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C Carnaud

Publications and source records attributed to C Carnaud.

At least 37 records · Page 2Linked to original sources
PubMed1995

Molecular analysis of TCR junctional variability in individual infiltrated islets of non-obese diabetic mice: evidence for the constitution of largely autonomous T cell foci within the same pancreas.

Insulitis develops in non-obese diabetic (NOD) mice as a multicentric and asynchronous process. In an effort to understand how this T cell mediated process expands within each islet and propagates between the islets of the same pancreas, we have analyzed the junctional diversity of TCR V beta 6 and V beta 8.2 transcripts cloned from infiltrated islets. The material examined was obtained from individual islets of 8 and 12 week old NOD mice or from pooled islets of 4 week old individual mice. Compared with spleen transcripts, where every V beta 6 or V beta 8.2 clone displays a different junction, islet transcripts are considerably less diverse. Each islet harbors from one to a maximum of six independent CDR3 sequences out of 10 or more analyzed colonies. On the other hand, there is an overall diversity of sequences when comparing the islets of the same pancreas or individual mice at 4 weeks. Altogether, these results support the idea that TCR repertoires are already divergent at the very early onset of insulitis and that each islet-centered infiltrate develops rather autonomously from the oligoclonal expansion of a limited set of precursors. Recirculation between islets is limited and does not seem to be the main mode of propagation of insulitis. Finally, a close analysis of J beta usage and N additions in beta chain transcripts from infiltrating cells reveals definite biases suggestive of an ongoing selective process imposed upon intra-pancreatic T lymphocytes.

Amino Acid Sequence↗
PubMed1995

Accelerated beta-cell destruction in adoptively transferred autoimmune diabetes correlates with an increased expression of the genes coding for TNF-alpha and granzyme A in the intra-islet infiltrates.

Autoimmune destruction of beta-cells in nonobese diabetic (NOD) mice is greatly accelerated by adoptive cotransfer of syngeneic CD4+ and CD8+ T-cells from diabetic animals into newborn NOD mice. We followed, by in situ hybridization, the appearance of mRNA of the tumor necrosis factor (TNF)-alpha gene and, as a marker for activated cytotoxic T-cells, of the serine protease granzyme A gene in the cellular infiltrates generated by cell transfer at birth. Cells expressing the genes for granzyme A or TNF-alpha were seen in considerable numbers already on day 14, after adoptive transfer. These numbers gradually increased in the intra-islet infiltrates from day 14 through day 30 after adoptive transfer. Compared with our previous findings in NOD mice developing spontaneous insulin-dependent diabetes mellitus (IDDM) (Held W, MacDonald HR, Weissman IL, Hess MW, Mueller C: Genes encoding tumor necrosis factor alpha and granzyme A are expressed during development of autoimmune diabetes. Proc Natl Acad Sci USA 87:2239-2243, 1990), frequencies of cells with TNF-alpha and granzyme A mRNA were 2- and 12-fold higher, respectively, in transferred IDDM (trIDDM). TNF-alpha mRNA positive cells were predominantly found in the CD4+ T-cell subset of the pancreas-infiltrating cells, whereas granzyme A mRNA positive cells were mainly observed in the CD4- T-cell subset. The effects of the observed enhanced TNF expression upon the pathogenesis of trIDDM are as yet unknown.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The contribution of animal models to the understanding of the pathogenesis of type 1 diabetes.

The autoimmune nature of insulin-dependent diabetes mellitus (type 1 diabetes) has been definitively established during the past ten years only, owing essentially to the development of the NOD and the BB rat models. Three of the four criterias required for defining an autoimmune disease have been demonstrated in these animal models. IDDM is accompanied by immunological stigmatas including circulating autoantibodies and insulitis (lymphocytic infiltration of the islets of Langerhans), it is attenuated or prevented by immunosuppressors and it is transferable from diabetic to non-diabetic mice or rats, via T lymphocytes. Only the fourth criterium, namely the induction of the disease by immunization with an autoantigen, has so far not been met. As is the case for many, if not most, autoimmune diseases, the pathogenesis of IDDM is, however, far from being totally understood. Many aspects including the circumstances favoring escape from self-tolerance, the role of the genetic background, the nature of the pancreatic antigens involved in the initiation and perpetuation of the disease, the effector mechanisms responsible for the elimination of the insulin cells and, most importantly, the conditions for restoring tolerance are at the forefront of immunopathologists' concerns. We provide in this review an account of the present situation in these different areas of research. There is no doubt that a cure or a prevention of the disease will be available in the forseeable future. Experiments on animal models have already initiated several clinical trials and epidemiological studies, and this is probably only the beginning of a long list.

