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D Wegmann

Publications and source records attributed to D Wegmann.

18 recordsLinked to original sources
PubMed2001

Report from the 1st International NOD Mouse T-Cell Workshop and the follow-up mini-workshop.

A workshop on autoreactive T-cell responses in NOD mice was held to optimize autoreactive T-cell detection methodologies. Using different proliferation assay protocols, 1 of the 11 participating laboratories detected spontaneous T-cell responses to GAD(524-543) and insulin(9-23) in their NOD mice. Two other laboratories were able to detect autoreactive responses when using enzyme-linked immunospot assay (ELISPOT) and enzyme-linked immunosorbent assay (ELISA) analysis of cytokines in culture supernatants, suggesting that these assays provided greater sensitivity. To address the divergent findings, a follow-up mini-workshop tested NOD mice from four different colonies side-by-side for T-cell proliferative responses to an expanded panel of autoantigens, using the protocol that had enabled detection of responses in the 1st International NOD Mouse T-Cell Workshop. Under these assay conditions, 16 of 16 NOD mice displayed proliferative responses to whole GAD65, 13 of 16 to GAD(524-543), 9 of 16 to GAD(217-236), 7 of 16 to insulin(9-23), and 5 of 16 to HSP277. Thus, spontaneous proliferative T-cell responses can be consistently detected to some beta-cell autoantigens and peptides thereof. Overall, the results suggest that more sensitive assays (e.g., ELISPOT, ELISA analysis of cytokines in supernatants, or tetramer staining) may be preferred for the detection of autoreactive T-cells.

Animals↗
PubMed2001

Peptide and major histocompatibility complex-specific breaking of humoral tolerance to native insulin with the B9-23 peptide in diabetes-prone and normal mice.

NOD mice spontaneously develop anti-insulin autoantibodies and diabetes. A dominant peptide recognized by T-cell clones from NOD mice is insulin B-chain peptide B9-23. When administered subcutaneously to NOD mice, this peptide decreases the development of diabetes. In this study, we evaluated the autoantibody response to native insulin after administration of the B9-23 peptide. In NOD mice, administration of the B9-23 peptide in incomplete Freund's adjuvant enhanced their insulin autoantibody response with a higher level and longer persistence. Induction of insulin autoantibodies with the B9-23 peptide was observed in non-diabetes-prone BALB/c mice and NOR mice within 2 weeks of administration, but this was not observed in C57BL/6 mice. A series of A-chain, other B-chain, and proinsulin peptides did not induce insulin autoantibodies. Induced anti-insulin autoantibodies could not be absorbed with the peptide alone but could be absorbed with native insulin. The B13-23 peptide (one of two identified epitopes within B9-23) when administered to BALB/c mice, induced autoantibodies, whereas peptide B9-16 did not. Induction of autoantibodies mapped to the major histocompatibility complex (MHC) rather than to the background genes. Both splenocytes with I-A(d)/I-E(d) or I-A(g7)/I-E(null) presented the B9-23 peptide to NOD islet-derived T-cell clones. Finally, administration of the B9-23 peptide to BALB/c mice, even without adjuvant, could induce insulin autoantibodies. Our results indicate that B-cell tolerance to intact insulin is readily broken with the presentation of the B9-23 insulin peptide, depending on the host's specific MHC.

Animals↗
PubMed2000

Dual overlapping peptides recognized by insulin peptide B:9-23 T cell receptor AV13S3 T cell clones of the NOD mouse.

T cells isolated from islets of non-obese diabetic (NOD) mice are enriched for insulin-reactive cells. The great majority of these T cells recognize insulin B chain peptide (B:9-23). B:9-23 reactive T cell clones are diabetogenic and show a dramatic TCR alpha -chain restriction (predominant AV13S3). We have studied the reactivity of five different B:9-23 reactive T cell clones to truncated peptides and alanine substituted analogues of B:9-23. Amongst these AV13S3 T cell clones, one reacted with peptide B:9-16 and four with B:13-23. The two peptides have in common only four amino acids (B:13-16; EALY). Having defined minimal peptide epitopes, we evaluated a mutant insulin sequence (B:13 glutamine) which retains metabolic activity. As predicted, this single amino acid change abrogated T cell reactivity. In addition, we have created a modified I-A(g7)gene with the B:9-23 peptide covalently linked to I-A(g7). Antigen presenting cells transfected with this construct were excellent presenting cells for all clones studied. The definition of dual peptide motifs and creation of bioactive covalent I-A(g7)-B:9-23 should facilitate studies of the pathogenic significance and antigen recognition by B:9-23 reactive diabetogenic T cells.

Alanine↗
PubMed1999

Cellular immune response to phogrin in the NOD mouse: cloned T-cells cause destruction of islet transplants.

