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D R Wegmann

Publications and source records attributed to D R Wegmann.

16 recordsLinked to original sources
PubMed2001

T-cell epitope analysis on the autoantigen phogrin (IA-2beta) in the nonobese diabetic mouse.

The protein tyrosine phosphatases (PTPs) IA-2 and phogrin (IA-2beta) are major autoantigens in type 1 diabetes that possess common serological epitopes in their COOH termini. The epitopes recognized by the T-cells that cause the disease, however, remain to be defined. Eight phogrin-specific T-cell clones were generated from NOD mice, and their epitopes were mapped. The mapping was performed initially with recombinant gluthathione S-transferase-phogrin COOH deletion constructs and ultimately with overlapping synthetic peptides. Two dominant epitopes were identified: one (aa 629-649) immediately adjacent to the transmembrane domain (aa 604-628) and the second (aa 755-777) lying in the NH(2)-terminal region of the conserved PTP domain. T-cells that are specific to either of these peptides and that could destroy islet tissue in vivo though spontaneous T-cell proliferative responses were observed in prediabetic female NOD splenocytes only to the aa 755-777 epitope. In NOD female mice immunized with the epitope peptide, intramolecular determinant spreading occurred from the aa 629-649 epitope to the aa 755-777 epitope but not in the opposite direction. We concluded that the initial T-cell response to phogrin is restricted to a small number of dominant peptides and that it subsequently spreads to other regions of the molecule, including those containing the major humoral epitopes that are highly conserved between IA-2 and phogrin.

Amino Acid Sequence↗
PubMed2000

It's insulin.

Explore the source record for details and available documents.

Animals↗
PubMed1999

Heterophile anti-mouse immunoglobulin antibodies may interfere with cytokine measurements in patients with HLA alleles protective for type 1A diabetes.

Wilson and coworkers (Wilson SB, Kent SC, Patton KT, Orban T, Jackson RA, Exley M, Porcelli S, Schatz DA, Atkinson MA, Balk SP, Strominger JL, Hafler DA: Extreme Th1 bias of invariant V alpha24J alpha Q T-cells in type 1 diabetes. Nature 391:177-181, 1998) have recently reported raised serum levels of interleukin-4 (IL-4) in anti-islet autoantibody-positive first-degree relatives of patients with type 1A diabetes who did not progress to diabetes. Protection from diabetes has been noted for several human lymphocyte antigen (HLA) alleles, such as HLA DR2-DQA1*0102-DQB1*0602. We, therefore, wanted to determine whether this cytokine phenotype was associated with HLA genes protective for type 1A diabetes. We used a two-site fluoroimmunoassay with the same monoclonal antibodies as those reported by Wilson et al. Using this assay, we have found evidence for human heterophile antibodies mimicking serum IL-4: all serum IL-4 reactivity was lost if mouse serum or mouse immunoglobulin were added to the assay; serum IL-4 activity was bound and then eluted by protein A/G chromatography; and levels of anti-mouse antibodies correlated with apparent serum IL-4. This pseudo-IL-4 activity was found in a subset of control subjects, patients with type 1A diabetes, and their relatives and was primarily associated with specific HLA alleles protective for type 1A diabetes (e.g., DQB1*0602). After adjustment for HLA, positive levels of heterophile antibodies were not associated with protection from diabetes. The confounding effect of protective HLA alleles associated with heterophile antibodies could explain the previously reported association between raised serum IL-4 and protection from type 1A diabetes. The mechanism by which specific DQ alleles protect from diabetes and are associated with increased heterophile antibodies is currently unknown.

Alleles↗
PubMed1999

Immunologic "vaccination" for the prevention of autoimmune diabetes (type 1A).

Diabetes type 1A is an autoimmune condition characterized by lymphocytic infiltration of islets and selective destruction of insulin-secreting beta-cells. Numerous investigators have prevented diabetes in animal models with a variety of antigens and routes of administration. It is also now possible to identify high-risk individuals even before the appearance of autoantibodies. These advances have created the opportunity to design and begin human prevention trials. This review focuses on a variety of immunomodulatory approaches (including administration of adjuvants, autoantigens, T-cells, T-cell receptors, and DNA) that we have collectively termed immunologic "vaccination." In addition, we discuss the potential benefits and dangers of these approaches and issues relating to the design of human trials.

Adjuvants, Immunologic↗
PubMed1997

T cell receptor gene polymorphisms associated with anti-insulin, autoimmune T cells in diabetes-prone NOD mice.