Animals↗
PubMed1994

[Cell cooperation in immune responses].

All immune responses are assisted by different subpopulations of cells with complementary properties. Beside T and B lymphocytes specialized into effector killers, pro-inflammatory or antibody-producing cells, there are accessory and helper cells which exert various functions, such as antigen degradation and presentation, activating signal amplification and support of antigen-activated lymphocytic clones expansion and their functional differentiation. These cells, whose role is to co-operate with effector lymphocytes, are either lymphocytes, such as antigen-presenting B cells and helper T cells, or cells of haematopoietic origin belonging to the monocytic lineage, such as macrophages, monocytes and dendritic cells. Co-operation between subpopulations of the immune system takes place either by cell-to-cell interactions, or by indirect interactions via soluble mediators. Direct interactions postulate the involvement of receptor molecules and ligand-molecules expressed at cell surface. Indirect interactions are mediated by cytokines secreted by accessory or helper cells and acting at short distance to the point of secretion. Surface molecules and cytokines are well characterized both biochemically and functionally, and we are now in a position to manipulate the essential stages of cellular or hormonal immune response by using either cytokines and their inhibitors, or agonists or antagonists of surface receptors. Co-operation between cells participates in the autoregulation of the immune system. Through modulation of surface molecules and synthesis of cytokines the immune system can amplify discreet signals or repress untimely responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Communication↗
PubMed1994

Anchored polymerase chain reaction based analysis of the V beta repertoire in the non-obese diabetic (NOD) mouse.

We have performed extensive analyses of T cell receptor V beta usage in the thymus, the spleen and the infiltrated islets of preclinical non-obese diabetic (NOD) mice. A semiquantitative anchored polymerase chain reaction (An-PCR) protocol has been developed for this purpose. The validity of the method has been first assessed by antibody staining with a panel of anti-V beta monoclonal antibodies (mAb). The results obtained by An-PCR are accurate, reproducible, and in good agreement with cell surface protein staining. A strict comparison between thymus and spleen repertoires reveals no major V beta-specific deletion except the already reported V beta 3 deletion due to Mtv-3. Certain V beta such as V beta 15, 18, 20 are found with a low frequency in the spleen, but the fact that they are also scarce in the thymus probably reflects a poor availability of these genetic elements during beta chain rearrangement rather than negative selection. Other V beta, such as V beta 2, V beta 12 and V beta 14 are significantly more abundant in the spleen than in the thymus. This finding was confirmed by mAb staining for V beta 2 and V beta 14. The expansion asymmetrically affects the CD4+ subset and can be traced back to the mature, single-positive thymocyte subset, suggesting an intrathymic positive selection event. V beta repertoires in infiltrated islets of 13- and 18-week-old, non-diabetic mice are polymorphic. Practically all the V beta found in the peripheral lymphoid tissues are present in the islets, in similar proportions. The major exception is V beta 12, one of the V beta which is subject to expansion during intrathymic differentiation and which is further augmented in the islets, both at 13 and 18 weeks. This increase probably reflects further peripheral amplification of the V beta 12-bearing subset due to encounter with the same ligand as in the thymus or with a cross-reactive motif. Finally, the nucleotide sequencing of all the V beta segments in usage in the NOD strain confirms the absence of allelic polymorphism of V beta-coding regions.

Animals↗
PubMed1993

Evidence for a preferential V beta usage by the T cells which adoptively transfer diabetes in NOD mice.

