage of donor cells in the spleen was measured, and cytotoxic T lymphocyte (CTL) reactivity to the tolerogen was tested. We found that T cell depletion of the semiallogeneic inoculum did not modify its capacity to generate persistent chimerism and CTL tolerance, while T-cell-depleted allogeneic cells were intrinsically deficient both in the induction and in the long-term maintenance of chimerism and CTL unresponsiveness.

Animals↗
PubMed1987

Autoimmune disease after neonatal injection of semi-allogeneic spleen cells in mice: involvement of donor B and T cells and characterization of glomerular deposits.

Balb/c neonates injected with semi-allogeneic (A/J x Balb/c) F1 hybrid spleen cells develop an autoimmune disease associated with an immune-complex glomerulonephritis. The successful induction and maintenance of B cell chimerism is required for the occurrence of autoimmunity. The percentage of chimeric mice displaying autoimmune features increases in parallel with the number of cells injected at birth. T cell depleted inocula although readily inducing B cell chimerism were found unable to induce hypergammaglobulinaemia, circulating immune complexes and glomerulonephritis. IgG1 is the most and IgG3 the least represented IgG isotype among the immunoglobulins deposited in the glomeruli. Immunoglobulins bearing donor (A/J) allotype are detected in the glomeruli of six out of 11 chimeric mice. Rheumatoid factor activity is significantly concentrated within the immunoglobulins eluted from the kidneys, whereas anti-DNA activity is not.

Animals↗
PubMed1985

[Allogenic interactions in immunopathology].

Allogeneic interactions associated with experimental graft-versus-host reaction are sometimes responsible for the development of autoantibodies, immune complex lesions and malignant lymphocytic proliferation. Hypergammaglobulinaemia reflects the activation of B cells, and T cell-associated responses are deeply depressed. Some of these abnormalities are also found in chimera mice following injection of semi-allogeneic cells. The place of allogeneic interactions in human pathology has not yet been determined, but they might intervene in the pathogenesis of some autoimmune and lymphoproliferative diseases and in the acquired immune deficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1978

Possible occurrence and meaning of lymphocytes bearing autoanti-idiotypic receptors during the immune response.

During an immune response, the increase in binding affinity of antibodies is followed by a fall. Lymphocytes bearing autoanti-idiotypic receptors were detected during a normal immune response. The kinetics of appearance and disappearance of such lymphocytes led us to propose a network model to explain the changes occurring in antibody properties during an immune response.

Animals↗
PubMed1978

Transplantable IgD immunoglobulin-secreting tumors in rat.

The LOU/C/Wsl rat inbred strain presents a high incidence of spontaneous malignant ileocecal immunocytomas or monoclonal immunoglobulin-secreting tumors. Some tumors have been transplanted in histocompatible animals over years without any change in their secretion products. Among approximately 600 different monoclonal proteins we have studied so far, we recognized six showing properties different from those of rat IgM, IgA, IgE, or IgG classes, and characteristic of the IgD class.

Animals↗
PubMed1976

Ontogeny of mouse B lymphocytes and inactivation by antigen of early B lymphocytes.

Taking advantage of recent findings about membrane fluidity, we have studied and compared the biosynthetic capacities of fetal or neonatal mouse B (bone-marrow derived) lymphocytes (until 10 days after birth) and adult B lymphocytes. Although both early and adult lymphocytes can synthesize surface immunoglobulins, they have a different physiological behavior after interaction with a ligand (anti-immunoglobulin sera or antigen), either in vivo or in vitro. Fetal and neonatal lymphocytes bearing surface immunoglobulins do not reexpress their membrane receptors after capping and endocytosis promoted by anti-immunoglobulin sera. On the other hand, adult lymphocytes resynthesize completely their receptors after the same treatment. Furthermore, intrafetal injections of hemocyanin in pregnant mice lead to a striking decrease in the number of hemocyanin-binding cells. It seems plausible that this non-reexpression of surface immunoglobulins could be the first step in tolerance establishment.

Age Factors↗
PubMedDate not supplied

Relationship between the synthesis of autoimmune antibodies and the formation of clusters of B, T and APC cells during the syngeneic mixed lymphocyte reaction in BALB/c and NZB mice: a technique for isolation of the spleen autoimmune compartment of non-immunized pathogen-free mice.

Cells from the spleens of non-immunized mice were cultured in horizontal tubes, rotating very slowly around their long axis. Under these conditions, the flux speed gradient of the cell suspension near the tube walls greatly increased the chances of cells coming into contact with one another. Mixed clusters of B, T and APC cells were soon found adhering firmly to the walls of the tube; cluster formation leveled off after about 3 h. The clustered cells were easily separated from those remaining in suspension and constituted a particular cell compartment comprising a maximum of 20-30% of the total. B cells from this compartment, cultured in complete medium for 48 h, almost exclusively produced IgM antibodies. Antibodies reacting with self antigens were so numerous in the culture medium that it is likely all IgM were self antibodies. That the clusters obtained under these conditions constituted a compartment of autoimmune cells is supported by previous work which showed that 20-30% of spleen cells secrete IgM antibodies almost exclusively. Cluster formation as a function of age was compared in NZB mice which are used as a model of lupus erythematosus, and in BALB/c mice which never manifest self-immune pathology. The number of cells found in clusters per whole spleen increased exponentially with age in NZB mice and linearly in BALB/c mice. The production of autoimmune antibodies as a function of age also increased exponentially for NZB mice and linearly in BALB/c mice, which provides further striking support for the hypothesis that the clusters formed constitute the autoimmune comportment.

Aging↗
PubMedDate not supplied

Cellular vaccines.

This project is devoted to the development of novel cellular vaccines designed to treat cancer patients. These cellular vaccines present and enhance immunogens, which will elicit a potent immune response. The goal is to achieve safe and effective immune reaction against the patient's own tumour. (1) Autologous cellular vaccines are prepared by processing circulating blood mononuclear cells outside of the patient's body (ex vivo) to differentiate them into antigen-presenting cells (APCs). Monocyte-derived APCs (MD-APCs) are then grown in the presence of exogenous target antigens (tumour cell debris, or apoptotic bodies) to become fully mature APCs. (2) Functionality for antigen presentation to T cells of ex vivo MD-APCs is evaluated in vivo. (3) Cellular vaccines are tested in selected rodent animal models. Efficiency and immune response are monitored in pertinent experimental systems for cancer. Pharmacological data are generated for clinical investigation. Tolerance and biologic effects are documented in primates. (4) The first clinical trials on cancer patients are taking place in 1998 on melanoma and prostate cancer to validate the concept. Specialized cell processors with dedicated software and standardized controls are being developed and used for the preparation of cellular vaccines. (5) The evaluation of new non-viral vectors and the validation of new non-viral transfection methods of mononuclear cells with marker genes is in progress and will lead to the ex vivo transfection of genes coding for immunostimulating cytokines or for tumour antigens in MD-APCs. Efficiency will be validated in vitro and in animal models. The ex vivo and animal model studies validate the clinical relevance of this new cellular immunotechnology. Clinical validation of individual autologous cellular vaccines in specific indications for which no treatment is presently available will allow the development of cellular and gene immunotherapy for other types of cancers.

Animals↗