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Biomedical subjects

L Pelletier

Publications and source records attributed to L Pelletier.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Renal involvements in human immunodeficiency virus infection].

Two main types of renal disorder may affect the HIV-infected patients. The first type characterized by acute renal failure is not related directly to HIV infection, but results from complications secondary to diagnosis and therapeutic intervention in patients with severe immunodepression. The second type of renal complication includes three quite specific histological renal patterns. The typical "HIV-associated nephropathy" (HIVN), involves essentially the black population, both in Europe (84%) and in North America (83%) and could represent a pathogen-induced disease occurring on a specific genetic background. The two other types of nephropathy, i.e. immune complex-type glomerulonephritis and tubulointerstitial nephritis, involve both black and white seropositive populations and might be the consequence of dysregulation of the immune system.

AIDS-Associated Nephropathy↗
PubMed1994

[Autoimmunity and toxic agents].

In certain subjects medicinal drugs or toxic agents may induce organ-specific or systemic diseases. The mechanisms of this induction vary according to the type of toxic agent involved. The modification of autoantigens by a toxic agent might be the cause of autoimmune disorders. Thus, certain drugs metabolized by enzymes are known to bind on these enzymes in a covalent manner, thereby making the enzyme immunogenic. The immune reaction thus induced could be responsible for hepatitis. If the modified autoantigen is a molecule, such as the class II molecules of the major histocompatibility complex, which plays an important role in communication between the immune system cells, the autoimmune reaction could result in polyclonal lymphocyte B activation and in a lupus-like autoimmune disease. It is also possible that a drug interferes with one of the element which control the advent of autoreactive T cells and in this way becomes responsible for autoimmune systemic manifestations.

Animals↗
PubMed1994

Improvement of TH1 functions during the regulation phase of mercury disease in brown Norway rats.

Brown Norway (BN) rats are poor responders to T-cell mitogens and alloantigens when compared to Lewis (LEW) rats. This is dependent partly upon a defect in IL-2 production. The TH2-mediated immune abnormalities observed in BN rats injected with mercuric chloride (HgCl2) are self-limited and it is probable that this regulation phase involves TH1-like cells. This paper reports on a study of the ability of lymph node cells (LNC) from normal BN and LEW rats and from HgCl2-injected BN rats to produce IL-2 and to proliferate when stimulated in vitro by Con A or alloantigens in mixed lymphocyte reaction (MLR), as well as to develop a cytotoxic T lymphocyte (CTL) response to alloantigens. This study will confirm that LNC from BN rats proliferate less than LNC from LEW rats, that the former produce less IL-2 than the latter, and that the proliferative response is restored partially after addition of IL-2. In addition, it is shown (1) that the CTL response is defective in normal BN rats when compared to that of normal LEW rats, and (2) that, after the second week of HgCl2 injections, the proliferative responses to Con A and alloantigens are improved as well as IL-2 production, and a complete restoration of CTL function is observed. These results show that normal BN rats are deficient in the induction of TH1-like cells and that, from the second week of HgCl2 injections, these TH1 functions improve.

Animals↗
PubMed1993

Autoimmune glomerulonephritis induced by mercury vapour exposure in the Brown Norway rat.

Subcutaneous injections of mercuric chloride induce an autoimmune glomerulonephritis with both granular and linear IgG deposits along the glomerular capillary wall and proteinuria. This disease is due to a T cell dependent polyclonal B cell activation responsible for production of antibodies against self (glomerular basement membrane, immunoglobulins, DNA, myeloperoxydase) and non self (sheep red blood cells, trinitrophenol (TNP)) components. Increase in serum IgE concentration is the hallmark of this disease. To determine if mercury vapours have pathogenic effects is an important problem of public health. The aim of this study was, first to compare the effects of mercury vapour exposure to those of mercury injections and, second, to compare the effects of high doses to those of low doses of mercury. Two exposure levels were studied corresponding to a mercury absorption of 13.1 mumol/week per kg body wt. and 1.7 mumol/week per kg body wt. during a 5-week period. It will be shown that, whereas the mercury concentration in the kidneys was similar in injected--and vapour exposed--rats, the mercury concentration in blood at the end of the exposure was about twice as high in the injected animals. Blood concentration of mercury was related to dose level but kidney content of mercury was similar in all groups, in spite of a dose difference by a factor of seven between low and high exposure. Mercury vapour and HgCl2 injections both trigger autoimmunity to the same extent and, in both cases the extent of autoimmune manifestations was dose-dependent.

Administration, Inhalation↗
PubMed1993

Mercury-induced autoreactive anti-class II T cell line protects from experimental autoimmune encephalomyelitis by the bias of CD8+ antiergotypic cells in Lewis rats.