Non-obese diabetic (NOD) mice become spontaneously diabetic as a result of a genetically programmed autoimmune process mediated by autoreactive T lymphocytes and directed against beta cell antigen(s). Studies dealing with T cell receptor (TcR) variable (V) gene usage by such autoreactive T lymphocytes have given contrasted results. Various reasons may explain these discrepancies: the multiplicity of antigenic epitopes putatively recognized by T cells, the ambiguity between specifically committed T cells and passenger lymphocytes homing randomly to the pancreas, the necessarily limited size of the T cell clone panels which have been analyzed for TcR rearrangements and, last but not least, the flexibility of T cell repertoires. To circumvent some of these difficulties, we have decided to concentrate upon the T cell population present in diseased animals and capable of transferring diabetes into young naive NOD recipients. This population, composed of CD4+ and CD8+ T cells, is presumably committed against the relevant beta cell antigens and is the most likely to reveal a bias in V gene usage if such a bias does indeed exist. To find out whether certain V beta genes are more frequently used than others by such pathogenic T cells, T lymphocytes from diabetic donors have been depleted in vitro of defined V beta subsets before being reinoculated into permissive recipients. Out of four V beta families probed under such conditions, three (V beta 8, V beta 5 and V beta 11) are neutral. Their absence neither increases nor reduces the final incidence of successful transfers, indicating that these gene segments are not preferentially used. In contrast, the depletion of V beta 6-positive T cells results in a severe reduction of transfers, suggesting that V beta 6 gene is used with a relatively high frequency by diabetogenic CD4+ and/or CD8+ T cells. To define more precisely which subset uses V beta 6 gene preferentially, we have performed mixing experiments with deleted and intact subsets. The results, based on disease transfer and insulitis severity, indicate that the V beta 6 bias affects predominantly the CD4+ subset. Thus, at variance with several studies concluding that V gene usage in NOD mice is heterogeneous, our present data suggest that disease transferring T cells use a relatively restricted set of V beta genes.

Animals↗
PubMed1993

Establishment of T-cell lines from infiltrated NOD islets by stimulation of specific T-cell receptor V beta segments.

The aims of this study were firstly to establish permanent T-cell lines from infiltrated NOD islets, by repeated stimulation of the antigen T-cell receptor with anti-V beta monoclonal antibodies (mAb) and, secondly, to characterize some of their cytotoxic and pathogenic properties. The use of anti-V beta antibodies was aimed at driving the expansion of the T cells in the absence of pancreatic antigen and, at the same time, at selecting lymphocytes expressing a given V beta gene product as an element of their TCR. Twelve lines were established as long-term cultures by regular stimulation with plastic-bound anti-V beta 6 or anti-V beta 8 mAb. The eight lines cultured with anti-V beta 6 mAb were phenotyped as early as one month after initiation and were all V beta 6+/V beta 8-. Three were CD8+ and five CD4+. Of the four lines established with anti-V beta 8 mAb, three were V beta 8+/V beta 6- and one (FD) was unexpectedly phenotyped as V beta 6+/V beta 8-. Clones derived from the FD line confirmed the expression of V beta 6. The cell-mediated cytolytic properties of the 12 lines were evaluated in two independent assays: an antibody-redirected assay to measure the lytic potential irrespective of antigen specificity and a direct cytolytic assay on YAC cells for assessing NK-like activity. The results indicate that practically all the lines (11 out of 12), irrespective of their CD4/CD8 phenotype or V beta expression, can exert cell-mediated cytotoxicity when their TCR/CD3 complex is linked to a target cell. On the other hand, anti-YAC activity is almost exclusively confined to CD8+ cell lines. Pathogenicity was evaluated in two CD4+ T cell lines, one which showed cytolytic activity in the redirected assay but not in the YAC assay (FD) and one which was totally devoid of cytotoxic activity (AH). The two lines were injected into newborn NOD mice with or without CD8+ polyclonal T cells. The results indicate that FD, the cytotoxic line, can induce severe lesions of insulitis when coinjected with polyclonal CD8+ T cells. In contrast, AH, the non-cytotoxic line, injected under the same conditions, induces no lesions. Altogether, the present data demonstrate the feasibility of establishing permanent T-cell lines on the basis of V beta expression.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Cellular basis of T-cell autoreactivity in autoimmune diseases.

