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Biomedical subjects

M Debray-Sachs

Publications and source records attributed to M Debray-Sachs.

At least 19 recordsLinked to original sources
PubMed1991

Prevention of diabetes in NOD mice treated with antibody to murine IFN gamma.

The NOD mouse is studied as an animal model of human insulin-dependent diabetes mellitus (IDDM). To evaluate the role of IFN gamma in the pathogenesis of the disease, we have studied the effect of anti-IFN gamma mAb on the expression of insulitis and clinical diabetes. Treatment of mice with anti-IFN gamma mAb prevented the induction of early IDDM by cyclophosphamide as well as the adoptive transfer of diabetes by spleen cells from diabetic NOD mice. The protection against induction of diabetes by cyclophosphamide was observed in animals treated with the anti-IFN gamma mAb within 24 h following the first cyclophosphamide injection but not in animals in which mAb treatment was started 7 days later. Transfer of disease was prevented both in adult irradiated and in newborn recipients. The absence of clinical signs in these mice was corroborated by a significant reduction of both the extent and severity of insulitis. Over-expression of Ia antigen on endothelial cells lining the islets was also considerably reduced in mice treated with mAb. These data strongly suggest a role for IFN gamma during the autoimmune process leading to beta cell destruction in diabetes and prompt further investigation of the use of such antibodies in the immunoprevention of IDDM.

Animals↗
PubMed1988

Inhibition of insulin release in vitro mediated by mononuclear cells from diabetic patients treated with cyclosporin A or placebo.

Anti-beta-cell-specific cell-mediated immunity was studied over a 12-mo period in 65 recently diagnosed diabetic patients randomly receiving either cyclosporin or placebo. Anti-beta-cell cellular immunity was assessed by an in vitro test based on the inhibition of insulin release from cultured rat islet cells by patients' mononuclear cells. This beta-cell-suppressive effect disappeared in cyclosporin A-treated patients within 1 mo and did not reappear during 12 mo of follow-up. Conversely, the suppressive effect persisted unchanged in placebo-treated patients during 12 mo of follow-up. These changes were predictive neither of cyclosporin A-induced remission nor of relapses. Results of the insulin-release inhibition test were not correlated to islet cell autoantibodies or HLA phenotype.

Adolescent↗
PubMed1988

Cell-mediated immunity to pancreatic islet cells in the non-obese diabetic (NOD) mouse: in vitro characterization and time course study.

The non-obese diabetic (NOD) mouse is an animal model of insulin-dependent diabetes mellitus (IDDM), in which 80% of the females become diabetic after the age of 12 weeks. Using an in vitro assay we investigated the capacity of spleen lymphocytes from NOD mice to inhibit the insulin secretion of normal islet cells after stimulation by theophylline plus arginine. Spleen cells from diabetic NOD mice inhibited the insulin release of DBA/2 islet cells. Depletion experiments using monoclonal antibodies demonstrated that inhibitory cells belonged to the Lyt2 positive T lymphocyte subset. The phenomenon was not restricted by the MHC class I K region, shared by NOD and DBA/2 mice, since lymphocytes from diabetic NOD mice also inhibited the insulin secretion of normal Wistar rat islet cells. Inhibitory T cells were detected in overtly diabetic mice but also in non-diabetic females aged 5-11 weeks indicating that they are not secondary to metabolic disturbances and might contribute to their onset. Conversely they were not found in male NOD mice although some of these mice show insulitis. The presence of these inhibitory T cells might thus represent an early and sensitive marker of anti-islet cell-mediated autoimmunity.

Aging↗
PubMed1987

Effect of cyclosporin A treatment on the production of antibody in insulin-dependent (type I) diabetic patients.

Anti-islet cell and anti-insulin antibody production was studies over a 12-mo period in 82 recently diagnosed diabetics randomly receiving either cyclosporin or placebo. Cyclosporin had only minimal effects on the production of anti-islet cell antibodies whether directed to islet cytoplasmic (immunofluorescence) or membrane (cytotoxicity assay) antigens even in patients undergoing remission. These data suggest that these antibodies do not play a major role in the pathogenesis of the disease particularly since their (irregular) presence is not predictive of the clinical response to cyclosporin. Conversely, cyclosporin completely suppressed the synthesis of antibodies elicited by exogenous insulin irrespective of the insulin doses received, and decreased the autoantibody production against thyroid antigens, indicating that cyclosporin has variable effects on antibody production against various antigens.