Brown-Norway (BN) rats injected with HgCl2 develop a systemic autoimmune disease associated with a polyclonal B cell activation, due to autoreactive T cells specific for self-class II molecules, while Lewis (LEW) rats injected with HgCl2 do not exhibit autoimmunity and develop a non-antigen-specific, CD8-mediated immunosuppression assessed by a depression of T cell functions, and a protection against experimental autoimmune encephalomyelitis (EAE). Resistance to HgCl2-induced autoimmunity is not due to these suppressor cells since treatment with an anti-CD8 monoclonal antibody (mAb) did not allow autoimmunity to appear. The absence of autoimmunity in this strain could result from the absence of autoreactive T cells, or from quantitative or qualitative differences of these cells between susceptible and resistant strains. In the present study, we show that CD4+ anti-class II T cells are present in HgCl2-injected LEW rats and are as frequent as in BN rats when assessed by limiting dilution analysis. LEW CD4+ autoreactive T cell lines were derived. They proliferated in the presence of normal class II-bearing cells, secreted interleukin 2, and did not induce B cells to produce immunoglobulins. Transfer of one of these lines, LEW Hg A, into normal LEW rats led to the appearance of CD8+ cells responsible for a non-antigen-specific immunosuppression that induced complete protection from EAE. Immunosuppression was abrogated after treatment with an anti-CD8 mAb. In vitro, CD8+ cells from rats injected with the LEW Hg A T cell line proliferated in the presence of activated T cells whatever their origin. We conclude that HgCl2 induces CD4+ autoreactive T cells that proliferate in the presence of class II+ cells in susceptible BN as well as in resistant LEW rats. But while these cells collaborate with B cells to produce autoantibodies in BN rats, they initiate in LEW rats a suppressor circuit involving antiergotypic CD8+ suppressor cells.

Animals↗
PubMed1993

[Cytokines and immune response].

This review paper briefly describes the principal cytokines involved in immune response, and in particular their role in some of its key-steps: antigen presentation; activation, proliferation and differentiation of CD4+ T cell subsets; antibody response by B cells; manifestations of hypersensitivity. The role played by cytokines in cytotoxic T cell (CTL) differentiation and in T cell-mediated suppression phenomena is also discussed. It seems that the auxiliary CD4+ memory cells secrete either IL-2 and interferon gamma (Th1) or IL-4 and IL-5 (Th2). It has recently been suggested that cytotoxic/suppressor CD8+ cells can also be divided into cells that secrete interferon gamma and no IL-4 (CTL) and cells that secrete IL-4 and IL-5 (suppressor T cells). The reciprocal regulatory effects of these cell populations through these interleukins is also discussed.

Animals↗
PubMed1993

Anti-renin T cells trigger normal B cells to produce anti-renin antibodies and normalize blood pressure in spontaneously hypertensive rats.

Spontaneously hypertensive (SH) rats immunized with mouse renin produce anti-renin antibodies, responsible for down-modulation of blood pressure, associated with an infiltration of kidneys by mononuclear cells. In this work, anti-renin T cells from SH rats immunized with renin have been stimulated in vitro, and we have studied in vitro and in vivo their effect on anti-renin antibody production by normal syngeneic B cells. We show that, in vitro, renin-activated T cells induce a renin-specific antibody response without addition of exogenous renin. Anti-renin T cells injected into naive SH rats trigger normal B cells to secrete high amounts of monospecific anti-renin IgG antibodies as early as day 5. These antibodies interfere with the homeostasis of the renin-angiotensin system leading to the normalization of blood pressure without any nephritis. These results show that anti-renin B cells are either not tolerant per se or in a reversible state of anergy. Our results also suggest that anti-renin B cells constitutively express renin-derived peptides in such a way that they may be stimulated by activated anti-renin T cells; these cells express IL-4 mRNA indicating that IL-4 could play a role in the differentiation of B cells.

Animals↗
PubMed1993

Evidence for a role of antilaminin-producing B cell clones that escape tolerance in the pathogenesis of HgCl2-induced membranous glomerulopathy.

In Brown-Norway rats HgCl2 induces an autoimmune disease due to a T-dependent B cell polyclonal activation. This disease is marked by the production of numerous antibodies including antiglomerular basement membrane (GBM) antibodies. Rats exhibit a biphasic glomerulopathy with heavy proteinuria. Initially anti-GBM antibodies are found linearly deposited; they precede the appearance of membranous glomerulopathy. Rats recover spontaneously even if HgCl2 injections are pursued, but mechanisms at play are unclear. We have assessed the effects of transplanting the spleen from a BN rat, either at the acme of the disease or at the time of convalescence, into naive BN rats, some of which were then injected with HgCl2. Transplantation of a spleen from HgCl2-injected rats at the acme of the disease dramatically protects BN rats from all the manifestations of the mercury disease. BN rats transplanted with a spleen from HgCl2-injected rats at the time of convalescence only exhibited a typical membranous glomerulopathy with heavy proteinuria but without circulating anti-GBM antibodies. Antilaminin antibodies were eluted from the glomeruli. This study shows that spleen cells from HgCl2-injected rats are able to confer tolerance to HgCl2-induced autoimmunity. It also shows that some B cell clones escape this tolerance. Finally, this study strongly suggests that membranous glomerulopathy, responsible for proteinuria in this model, is related to the presence of antilaminin antibodies.