The great majority of insulin-specific T cell clones isolated from islets of NOD mice react with insulin peptide B-(9-23) (amino acids 9-23 of the insulin B chain). The T cell receptors of these clones contain diverse beta-chains but restricted alpha-chains. The dominant alpha-chain motif is a V alpha 13 segment (10 out of 13) combined to either a J alpha 45 or a J alpha 34 segment (eight out of 13). Furthermore, nine out of 10 of these V alpha 13 segments are a product of a novel NOD TCR V alpha gene which we have termed V alpha 13.3. Analysis of V alpha 13 transcripts from splenic cDNA libraries from the NOD, BALB/c and C57BL/6 mice revealed significant differences between strains. The NOD sequences contained both V alpha 13.1 and the novel V alpha 13.3. The BALB/c contained the previously reported V alpha 13.1 and V alpha 13.2, but not the V alpha 13.3 sequence identified in the NOD anti-insulin T cell clones. The C57BL/6 had V alpha 13.1 and V alpha 13.3 plus two additional novel sequences which we have termed V alpha 13.4 and V alpha 13.5. These V alpha 13 subfamily members differed by two to four amino acids in either the CDR1 region or adjoining the CDR2 region. The frequency of utilization of the different V alpha 13 subtypes varied dramatically between strains. In the NOD spleen, V alpha 13.3 was detected 79% of the time, compared to 21% for V alpha 13.1. In contrast, the C57BL/6 spleen contained only 7% of V alpha 13.3 sequences compared to the other subfamily members present (V alpha 13.1: 27%; V alpha 13.4: 56%; V alpha 13.5: 10%). MHC polymorphisms or other unknown selective pressures may contribute to these differences in V alpha 13 utilization. We hypothesize that the presence and frequent utilization of the V alpha 13.3 T cell receptor element is involved in targeting insulin B-(9-23) and may be related to diabetes susceptibility of NOD mice.

Animals↗
PubMed1997

T-cell reactivity to GAD65 peptide sequences shared with coxsackie virus protein in recent-onset IDDM, post-onset IDDM patients and control subjects.

GAD65 is one of the major autoantigens associated with insulin-dependent diabetes mellitus (IDDM). The two peptides p17 and p18 of GAD65 that share sequence similarity with coxsackie virus (amino acid sequence identity: PEVKEK) appeared to be the major determinants of GAD65 recognized preferably by T cells from new-onset IDDM patients and their first degree relatives. In contrast, in our study unrelated control subjects frequently recognized the two GAD peptides (55%, 16/29), similar to first degree relatives (41%, 12/29) and IDDM patients post-onset (68%, 15/22). However, recent-onset IDDM patients, responded less frequently (25%, 4/16) compared with IDDM patients post-onset (p < 0.03) or unrelated control subjects (borderline significant) confirming previous observations in humans and NOD mice that T-cell reactivity to GADp17/p18 at diabetes onset is decreased. Moreover, this study demonstrated a positive correlation of T-cell proliferation to GAD p17 (amino acid 247-266) and p18 (amino acid 260-279) with simultaneous responses to both peptides in 13% of all subjects tested (n = 97) (p < 0.001). T-cell proliferation to GAD p17 was higher than to p18 in recent-onset diabetic patients, first degree relatives and unrelated control subjects (p < 0.02, p < 0.004, p < 0.002, respectively). However, in post-onset IDDM patients, the two peptides were recognized equally well. Our results show that T-cell reactivity to GAD65, peptides homologous with coxsackie protein is very frequently observed, but not primarily associated with IDDM. The temporary decline of T-cell proliferation is not associated with the beta-cell destruction process, but with clinical manifestation. The positive correlation of reactivity to the two peptides in the viral motif implicates that PEVKEK is an immunogenic epitope.

Adolescent↗
PubMed1996

Protection of nonobese diabetic mice from diabetes by intranasal or subcutaneous administration of insulin peptide B-(9-23).

