Evidence for two discontinuous regions on the thyrotropin receptor involved in the binding of the monoclonal antibody 34A.

The human thyrotropin receptor (hTSHR) is a major autoantigen in thyroid autoimmunity. The aim of this study was to localize the discontinuous epitope recognized by the anti-hTSHR monoclonal antibody (mAb) 34A. We used the phage-displayed peptide technology and selected thirteen 34A-specific mimotopes which could be grouped into four families according to their sequence homologies.

Role of IL-10 in the distribution of B cell subsets in the mouse B-1 cell population.

The B lymphocyte compartment is comprised of B-1 and B-2 cells. The former is divided into B-1a, which express CD5, and B-1b cells which do not: both are self-renewing, although the mechanisms are yet to be identified. IL-10-/- mice were used to delineate the role of the B cell activator IL-10 in this process.

LPS and Freund's adjuvant initiate different inflammatory circuits in experimental autoimmune thyroiditis.

Although adjuvants are essential for the initiation of experimental autoimmune diseases, their precise contribution to the pathological manifestations is still poorly understood. Experimental autoimmune thyroiditis (EAT) is interesting in that respect because it can be initiated with the help of two different adjuvants Freund's complete or LPS which may initiate independent pathogenic pathways. In the present study, we have compared Freund's-induced versus LPS-induced EAT with respect to their dependence upon CD8+ T cells, which are considered as major actors in the pathogenesis of thyroiditis.

Chemokines modulate experimental autoimmune thyroiditis through attraction of autoreactive or regulatory T cells.

A critical event in the pathogenesis of experimental autoimmune thyroiditis (EAT) is the entry of thyroid-specific T lymphocytes into the thyroid gland. To investigate the role of soluble mediators in that infiltration, we have assayed the expression of various chemokines in diseased thyroid glands and in cytokine-treated cultures of normal thyroid epithelial cells. MCP-1 (monocyte chemotactic protein-1) and RANTES are produced during EAT and induced in vitro by IFN-gamma, IL-10, TNF-alpha, and IL-1beta.

The H2 haplotype regulates the distribution of B cells into B-1a, B-1b and B-2 subsets.

The size of B-cell subsets appears to be under genetic control, but the mechanism of this regulation is unknown. By analyzing five congenic strains of mice that differ only in their H2 haplotype, we addressed the issue of whether the MHC genes are involved in the relative proportions of B-1a, B-1b and B-2 cells. Not only were there considerable differences in the percentages of B-1 in B cells between H2s mice which were the highest [78.

Induction of experimental autoimmune thyroiditis by heat-denatured porcine thyroglobulin: a Tc1-mediated disease.

Recent studies have shown that denatured exogenous antigens can prime cytotoxic T lymphocytes (CTL). To assess the contribution of CTL to experimental autoimmune thyroiditis (EAT), porcine thyroglobulin (pTg) was heat-denatured (hdpTg) and injected i.v.

Curative treatment of experimental autoimmune thyroiditis by in vivo administration of plasmid DNA coding for interleukin-10.

The autoimmune response in experimental autoimmune thyroiditis (EAT) is characterized by a lymphocyte infiltration of the thyroid gland and by the appearance of circulating autoantibodies to thyroglobulin (Tg). Cytokines play a crucial role in the immunoregulation and pathology of EAT. Systemic administration of IL-10 has curative effects on EAT, but requires high doses and iterative injections due to the rapid turnover of this molecule.

Gene therapy of experimental autoimmune thyroiditis by in vivo administration of plasmid DNA coding for Fas ligand.

Fas-Fas ligand (FasL) interaction is required for the maintenance of immune homeostasis and seems to be responsible for the privileged immune status of some tissues. Experimental autoimmune thyroiditis (EAT), which is characterized by autoreactive T and B cell responses and a marked lymphocytic infiltration of the thyroid, is a model of choice to study the therapeutic effects of FasL. Here, we provide evidence that direct injection of DNA expression vectors encoding FasL into the inflamed thyroid inhibited development of lymphocytic infiltration of the thyroid and induced death of infiltrating T cells.

Effects of murine recombinant interleukin-10 on the inflammatory disease of rats transgenic for HLA-B27 and human beta 2-microglobulin.

Rats transgenic for HLA-B27 and human beta 2-microglobulin develop a spontaneous, multisystem, inflammatory disease that resembles human B27-associated disease and that involves the gut mucosa. This model predominantly affects the colon and is characterized by an extensive infiltration of the mucosa by inflammatory cells, largely composed of mononuclear cells. In addition, an increased plasma level of nitric oxide (NO)-derived metabolites was described in this model.