Animals↗
PubMed1993

Efficacy of ifosfamide in combination with doxorubicin for the treatment of metastatic soft-tissue sarcoma. The Eastern Cooperative Oncology Group.

On the basis of ifosfamide's demonstrated single-agent activity in adult soft-tissue sarcoma, the Eastern Cooperative Oncology Group (ECOG) tested whether ifosfamide would add to the efficacy of doxorubicin in a three-regimen, controlled phase III trial. Doxorubicin, ECOG's standard to which newer chemotherapeutic treatments are compared, was given at a dose of 80 mg/m2 every 3 weeks and was designated the control regimen. Ifosfamide was given at a dose of 3,750 mg/m2 on days 1 and 2 every 3 weeks in combination with 30 mg/m2 doxorubicin given each day for 2 days; additionally, mesna was given to counter the genitourinary toxicity associated with ifosfamide. A second experimental regimen consisted of doxorubicin (40 mg/m2), mitomycin (8 mg/m2), and cisplatin (60 mg/m2), all given intravenously on day 1, with repeated cycles being scheduled for day 21. Of the 279 adults with soft-tissue sarcoma who were entered in the study, 260 were analyzed. The overall response rate was 20% for doxorubicin, 34% for ifosfamide/doxorubicin, and 31% for doxorubicin/mitomycin/cisplatin, with the difference between the first two regimens being significant (P = 0.04). The median survival was 8.8, 11.5, and 9 months, respectively, for the three regimens. Myelosuppression, the predominant toxicity, occurred in 60%, 88%, and 58% of patients, respectively.

Adult↗
PubMed1992

[Compliance with treatment in diabetic adolescents].

The study of compliance with therapy among teenagers with diabetes mellitus is a challenging task. Although several studies have addressed this problem, available knowledge in this field remains scant and the lack of understanding of factors which determine compliance with therapy hinders the development of interventions capable of helping diabetic teenagers to improve their quality of life. On the basis of a review of the relevant literature, this paper discusses compliance with therapy in the light of the specific features of teenage development. The two main theoretical models used to explain compliance with therapy in adolescent diabetics are presented. Parameters of compliance with therapy and the methods used to measure these parameters are also discussed.

Adolescent↗
PubMed1991

HgCl2-induced perturbation of the T cell network in experimental allergic encephalomyelitis. I. In vitro characterization of T cells involved.

Mercuric chloride (HgCl2) induces in Lewis (LEW) rats a non-antigen-specific immunosuppression and is able to down-modulate experimental allergic encephalomyelitis in about 70% of the rats. The aim of the present study was to determine the frequencies of lymph node cells involved in the proliferative response to myelin basic protein in rats injected with HgCl2 and immunized with myelin by using limiting dilution analysis (LDA). Highly frequent CD8+ T suppressor cells and at least 10-fold less frequent protein basic-specific T helper cells were detected in these rats. A third cell type allowing the proliferative response of Th cells in spite of Ts cells was also demonstrated. These cells, which could act as contrasuppressor cells, were CD4+ and adhered to Vicia villosa lectin; their frequency was in the same range as that of T helper cells. These data illustrate the potential role of different levels of T cell immunoregulatory activity in autoimmunity and the major interest of LDA in their analysis.

Animals↗
PubMed1991

HgCl2-induced perturbation of the T cell network in experimental allergic encephalomyelitis. II. In vivo demonstration of the role of T suppressor and contrasuppressor cells.

In the companion paper (J. Rossert et al., Cell. Immunol. 137, 1991), we showed by using limiting dilution analysis that Lewis (LEW) rats injected with HgCl2 and immunized with myelin (LEWHg/MYE) exhibit anti-basic protein CD4+ T helper cells (Th), at least 10-fold more frequent CD8+ T suppressor cells (Ts), and T contrasuppressor cells (Tcs). These Tcs cells were shown to be CD4+ T cells adhering to Vicia villosa (VV) lectin and allowed Th cells to proliferate despite the presence of Ts cells. The CD8+ Ts cells might be responsible for the protection from experimental allergic encephalomyelitis (EAE) observed in about 70% of LEW rats injected with HgCl2. The concomitant presence of CD4+ Tcs cells might explain that 30% of the rats escaped this protection. The aim of this work is to demonstrate in vivo the roles of CD8+ Ts cells and Tcs cells in mercury-induced protection from EAE. It will be shown that LEWHg/MYE rats depleted of CD8+ cells as well as LEWHg/MYE rats transferred with VV lectin-adherent Tcs cells develop EAE. These data demonstrate that CD8+ Ts cells are responsible for HgCl2-induced protection and that Tcs cells are involved in the control of Ts cells in vivo.