There is no doubt that T cells play a key role in the pathogenesis of autoimmune diseases (AD) both as effector and regulatory cells. Despite spectacular progress in the understanding of natural tolerance to self, owing particularly to transgenic technology, important questions remain open regarding the pathogenesis of AD, the conditions favoring the transition from benign or 'physiological' autoimmunity to deleterious autoimmunity, and the precise effector mechanisms. This review on the cellular basis of T-cell-mediated AD begins with an enumeration of the main arguments in favor of direct T-cell involvement, special emphasis being given to two animal models which have been most extensively investigated: experimental allergic encephalomyelitis, and the nonobese diabetic mouse. The question as to whether pathogenic T cells use a restricted repertoire of V beta genes is examined in the context of these two models. From here we proceed to an evaluation of the mechanisms of onset of AD, discussing both extrinsic and intrinsic factors responsible for the breakdown in T-cell tolerance and reviewing the arguments in favor of suppressor T cells being actively involved in the prevention of autoimmunity. The last two sections are devoted to the effector mechanisms responsible for tissue injury in organ-specific AD and to T-cell-directed therapeutic interventions, respectively. We discuss the two main pathogenic hypotheses based on direct intervention of cytotoxic T cells or indirect involvement of inflammatory cytokines and macrophages, and evaluate the importance of ecotaxis in leading autoreactive T cells to the site of injury. We conclude on a brief and nonexhaustive list of strategies aimed at selectively neutralizing potentially harmful T cells.

Animals↗
PubMed1993

Characterization of the extracellular matrix-containing giant perivascular spaces in the NOD mouse thymus.

It is well established that the NOD mouse develops T-cell-dependent autoimmune type I diabetes that is abolished by neonatal Tx and enhanced by Tx at weaning. In a previous study, we demonstrated that the NOD thymus displays various abnormalities in the microenvironmental compartment, including abnormal distribution of epithelial cell subsets, precocious decline in thymic hormone production and formation of giant PVS. These latter structures present an internal ECM-containing network filled with T-cells and to a lesser extent B-cells. Herein we have investigated further the giant PVS and particularly the origin of the T-cells that colonize these structures. The thymic origin of intra-PVS T-cells was ascertained by distinct protocols. First, sublethal X-ray irradiation or HC treatment leading to cortical thymocyte depletion showed that intra-PVS lymphocytes were resistant, similar to medullary thymocytes. Second, adoptive transfer experiments that used newborn or adult irradiated Thy-1 congenic recipients demonstrated that intra-PVS accumulation of T-cells did not result from the reentry of peripheral mature T-cells into the thymus. Third, kinetic studies that used BrdUrd pulse chase revealed that labeled intra-PVS cells appear late, simultaneously with medullary thymocytes, and remain only transiently within the PVS. Thus, the kinetics of T-cell reconstitution of PVS was compatible with the progressive differentiation of T-cell precursors originating from the thymic cortex. In this respect, the giant PVS of the NOD mouse thymus may represent a useful model to study the relationships between trafficking thymocytes and ECM proteins.

Animals↗
PubMed1993

Resistance of NOD mice to salmonellosis.

The NOD mouse strain has become one of the most popular animal models for exploring insulin dependent type 1 diabetes. Genetic studies have underlined the polygenic nature of the murine disease. Two such genes were mapped on chromosome 1. One, associated with diabetes onset, is strongly linked with the Lsh, Ity, bcg genes encoding for resistance against L. donovani, S. typhimurium and Mycobacterium. We have undertaken to phenotype NOD mice with regard to one of these resistance genes. After infection with Salmonella abortusovis, we found that NOD mice bore the resistant phenotype/Ityr, which is responsible for early resistance against Salmonella infection.

Animals↗
PubMed1992

Acquired allo-tolerance to major or minor histocompatibility antigens indifferently contributes to preventing diabetes development in non-obese diabetic (NOD) mice.

Diabetes in NOD mice represents the end stage of a genetically-programmed autoimmune process mediated by T lymphocytes and directed against insulin-producing beta cells. We have shown in a previous study that the course of the disease is significantly inhibited in NOD mice which have been made tolerant at birth to foreign histocompatibility antigens. This early T cell manipulation results in a significant delay of disease onset, reduced overall incidence and less severe alterations of islet cells. In order to characterize better the nature of the foreign tolerogenic determinants responsible for this protection, we have now examined separately the contribution of MHC and non-MHC antigens. Two lines of congenic mice were used as donors of tolerogenic cells, NOD.H-2b, which differ from NOD by the MHC-encoded antigens only, and B10.H-2g7, which differ by all the minor histocompatibility antigens encoded by the B10 background, but which share with NOD mice the same MHC haplotype. Our results show that NOD recipients of F1 semi-compatible cells become specifically tolerant to the set of alloantigens to which they were neonatally exposed. Unresponsiveness, assessed by lack of CTL generation, is profound and specific. Yet, despite the fact that distinct sets of alloreactive T cell precursors are silenced, mice made tolerant indifferently to major or minor histocompatibility antigens are significantly protected against overt diabetes. These results could mean that each set of MHC and non-MHC encoded determinants can independently cross-tolerize a sufficient proportion of the autoreactive repertoire to slow the natural course of the disease. Alternatively, neonatally-acquired tolerance might induce polyclonal activation of the immune system resulting in the suppression or the immunodeviation of potentially harmful, autoreactive T cell clones.