Antibody Formation↗
PubMed1986

T-lymphopenia and T-cell imbalance in diabetic db/db mice.

The diabetic db/db mice of the C57 BL/KsJ strain display anti-islet immunity, thymic dysfunction, and lymphopenia. In the present work, lymphocytes, T-cells, and T-cell subsets were enumerated in thymus and spleen from diabetic db/db mice and their db/ + heterozygote littermates from the 10th day to the 10th month of life. A significant lymphopenia was detected in thymus and spleen from the second month on, involving specifically the T-cell compartment, as assessed by use of a monoclonal anti-Thy1 antibody in indirect fluorescence. The study of T-cell subsets by monoclonal anti-Lyt1 and anti-Lyt2 antibodies revealed a significant increase in Lyt1+ cells and a decrease in Lyt2+ cells, with a corresponding increase of the Lyt1+/Lyt2+ ratio. These anomalies appeared early in life, and were apparently linked neither with the degree of hyperglycemia nor with weight loss or infection. The T-cell depletion in thymus was more pronounced in young male (less than 3 mo) than in young female db/db mice. These alterations may correspond to an increase in the helper/suppressor-cytotoxic ratio and could be linked with the thymic anomalies present in these mice, contributing to the development of anti-islet autoimmunity.

Animals↗
PubMed1986

Autoimmune disorders in diabetes.

The development of IDDM correlates with the presence of biologic markers pointing to the involvement of the immune system in the disease process. In addition to clinical observations of association of IDDM with other autoimmune disease and morphologic evidence of a mononuclear cell infiltration of the islets of Langerhans at the onset of the disease, anti-islet cell antibodies are detected in the serum of IDDM patients. Moreover, a strong genetic association with HL-A DR3 and DR4 identifies a genetic background compatible with autoimmune phenomena. Whether autoimmune phenomena are primary or secondary to an initial damage of the islets by infectious agents or other environmental factors is unknown. Whether or not the autoimmune response participates in the selective destruction of insulin-secreting cells has been a major issue in the past five years. The presence of T lymphocytes and anti-islet cell antibodies, which selectively inhibit or lyse insulin-secreting cells in vitro, strongly suggests that it may be the case. A definitive demonstration is difficult to provide in human IDDM. The development of animal models for IDDM has allowed useful insight into the pathogenetic mechanisms responsible for IDDM. In both the BB rat and the low-dose streptozotocin mouse model, the role of the immune system in the destruction of the islets of Langerhans is supported by the prevention of the disease by treatments interfering with the immune system. The BB rat develops a spontaneous autoimmune disease on a genetic background defined by the association with a major histocompatibility complex allele without any evidence for a role in initial damage of islets of a triggering infectious or chemical process. The low-dose streptozotocin model is an autoimmune IDDM secondary to the selective damage of islet cells by a toxin. The present scheme of an islet cell target and specific autoreactive T and B lymphocyte clones raises two major issues: what is the target antigen on islet cells and what is the role at the molecular level of class II major histocompatibility complex genes in susceptibility for IDDM? The first issue is presently being addressed in several laboratories using the hybridoma technology. The second issue is addressed at the biochemical level by studying restriction site polymorphism of major histocompatibility genes in susceptible individuals and IDDM patients, and at the functional level by studying the action of monoclonal antibodies to class II antigen on the development of IDDM in animal models. These steps are likely to be a prerequisite to antigen-specific immunotherapy in IDDM.

Animals↗
PubMed1985

Metabolic and immunological effects of cyclosporin in recently diagnosed type 1 diabetes mellitus.