The ability of nonobese diabetic (NOD) mice to mount a cellular immune response to the secretory granule protein tyrosine phosphatase (PTP), phogrin was evaluated by immunization of 8- to 12-week-old animals with recombinant phogrin in complete Freund's adjuvant. Draining lymph nodes displayed a robust proliferative response to the protein, as did derived T-cell lines and clones. Ten clones obtained by limiting dilution were all CD4+ and of a T-helper-1-like phenotype, but showed variation in their Vbeta usage. Of the 10 clones, 3 responded to endogenous antigens in rat islets. Two of these caused the destruction of rat islets that had been transplanted under the kidney capsule of streptozotocin-treated NOD scid mice without affecting adjacent thyroid implants. The results demonstrate the feasibility of generating antigen-specific diabetes-inducing CD4+ cells by direct immunization of NOD mice and their potential use for further studies of the antigenic epitopes in the PTP family members. The conclusion, based on serological studies, that PTP members do not play a role in the pathogenesis of type 1 diabetes in rodent models needs reevaluation in light of these findings.

Animals↗
PubMed1997

T cell receptor restriction of diabetogenic autoimmune NOD T cells.

Restricted use of T cell receptor (TCR) gene segments is characteristic of several induced autoimmune disease models. TCR sequences have previously been unavailable for pathogenic T cells which react with a defined autoantigen in a spontaneous autoimmune disease. The majority of T cell clones, derived from islets of NOD mice which spontaneously develop type I diabetes, react with insulin peptide B-(9-23). We have sequenced the alpha and beta chains of TCRs from these B-(9-23)-reactive T cell clones. No TCR beta chain restriction was found. In contrast, the clones (10 of 13) used V alpha13 coupled with one of two homologous J alpha segments (J alpha45 or J alpha34 in 8 of 13 clones). Furthermore, 9 of 10 of the V alpha13 segments are a novel NOD sequence that we have tentatively termed V alpha13.3. This dramatic alpha chain restriction, similar to the beta chain restriction of other autoimmune models, provides a target for diagnostics and immunomodulatory therapy.

Amino Acid Sequence↗
PubMed1997

Altered immune response to insulin in newly diagnosed compared to insulin-treated diabetic patients and healthy control subjects.

Insulin-dependent diabetes mellitus (IDDM) is the result of a T-cell mediated autoimmune beta-cell destruction, which is accompanied by autoantibodies. We analysed the cellular and humoral immune response to insulin and insulin peptides in patients with recent-onset IDDM, IDDM patients treated with insulin, non-diabetic first degree relatives and unrelated control subjects. There were no differences in T-cell reactivity to whole insulin or insulin peptides in general between age-matched groups of IDDM patients, relatives or healthy control subjects. In contrast to investigations in NOD mice, no immunodominant or disease-specific insulin peptide could be identified. Surprisingly, a positive correlation of T-cell responses to insulin with age was noticed (p < 0.005). This resulted in an inverse relation of insulin autoantibodies (IAA) and insulin reactive T-cells (p < 0.001) together with the well-described negative correlation of IAA with age. Interestingly, insulin-treated patients differed from age-matched recent-onset IDDM patients: first, simultaneous immune recognition of insulin with T-cells and IAA was only seen in patients treated for 6 months with insulin; second, insulin-treated patients rarely responded to whole insulin; third, they displayed less determinant spreading, and finally, recognition of multiple insulin peptides was not accompanied by crossreactivity to whole insulin. These distinct observations in insulin-treated IDDM patients, together with the inverse correlation between humoral and cellular responses to insulin, may result from activation or modulation of different T-cell subsets, and may be of relevance to insulin therapy trials, in which selective activation of non-destructive T-cell subsets may be a key to successful intervention.

Adolescent↗
PubMed1997

[Short evaluation of the QBC-Vet Autoread System].

The QBC-Vet Autoread-System (QBC = Quantitative Buffy Coat) is an advanced version of the OBC-Vet Haematology-System, to which an automatic reader and a printer have been added. In addition to the determination of haematocrit, haemoglobin, MCHC, white blood cell, granulocyte, lympho-/monocyte and platelet counts, measurement of eosinophils and neutrophils in dogs, and the estimation of reticulocytes and nucleated red blood cells in both dogs and cats are possible. The aim of this study was to evaluate the QBC-Vet Autoread-System with respect to its suitability in veterinary practice. Samples collected from 213 mostly ill animals were analysed and the results compared with conventionally measured values. The system was found to be easy both in handling and interpretation of results. Accuracy was found to be good for the majority of the parameters (correlation coefficients: haematocrit r > 0.96, WBC r > 0.89). The printed buffy coat profile was found to be very useful to verify accuracy of results immediately and to prevent misinterpretations. Although this is a preliminary study with a small number of samples, the QBC-Vet Autoread-System was found to be a true improvement over the older system and will be very useful in veterinary practices.