Animals↗
PubMed1991

[Manifestation of immunologic origin produced by toxic compounds].

Toxic agents may induce immunological manifestations by interfering with either non specific or specific pathways of immunity. The interference with the specific pathways may result in stimulatory (autoimmunity or hypersensitivity) or suppressive reactions. Mechanisms responsible for autoimmunity of hypersensitivity are now better understood. Hypersensitive reaction may be the consequence of the recognition by T cells of the xenobiotic presented by MHC class II molecules. Mechanisms leading to autoimmune reaction probably differ according to the nature of the drug. Thus drugs metabolized by liver enzymes could induce autoimmune hepatitis as a consequence of the binding of a reactive metabolite to the enzyme, thus rendered immunogenic. Other drugs like thiol or metal-containing chemicals could be responsible for autoimmunity reaction by interacting with molecules involved in T-B lymphocyte cooperation. The knowledge of the involved mechanisms should allow to develop predictive assays.

Allergens↗
PubMed1991

Effect of the thiol group on experimental gold-induced autoimmunity.

Brown Norway rats injected with aurothiopropanolsulfonate sodium salt develop systemic autoimmunity. The aim of this study was to assess the influence of the sulfur-containing group in this experimental model of gold-induced autoimmunity. It was shown that the sulfur-containing group does not induce autoimmunity of itself, but potentiates the immunotoxic effects of gold.

Animals↗
PubMed1991

Experimental gold-induced autoimmunity.

The pathogenesis of gold-induced autoimmunity and membranous glomerulopathy is not well understood. HgCl2 and D-penicillamine, other chemicals known to trigger membranous glomerulopathy in humans, induce autoimmune manifestations in Brown-Norway (BN) rats but not in Lewis (LEW) rats. These chemicals trigger T-cell clones which are specific for self class II molecules from the major histocompatibility complex and are probably responsible for the polyclonal B-cell activation observed. The aim of this work was to test the effects of aurothiopropanolsulphonate (ATPS) in BN and LEW rats. In BN rats, ATPS induced a polyclonal B-cell activation marked by lymphoproliferation, hyperimmunoglobulinaemia affecting mainly IgE, and by the production of numerous autoantibodies. A glomerulonephritis occurred, initially due to anti-glomerular basement membrane antibody deposition, and later to the formation of granular deposits, occasionally resulting in a typical membranous glomerulopathy. Self class-II-specific T-cells were found that might be responsible for the polyclonal B-cell activation. Lewis rats were free of glomerulopathy but, like BN rats, exhibited an interstitial nephritis and some degree of polyclonal B-cell activation. These findings demonstrate that, depending on the strain, ATPS triggers different B-cell clones inducing different degrees of autoimmunity.

Animals↗
PubMed1991

Thymic epithelial cell transplantation in patients with acquired immunodeficiency syndrome. Evidence for infection by HIV-I of newly differentiated T cells at the site of transplantation.

From October 1983 to July 1984, 11 adult AIDS patients have received single or repeated thymic grafts. All have had opportunistic infections and 3 also had Kaposi's sarcoma. Thymic tissue from infants undergoing cardiac surgery was cultured to provide a thymocyte- and fibroblast-free epithelial cell inoculum. 18-21 days post-explantation, cells and explants were injected intraperitoneally, intramuscularly or intrahepatically. Transplants were well tolerated in all cases. In 7 cases liver biopsy was performed at the time of grafting and 2 months later. Ten patients have died after a mean survival time following transplantation of 8.7 months while 1 patient was lost to follow up. Clinical improvement and absence of new opportunistic infections were apparent for 4 months following transplantation. Partial immunoreconstitution was evidenced by an increase in peripheral blood lymphocytes (8 of 10 cases) and lymphocyte subsets (7 of 10 cases) as well as by presence of T4 and T8 positive cells in the liver (5 of 7 cases). In 5 of 7 patients, double-staining immunofluorescence showed that HIV-I antigens were present in T4-phenotype cells, at the site of the graft, 2 months after grafting, but were not detected in the liver at the time of grafting. Transient immunoreconstitution, therefore, maybe related to destruction of newly differentiated T lymphocytes.

Acquired Immunodeficiency Syndrome↗