The observation that overt type I diabetes is often preceded by the appearance of insulin autoantibodies and the reports that prophylactic administration of insulin to biobreeding diabetes-prone (BB-DP) rats, nonobese diabetic (NOD) mice, and human subjects results in protection from diabetes suggest that an immune response to insulin is involved in the process of beta cell destruction. We have recently reported that islet-infiltrating cells isolated from NOD mice are enriched for insulin-specific T cells, that insulin-specific T cell clones are capable of adoptive transfer of diabetes, and that epitopes present on residues 9-23 of the B chain appear to be dominant in this spontaneous response. In the experiments described in this report, the epitope specificity of 312 independently isolated insulin-specific T cell clones was determined and B-(9-23) was found to be dominant, with 93% of the clones exhibiting specificity toward this peptide and the remainder to an epitope on residues 7-21 of the A chain. On the basis of these observations, the effect of either subcutaneous or intranasal administration of B-(9-23) on the incidence of diabetes in NOD mice was determined. The results presented here indicate that both subcutaneous and intranasal administration of B-(9-23) resulted in a marked delay in the onset and a decrease in the incidence of diabetes relative to mice given the control peptide, tetanus toxin-(830-843). This protective effect is associated with reduced T-cell proliferative response to B-(9-23) in B-(9-23)-treated mice.

Administration, Intranasal↗
PubMed1996

Peripheral T cell clones from NOD mice specific for GAD65 peptides: lack of islet responsiveness or diabetogenicity.

The non-obese diabetic (NOD) mouse develops diabetes as a result of spontaneous T cell mediated destruction of the insulin-producing beta-cells. Tolerization to glutamic acid decarboxylase (GAD65) has been reported to inhibit spontaneous T cell proliferative responses to GAD65 and GAD65 peptides and prevent insulitis and diabetes in NOD mice. To evaluate the role of T cells responsive to GAD65 in induction of diabetes in NOD mice we generated T cell clones from spleen cells of three prediabetic NOD mice using the reported immunodominant human GAD65 peptides nos. 17, 34 and 35, which are spontaneously recognized by NOD spleen cells. The ten T cell clones established from two female and one male NOD mice recognized either the GAD65 peptide no. 35 which has an identical amino acid sequence in mice and humans or recognized the human GAD65 peptide no. 17 which is different in two amino acids from murine GAD65 peptide no. 17. None of the clones exhibited responses to islet cells, and GAD65 peptide no. 17 responsive clones did not cross react with the murine GAD65 peptide no. 17. All clones were CD4 positive and expressed the alpha/beta T cell receptor, but differed in their V beta usage. Analysis of in vitro production of IFN gamma, IL-2 and IL-4 demonstrated a TH1 and TH0 like functional subset of the individual clones. In vivo, neither the autoreactive T cell clones specific for GAD65 peptide no. 35 nor the xenoreactive clones specific for GAD65 peptide no. 17 were able to accelerate diabetes in young NOD mice or transfer diabetes into NODscid mice.

Amino Acid Sequence↗
PubMed1996

The immune response to islets in experimental diabetes and insulin-dependent diabetes mellitus.

Over the past year, a number of important observations have been made in the nonobese diabetic mouse and in clinical insulin-dependent diabetes mellitus concerning the autoimmune response to islets. Assays have advanced to the point where individuals at risk for insulin-dependent diabetes mellitus can be readily identified prior to the onset of symptoms and a number of peptides of proteins expressed by the beta cell have been shown to protect nonobese diabetic mice from developing diabetes. The contributions of CD4+ and CD8+ T cells to beta cell destruction are beginning to be understood and this information will probably be of value in the design of intervention strategies for use in human subjects.

Animals↗
PubMed1994

Insulin-specific T cells are a predominant component of islet infiltrates in pre-diabetic NOD mice.

Numerous investigation have demonstrated that T cells are involved in destruction of beta cells in the NOD mouse, a widely studied model of type I diabetes. In this report we describe a series of islet-specific T cell lines established from islet-infiltrating lymphocytes obtained from individual pre-diabetic NOD mice as well as a large panel of clones derived from these lines. Proliferation assays indicated that these nominally islet-specific lines responded vigorously to porcine insulin. Furthermore, of 40 islet-specific clones derived from lines established from 12-week-old mice, 22 (55%) responded to insulin. A similar analysis of islet-specific clones established from 7-week-old mice indicated that 2 of 14 (14%) were insulin specific. These findings demonstrate that insulin-specific T cells can comprise a major portion of the spontaneously arising T cell response to islets in NOD mice.

Animals↗
PubMed1994

Analysis of the spontaneous T cell response to insulin in NOD mice.