Cyclosporin 5-10 mg/kg daily was given for 2-8 months to twelve recently diagnosed type 1 diabetics from a mean of 49 +/- SE 14 days after the start of insulin therapy, which was regulated to give near-normal blood glucose and haemoglobin A1c values. Mean insulin dosage dropped from 46 +/- 5 U/day before cyclosporin treatment to 16 +/- 4 U/day by the 7th month. Four patients had a complete remission and the insulin needs of four more were cut by half. The remaining four did not have remissions. Initial basal and glucagon-stimulated C peptide concentrations were higher in those who went into remission than in those who did not; they rose during cyclosporin treatment in the former but not in the latter. OKT4+ lymphocyte functions were suppressed in all patients and OKT4/OKT8 ratios declined. Anti-beta-cell autoimmunity, as indicated by lymphocyte-induced inhibition of insulin release from mouse islet cells, declined in all patients who went into remission. No consistent trend was observed for anti-islet cell antibodies. In forty-four similar, but non-randomised, recently diagnosed diabetics treated with insulin alone, the incidence of remission was 6%.

Adult↗
PubMed1978

[Functional inhibition of isolated pancreatic cells, new technic for the detection of macrophage cytotoxicity].

It is usually accepted that macrophages "activated" by lymphokines may be found cytotoxic against tumoral target cells but show no detectable cytotoxicity in in vitro tests using normal non tumoral cells as target cells. These data have been obtained mainly with the chromium-release test. The present paper describes a new test using normal isolated pancreatic cells as target cells and evaluating the effect of activated or non-activated macrophages on the insulin secretion response to glucose stimulation. The results show a striking decrease in this response following an 18-hr incubation of pancreatic islet cells with activated macrophages, as compared to that of the same cells incubated with control macrophages. This is clear evidence that activated macrophages may alter normal cells and suggests that their cytotoxic properties are not restricted to tumoral target cells.

Animals↗
PubMed1978

[Cytotoxicity of mouse peritoneal cells after alloimmunization].

CBA Mice were immunized by two intraperitoneal injections of 30 X 10(6) DBA/2 or C57BL/6 spleen cells at days--12 and--2. Peritoneal cell population was obtained at day zero by washing the peritoneal cavity of Mice. Adherent cells were then separated using a 2 hrs. incubation in "Falcon" plates followed by washing. This macrophage-rich peritoneal cell population was found nonspecifically cytotoxic against 51Cr labeled tumoral target cells: P815 X DBA/2 mastocytoma cells, EL4 X C57BL/L lymphoma cells and spontaneous lymphoma AKR cells (same H--2k as CBA). This adherent peritoneal cell cytoxicity was demonstrated after 24 hrs. incubation with the target cells. It was found in nonspecific combination as well as when using target cells syngeneic to the donor. These findings suggest that adherent peritoneal cell cytotoxicity could be at least partly due to macrophages and result from factor (s) released by sensitized lymphocytes in vivo in the same way as has been previously demonstrated in vitro.

Animals↗
PubMed1978

Effect of thioglycollate on macrophage lysosomal enzymes.

Mice peritoneal macrophages obtained after i.p. injection of a medium containing thioglycollate (Institut Pasteur, Paris) have increased levels of beta glucuronidase and acid phosphatase, when compared with macrophages obtained without previous thioglycollate injection. The maximum increase is observed between 7 and 10 days after injection and reaches up to 3 to 4 times the normal activity. When using separately the various components of the medium, the same phenomenon may be observed but never to the same degree. The injection of thioglycollate also produces: a) an increase in total number of peritoneal cells, and b) an increase in the percentage of macrophages among these cells. Kinetic studies suggest that thioglycollate injection first induces an increase in the number of peritoneal macrophages and subsequently macrophage modifications resulting in lysosomal enzyme increase.

Acid Phosphatase↗
PubMed1977

[Immune sera, such as antilymphocyte serum, may contain antigen-antibody complexes].

Antilymphocyte sera, either allogeneic or xenogeneic, may retain the antigen used for the immunization of the animal producing the serum in the form of antigen-antibody complexes, at least when the animal is bled within the first two weeks following the last immunizing injection. Evidence for this has been obtained in vivo and in vitro (3). Thus, antilymphocyte injections may contain not only antibodies but the antigens used to prepare the serum as well, and active immunization to these antigens can result in the human or animal recipient. In the heart-allografted rat, pre-transplantation injection of immune complexes prepared from alloantisera prolongs graft survival. The filtrate from these complexes, presumably containing antigens, also prolongs graft survival when administered in conjunction with nonspecific immunosuppresive drugs after transplantation. These results, however, do not allow determination of whether the effect is active or passive, or perhaps both, nor what is the action of the complexes themselves.

Animals↗