Phenothiazine-induced increase in thyroid autoantigens and costimulatory molecules on thyroid cells: a pathophysiological mechanism for drug-induced autoimmunity?

We have previously demonstrated (J Immunol 1995; 154:3593) that MHC class II antigens can be induced on thyroid epithelial cells (TEC) by alimemazine, a member of the phenothiazine group. Although this expression of MHC class II antigens on TEC confers the theoretical ability to behave as antigen-presenting cells (APC), the simultaneous expression of self antigens and co-receptor(s) must also occur for efficient presentation of self antigens. Therefore, we investigated whether alimemazine applied at pharmacologic doses would modify the expression of thyroid antigens, and simultaneously, the expression of intercellular adhesion molecule-1 (ICAM-1), B7, and LFA-1 co-receptors in human TEC in culture.

Experimental autoimmune thyroiditis (EAT) in mice lacking the IFN-gamma receptor gene.

To investigate the role of interferon-gamma (IFN-gamma) in experimental autoimmune thyroidits (EAT), H-2k mice with a disrupted IFN-gamma receptor (IFN-gamma R) gene were immunized with porcine thyroglobulin (pTg). We observed that EAT occurred on day 19 and remitted on day 35 in IFN-gamma R-deficient (IFN-gamma R(0/0)) mice, whereas in wild-type mice, EAT occurred on day 21 and remitted on day 42-49. Moreover, EAT in the mutant mice was attenuated and accompanied by diminished Tg-specific cytotoxic and proliferative responses and decreased titers of anti-Tg antibodies, notably of the IgG2a and IgG2b isotypes.

Analysis of susceptibility of NOD mice to spontaneous and experimentally induced thyroiditis.

Beside diabetes, non-obese diabetic (NOD) mice develop sporadic lymphoid infiltration of the thyroid gland, mimicking Hashimoto's thyroiditis. We have examined the prevalence of those manifestations in NOD mice, the influence of the major histocompatibility complex (MHC) and the association with autoantibodies. The incidence at 1 year is of 14.

[Predisposition to thyroid autoimmune diseases].

Objectives: Genetic predisposition is required for the expression of thyroid autoimmune disorder addition to the immune dysfunction and the environmental factors.

Methods: In order to evaluate the role of this genetic factor, we reported the results of immunological and hormonal investigations of 62 members (TD), belonging to a large Akr family, who are related to 40 patients with Graves' disease or Hashimoto's thyroiditis.

Results: The hormonal analyses showed that 19 subjects exhibited an infraclinical hypothyroidism, subdivided into 7 members with pathological rates of TSH evocative of thyroid insufficiency and 12 others with compensative thyroid insufficiency.

Influenza A virus hemagglutinin is a B cell-superstimulatory lectin.

Influenza A viruses display T cell-independent polyclonal B cell-activating properties which are mediated by the B cell-superstimulatory envelope glycoprotein hemagglutinin (HA). In this report, the receptor-binding requirements for B cell activation by influenza viruses were expected. Neuraminidase treatment of resting mature B cells from BALB/c mice abrogated late (proliferation/immunoglobulin synthesis), early (up-regulation of cell surface markers, including CD25, B220, and B7-1) and very-early events (homotypic adhesion) in virus-responding B lymphocytes.

Induction of experimental autoimmune thyroiditis (EAT) by heat-denaturated thyroglobulin (Tg).

Experimental Autoimmune Thyroiditis (EAT) is characterized by autoreactive T and B cell responses, assessed by a marked lymphocytic infiltration of the thyroid gland by T cells and the occurrence of circulating autoantibodies (AAb) to thyroglobulin (Tg). It was recently reported that administration of denaturated exogenous antigens primes class I-restricted cytotoxic T cells in vivo. Since cytotoxic T cells are involved in EAT development, porcine Tg (pTg) was heat-denaturated, i.

B cell superstimulatory influenza virus activates peritoneal B cells.

We evaluated the potential of B cell "superstimulatory" influenza viruses to activate peritoneal B cells (PBC) from BALB/c mice containing both CD5+ and CD5- "sister" cells. Like conventional B cells, PBCs responded to influenza viruses in a hemagglutinin glycoprotein (HA) subtype-specific manner with proliferation and vigorous Ig synthesis. However, a number of HA subtypes that are highly stimulatory for conventional B cells failed to induce significant responses of PBC.

Curative and protective effects of IL-10 in experimental autoimmune thyroiditis (EAT). Evidence for IL-10-enhanced cell death in EAT.