Insulin-specific T cells have been found to be present in high frequency among nominally islet-cell-specific T cells in the islet infiltrates that accumulate in NOD mice. In a previous report in which clones obtained from 7- and 12-week-old mice were examined, we identified a 15-residue peptide of the B chain as the dominent epitope for this response. Despite the fact that the response to insulin appears to be directed toward this single peptide, diverse TCR V beta usage was observed. That insulin-specific T cells contribute to beta cell damage is suggested by the fact that all clones tested could mediate beta cell destruction upon adoptive transfer. In the present report we extend this examination of insulin-specific T cells to lines and clones established from mice ranging in age from 4-12 weeks. These clones were found to be very similar to those from 7- and 12-week-old mice. The response was directed to the same peptide and most were found to produce IFN gamma, but none produced IL-4.

Age Factors↗
PubMed1993

Establishment of islet-specific T-cell lines and clones from islet isografts placed in spontaneously diabetic NOD mice.

One impediment to detailed characterization of islet-specific T cells from the NOD mouse model of diabetes is the difficulty encountered in isolation of such cells. This report describes a method that allows routine isolation of relatively large numbers of T cells highly enriched for reactivity toward islet antigens. The method involves renal subcapsular transplantation of spontaneously diabetic NOD mice with NOD islets. These grafts are rapidly destroyed in a tissue-specific manner and this destruction is accompanied by lymphocytic infiltration. Here we demonstrate that the islet graft infiltrates are an excellent source of islet-specific T cells and that islet-specific T-cell lines and clones can be established from these cells. Islet-specific T-cell clones isolated from a T-cell line established from the islet graft infiltrates were capable of adoptive transfer of diabetes to NOD/LtSz-scid recipients.

Animals↗
PubMed1986

Interferon-gamma-induced IA expression in WEHI-3 cells is enhanced by the presence of 1,25-dihydroxyvitamin D3.

It has been suggested recently that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] is involved in the regulation of the immune functions of lymphocytes and in the differentiation of monocytic cells. This report examined the possibility that 1,25(OH)2D3 influences immune functions mediated by monocytic cells by studying its effect on the murine myelomonocytic line WEHI-3. We found that WEHI-3 cells possess 3.3S receptor proteins with high affinity (Kd = 3.3 X 10(-10) M) for 1,25(OH)2D3 that are capable of binding to DNA. Also we found that 1,25(OH)2D3 enhances the interferon-gamma (IFN-gamma)-induced expression of the class II major histocompatibility complex antigens (Ia molecules), and such enhancement leads to increased capacity of the WEHI-3 cells to stimulate antigen-specific Ia-restricted T cell activation. Finally, 1,25(OH)2D3 inhibits the proliferation of WEHI-3 cells, and this inhibition is enhanced in the presence of IFN-gamma. The 1,25(OH)2D3 modulation of IFN-gamma induction of Ia antigens suggests that the hormone might promote monocytes to function more efficiently as antigen-presenting cells.

Animals↗
PubMed1986

Recognition of exon-shuffled class II molecules by T helper cells.

Exon shuffled I-A beta genes transfected into the B lymphoma cell line A20-2J were used to localize the epitope recognized by the monoclonal antibody 10.2.16 to the carboxy terminal portion of the beta 1 domain. In addition, several T helper cell hybrids were tested against these novel I-A molecules and the following observations were made: the beta 1 domain of A beta plays a dominant role in the restricted recognition by T helper cells; there appear to be multiple restriction epitopes on the I-A molecule; these epitopes can consist of conformational epitopes created by specific alpha and beta chains or consist of the polymorphic determinants encoded on the beta chain alone, and these novel I-A molecules serve as restriction elements in the antigen-specific recognition by T cells and in one case stimulate an alloreaction in the absence of antigen.

Amino Acid Sequence↗
PubMed1986

Antigen presentation by a B-cell line transfected with cloned immunoglobulin heavy- and light-chain genes specific for a defined hapten.

The rearranged genes encoding immunoglobulin heavy (mu) and light (kappa) chains specific for the hapten 2,4,6-trinitrophenyl (Tnp) were introduced into a B-lymphoma line that bears surface IgG with an unknown specificity and expresses surface Ia molecules. A transformant expressing surface IgM specific for Tnp was obtained. The transformant was found to present Tnp-proteins to antigen (protein)-specific T cells far more efficiently than the parenteral B-lymphoma line. This artificial system, utilizing recombinant DNA technology and gene transfer, provides several approaches for the study of T-cell-B-cell interactions.

Animals↗