Animals↗
PubMed1996

Diabetogenic T-cell clones.

The role of T-cells in the pathogenesis of IDDM has been an area of much interest, and investigators have recently acquired new tools for studies on T-cells with the advent of T-cell clones that are reactive with islet antigens. Derived from NOD mice, diabetogenic T-cell lines and clones have for the most part been CD4+ and T-helper 1 (Th1)-like in their cytokine production. Some CD8+ cytotoxic clones have also been reported, although these have generally not transferred diabetes in the absence of CD4+ T-cells. The T-cell clones that have been described can also be separated on the basis of their antigen reactivity. While many of the T-cell lines and clones described react with islets, isolated islet cells, or islet membrane preparations, others have known antigen specificities, reacting with defined islet cell proteins such as insulin, GAD, and heat shock proteins. Particularly in the case of insulin-reactive clones, diabetogenicity has also been demonstrated. In light of the many possible T-cell reactivities that may arise from the islet lesion, the question of whether there is a dominant initiating antigen is a particularly intriguing one.

Animals↗
PubMed1995

Epitope specificity, cytokine production profile and diabetogenic activity of insulin-specific T cell clones isolated from NOD mice.

T cells are known to play an important role in beta cell destruction in the nonobese diabetic (NOD) mouse model of Type I diabetes and islet-specific T cell clones have been demonstrated to be capable of adoptive transfer of diabetes. One important issue involves the identity of beta cell antigens that are recognized by nominally islet cell-specific T cell clones. We have previously reported that insulin-specific T cells are a predominant component of islet-specific T cells isolated from islet infiltrates of pre-diabetic NOD mice. In this report we examine six independently derived insulin-specific T cell clones established from islet infiltrates of pre-diabetic NOD mice in detail. All six clones were found to be specific to a region of the insulin molecule defined by a synthetic peptide encompassing residues 9-23 of the B chain. Despite this restricted specificity, each member of this panel exhibited a distinct receptor specificity defined either by V beta usage or antigen fine specificity. Five clones produced interferon (IFN)-gamma but not interleukin (IL)-4, placing them in the T helper type 1 (TH1)-like category whereas one clone produced both IL-4 and IFN-gamma, a characteristic of TH0 cells. All six clones were capable of either acceleration of diabetes in young NOD mice or adoptive transfer to NODscid mice. Taken together, these results suggest that spontaneously arising insulin-specific T cells participate in beta cell destruction during development of diabetes in NOD mice.

Amino Acid Sequence↗
PubMed1993

[Periodic hypokalemic paralysis in thyrotoxicosis].

The case is reported of a 26-year-old Chinese cook hospitalized for hypokalemic paralysis, the cause of which was found to be thyrotoxicosis. In Asian males hypokalemic periodic paralysis occurs in 2% to 10% of thyrotoxic patients with a male:female ratio of close to 70:1. In the white population the frequency is smaller by a factor of 10. This association is however considered important, since the clinical symptoms of thyrotoxicosis may be scanty. By successful treatment of thyrotoxicosis hypokalemic paralysis disappears, but may return after cessation of treatment. Pathogenetically, hyperreactivity of the sodium/potassium pump of the cell membrane seems to play an important role.

Adult↗
PubMed1992

[Eosinophilic colitis--an unusual cause of acute abdomen. Case report and literature review].

Eosinophilic gastroenteritis (EGE) is an etiologically obscure and rare inflammation which can affect all sections of the gastrointestinal tract from esophagus to rectum in a diffuse or segmentary manner. An infiltrate of eosinophilic granulocytes is found to varying degrees in all wall layers. The clinical symptoms depend on the site and extent of organ involvement. Diagnosis can only be established histologically. Peripheral eosinophilia is inconsistent and not diagnostic. ESR, leukocyte count, serum IgE, and RAST tests in foodstuffs may be normal or elevated. Two women patients are described with tumorous eosinophilic colitis of the cecum and colon ascendens, who underwent surgery for clinical acute abdomen. A further woman patient was hospitalized with bloody diarrhea and marked eosinophilia in the blood findings. Eosinophilic colitis was likewise found histologically in the mucosa which appeared with reddened patches in sigmoidoscopy. Eosinophilic colitis associated with eosinophilic gastroenteritis is rather rare and may therefore be overlooked. Our literature review contains only 64 such cases, in only 6 of which was the tumorous form found. Counting our own patients as well, eosinophilic colitis occurs somewhat more frequently in women (27 = 56%) than in men (21 = 44%). The clinical symptoms, possible causes and therapeutic approaches are discussed in the light of the literature.