Animals↗
PubMed1991

Host humoral and cellular immune mechanisms in the continued suppression of Friend erythroleukemia metastases after interferon alpha/beta treatment in mice.

DBA/2 mice were injected intravenously with 2 x 10(6) 3C18 Friend erythroleukemia cells (FLC), a cell line resistant to interferon alpha/beta (IFN-alpha/beta). Although daily administration of mouse IFN-alpha/beta markedly increased the mean survival time, most IFN-treated mice continued to harbor FLC in different organs. To investigate the mechanisms responsible for this persistent suppression of FLC growth in IFN-treated mice, we undertook a series of adoptive transfer experiments with sera and spleen cells. Sera from FLC-injected, IFN-treated mice were very effective in conferring protection on DBA/2 mice even when injected systemically (intravenously) 18-24 h before intravenous challenge with FLC. These sera also exhibited antitumor activity when injected subcutaneously or intraperitoneally together with FLC. The protective factor in serum was shown to be an immunoglobulin. FLC-injected, IFN-treated mice developed antibodies to FLC demonstrable by radioimmunoassay and complement-dependent cytotoxicity. Sera from these mice recognized a specific 65-kD FLC membrane antigen(s) not detectable on membrane extracts from RBL-5 or ESb tumor cells, or on normal spleen cells. FLC-injected, IFN-treated mice also developed a specific cellular response demonstrable by transfer of protection with spleen cells injected intravenously or subcutaneously. Analysis of the responsible spleen cell populations indicated that the effector cells were neither T nor B cells. These results demonstrating the importance of host humoral and cellular immune mechanisms in the persistent suppression of FLC in IFN-treated mice may be relevant to the use of IFN-alpha/beta in patients in whom tumors may regress and tumor cells may then remain latent for extended periods of time.

Animals↗
PubMed1991

CD8+ T cell homing to the pancreas in the nonobese diabetic mouse is CD4+ T cell-dependent.

The adoptive transfer of type I diabetes in nonobese diabetic mice requires the contribution of both CD4+ and CD8+ T cells. To further elucidate the cellular pathway(s) of beta-cell destruction and the responsibility of each subset, high doses of committed T cells from diabetic mice purified to single subsets, were injected into syngeneic nonobese diabetic neonates. The recipients of single or mixed subsets were followed for clinical manifestations of diabetes and examined at 30 days of age for in situ lesions. None of the animals injected with either CD4+ or CD8+ T cells became overtly diabetic during the 30 days of observation whereas 8 of 23 mice inoculated with a mixture of the two subsets developed glycosuria and hyperglycemia. However, insulitis was found in 6 of the 13 mice injected with CD4+ T cells whereas only 1 of the 9 mice injected with CD8+ T cells showed marginal infiltration of the pancreas. The lesions initiated by CD4+ T cells alone were considerably less severe than those induced by the mixture of both subsets, corroborating the fact that overt disease did not occur in the former group. Together, these results suggest a distinct function for each diabetogenic T cell subset. CD4+ T cells, which have the capacity to home to the pancreas, promote in turn the influx of CD8+ effector T cells that do not by themselves accumulate in this organ. These results illustrate a novel form of T-T cell interactions leading to organ specific autoimmune lesions.

Animals↗
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↗
PubMed1990

Anti-tumor effects of interferon in mice injected with interferon-sensitive and interferon-resistant Friend erythroleukemia cells. VIII. Role of the immune system in the inhibition of visceral metastases.