We studied the effects of in vivo administration of rhIL-10 in two models of experimental autoimmune thyroiditis (EAT): 1)-in EAT induced by injection of mTg emulsified in adjuvant, and 2) in EAT induced by adoptive transfer of mTg-specific T lymphocytes. Furthermore, we tried to assess both the protective and curative potential of IL-10 in EAT, by administering rhIL-10 either at the time of priming and challenge with mTg, or only at the time of challenge. We demonstrated that proliferative and cytotoxic responses of splenic cells to mTg were markedly reduced by in vivo rhIL-10 treatment.

Molecular heterogeneity of antigen- or idiotype-induced anti-thyroglobulin monoclonal autoantibodies.

To define the molecular basis of the cognitive interaction in experimental autoimmune thyroiditis (EAT), we sequenced the variable regions of monoclonal autoantibodies to thyroglobulin (Tg), specific or not for the F40D peptide, a Tg peptide capable of inducing EAT in CBA/J mice. Three MoAbs were obtained by immunization with syngeneic Tg of CBA/J (3B8G9, 2F6F2) or C57Bl/6 (4D11F4) mice. 3B8G9 was specific for F40D peptide, whereas 2F6F2 and 4D11F4 were not.

Distinctive modulation by IL-4 and IL-10 of the effector function of murine thyroglobulin-primed cells in "transfer-experimental autoimmune thyroiditis".

Experimental autoimmune thyroiditis (EAT) is characterized by autoreactive T and B cell responses, a marked lymphocytic infiltration of the thyroid gland, and the occurrence of circulating autoantibodies to thyroglobulin. Direct evidence for the involvement of lymphocytes stems from the observation that EAT can be induced in naive, irradiated CBA/J mice by transfer of in vitro restimulated effector spleen cells obtained from murine thyroglobulin (mTg)-immunized donors. Using this transfer-EAT (tEAT) model, we have investigated whether addition of recombinant murine IL-4 (rIL-4) or human IL-10 (rIL-10) during the in vitro restimulation by mTg would affect the subsequent induction of the disease.

Phenothiazine induces de novo MHC class II antigen expression on thyroid epithelial cells. A new mechanism for drug-induced autoimmunity.

Autoimmune responses are initiated by MHC class II-restricted T cell responses directed against tissue-specific autoantigens. Furthermore, HLA-DR expression in thyroid epithelial cells is a prominent feature of autoimmune thyroid disease. In the present work, we were particularly interested in a phenothiazine, a neuroleptic and anti-depressant drug of pharmacologic importance named alimemazine.

One monoclonal antibody to human thyrotropin (TSH) receptor agonist of TSH hormone stimulates the proliferation of human thyroid cells.

The question of thyroid cell growth induction by monoclonal antibodies (mAbs) to human thyrotropin receptor (hTSH-R), which stimulate increases in cAMP thyroid cells, is under debate and their implication in Graves' disease (GD) is controversial. In order to address this issue, we used characterized reagents, i.e.

Superantigens induce primary T cell responses to soluble autoantigens by a non-V beta-specific mechanism of bystander activation.

Superantigens have been suggested to act as powerful TCR V beta-specific inducers of T cell reactivity in autoimmune diseases. We have investigated the capacity of staphylococcal enterotoxins (SE) to prime autoreactive T cell responses in naive animals in the Lewis rat model of experimental autoimmune encephalomyelitis (EAE), where myelin basic protein (MBP)-specific CD4+ effector T cells express almost exclusively V beta 8.2 TCR elements.

B cell superstimulatory influenza virus (H2-subtype) induces B cell proliferation by a PKC-activating, Ca(2+)-independent mechanism.

The influenza virus hemagglutinin glycoprotein (HA) induces a vigorous B cell proliferation and Ig-synthesis by an unknown activation mechanism, which is susceptible to the inhibitory effects of anti-Ig and anti-class II mAbs. To gain further insight into the activation mode of this T cell-independent, B cell "superstimulatory" virus, we analyzed the sensitivity of H2-subtype virus-mediated B cell activation to the inhibitory effects of various signal transduction-blocking agents and compared it to the well characterized anti-mu-mediated and the LPS-employed pathway. Cyclic-AMP agonists (cAMP-analogues, pentoxifylline, cholera toxin, and forskolin) blocked HA-mediated activation of B cells only at concentrations at least 50-fold higher than required for blocking of anti-mu-induced activation.

Desensitization of the antigen receptor primes B cells for activation by superstimulatory influenza virus.

Interaction of the B cell receptor (BCR) with non-immunogenic receptor ligands can induce a specific state of B cell unresponsiveness as a result of receptor desensitization. Provided it is maintained over time, BCR desensitization may provide the molecular basis for clonal anergy. Using an in vitro model of anti-Ig-mediated BCR desensitization, we assessed the susceptibility of desensitized "anergic" B lymphocytes to activation by B cell superstimulatory influenza virus hemagglutinin (HA).