Abdomen, Acute↗
PubMed1992

High efficiency presentation of TNP-conjugated islet antigen to islet-specific T cells by a hybrid B cell line expressing TNP-specific surface Ig.

There is compelling evidence from animal models that type I diabetes is a consequence of T cell-mediated destruction of islet beta-cells. The recent isolation of islet-specific T cell clones from nonobese diabetic mice provides a means of identification of the Ag on islet cells that are responsible for stimulation of autoreactive T cells. We describe an APC line constructed by fusion of spleen B cells obtained from nonobese diabetic mice to a B lymphoma that was transfected with the H and L chains of an IgM specific to the hapten TNP. Using this hybrid APC we have observed a dramatic increase in the efficiency of presentation of TNP-conjugated islet cell protein preparations compared to that seen with conventional APC. Our results illustrate the potential use of this APC line for isolation and characterization of islet Ag relevant to the T cell response.

Adenoma, Islet Cell↗
PubMed1988

T-lymphocyte clone specific for pancreatic islet antigen.

A cloned T-lymphocyte line, BDC-2.5, was derived from a nonobese diabetic (NOD) mouse and has been found to exhibit specificity for islet cell antigen in vitro and in vivo. This clone is a CD4+ T-lymphocyte that proliferates and makes lymphokine in response to islet cell antigen- and NOD antigen-presenting cells. In an in vivo transplantation system in which islet grafts were made in the presence or absence of the BDC-2.5 T-lymphocytes, it was found that incorporation of the islet-specific T-lymphocytes into the graft site resulted in complete destruction of the transplanted tissue. Similar grafts made with pituitary tissue were not affected by the T-lymphocyte clone. These results suggest that the islet-specific T-lymphocytes mediate islet destruction in a tissue-specific manner.

Animals↗
PubMed1987

Relationship of B cell Fc receptors to T cell recognition of Mls antigen.

The Mls locus on chromosome 1 controls the expression of cellular determinants that are responsible for stimulating mixed lymphocyte reactions between H-2-identical strains. However, the biochemical nature of Mls antigenic determinants remains undefined. It has been proposed that Ly-17 lymphoid cell surface antigens (also known as Ly.m.20.2 and LyM-1) and Mls antigens could be identical because they are both encoded by loci on chromosome 1 and display similar tissue distribution. The Ly-17 locus encodes polymorphic alleles of the IgG Fc receptor (Fc gamma R). In the present study, two approaches were used to address the question of whether Fc gamma R are involved in T cell recognition of Mls antigen. In the first approach we tested the effect of Fc gamma R blockade by heat-aggregated mouse IgG or anti-Fc gamma R monoclonal antibodies (2.4.G2) on the ability of an Ia+, Fc gamma R+ Mlsa-expressing B cell hybrid (LBB.3.4.16) to stimulate interleukin 2 secretion by an anti-Mlsa-specific T cell hybrid. We show that blockade of Fc gamma R does not inhibit the Mlsa-specific stimulation of T cells during a 24-h culture period in which Fc gamma R remain blocked. In the second approach, we derived irradiation-induced variants of LBB.3.4.16 to dissociate Fc gamma R expression and Mls antigen expression. We describe 2 LBB variants which no longer stimulate Mlsa-reactive T cells but do express Fc gamma R. Compared to parental LBB cells, the capacity of variant LBB cells to present soluble antigen to Ia-restricted T cells is unaffected. Collectively, these results indicate that Fc gamma R expression and Mlsa antigen stimulation can be dissociated. We conclude that Fc gamma R expression may be necessary, but not sufficient for T cell recognition of Mls antigen.

Animals↗
PubMed1982

Antigen presentation by Ia+ B cell hybridomas to H-2-restricted T cell hybridomas.

The Ia+, H-2d BALB/c lymphoma cell line L10.A 2J was fused to T cell-depleted spleen cells from mouse strains bearing other H-2 haplotypes. A portion of the selected hybrids expressed Ia antigens of the normal spleen cell partner in the fusion as evidenced by their presentation of various antigens to a set of antigen-specific I-region-restricted T cell hybridomas. Three cloned hybrids were studied in detail. Antigen presentation was shown to be inhibited specifically by monoclonal anti-Ia antibodies. Both I-A and I-E molecules were expressed, including in the one case examined hybrid I-A and I-E molecules between the H-2d and H-2b haplotypes. These Ia+ B cell hybridomas provide a useful set of tools for studying the role of I-region-encoded molecules in antigen presentation to T cells.

Antibody Formation↗