DBA/2 mice were injected i.v. with IFN alpha/beta-resistant 3CI8 Friend erythroleukemia cells (FLC) which metastasize to the liver and spleen. IFN alpha/beta treatment of FLC-injected mice increased their survival time and these mice developed a resistance to a second challenge with FLC. The efficacy of IFN alpha/beta in increasing the survival time was compared between normal immunocompetent and immunodeficient mice. The anti-tumor action of IFN was markedly reduced or abolished in newborn DBA/2 mice, in adult athymic nu/nu and beige DBA/2 mice, and in BALB/c scid/scid mice. To determine the phenotype of the effector cells involved, FLC-injected DBA/2 mice were treated with antibodies to asialo-GMI, CD4, or CD8 antigens, or with cyclosporin A or silica. IFN alpha/beta treatment proved much less effective in these mice, indicating that a variety of effector cell types participated in the IFN-induced suppression of visceral metastases. Thus, an intact immune system appears to be essential to obtain optimal therapeutic effects of IFN alpha/beta in this experimental model.

Animals↗
PubMed1990

The nonobese diabetic mouse model. Independent expression of humoral and cell-mediated autoimmune features.

Nonobese diabetic (NOD) mice present concomitant signs of cell-mediated and humoral autoimmunity. Whereas the involvement of the cell-mediated manifestations in the pathogenesis of diabetes has been clearly demonstrated, the origin and the relevance of the humoral manifestations is still unclear. In the present study, we have tried to determine whether the humoral manifestations observed in NOD mice were secondary to the cell-mediated antiislet reaction, or whether they resulted from an autonomous polyclonal activation of B cells, a possibility suggested by the notorious presence of antilymphocyte antibodies with thymocytotoxic properties, in the serum of old NOD females. To discriminate between the two alternatives, we have followed the titers of thymocytotoxic autoantibodies in aging males and females, as well as in F1 hybrids where the organ-specific disease is recessive, and in back-crossed mice where the susceptibility genes responsible for insulitis and diabetes have segregated. In addition to thymocytotoxic antibodies, we have also screened the sera of these animals for hyperglobulinemia, antiinsulin, and anti-DNA autoantibodies that are classically associated with polyclonal B cell activation in autoimmune strains of mice. The results indicate that these humoral anomalies are clearly disconnected from the occurrence of diabetes and even of insulitis. Lymphocytotoxic antibodies appear several weeks after the onset of insulitis in NOD mice, are not correlated with disease occurrence and have no predictive value for its onset. The humoral manifestations that include, beside thymocytotoxic antibodies, antiinsulin antibodies, hyperglobulinemia, but no anti-DNA antibodies, are found at the same frequency in F1 mice as in parental mice in spite of the fact that the former are practically free of insulitis lesions. These anomalies are also randomly distributed among back-crossed mice independently of the presence and the severity of the organ-specific lesions. Altogether, these results suggest that NOD mice, like other autoimmune strains, suffer from a genetically inherited defect of B cell regulation resulting in the hyperproduction of natural autoantibodies.

Age Factors↗
PubMed1990

Natural thymocytotoxic autoantibodies in non-obese diabetic (NOD) mice: characterization and fine specificity.

The NOD mouse is a model of human juvenile type I diabetes mellitus. As in humans and in the BB rat model, the development of diabetes in NOD mice is accompanied by evident manifestations of cell-mediated and humoral autoimmunity. Beside autoantibodies directed at putative islet cell antigens, NOD sera contain antibodies with specificity for lymphocyte cell-surface determinants. Here we demonstrate that these anti-lymphocyte antibodies have the same characteristics of target cell specificity, of isotype, and of temperature reactivity, as do natural thymocytotoxic autoantibodies (NTA) from lupic NZB mice, or from mice undergoing polyclonal B cell activation. We also demonstrate that the thymocytotoxic activity of NOD sera is not due to cross-reactive anti-insulin antibodies. Biochemical characterization of the determinants recognized by these anti-lymphocyte antibodies reveals two membrane-associated proteins of 28 and 33 kD, partially similar to the two peptides recognized by NTA from NZB mice (30 and 33 kD). Altogether, these results suggest that NOD mice develop manifestations of polyclonal B cell activation similar to those observed in lupus-prone mice. The relationship of these anomalies with the organ-specific pancreatic disease remains to be properly evaluated.

Animals↗