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C G Fathman

Publications and source records attributed to C G Fathman.

At least 73 records · Page 4Linked to original sources
PubMed1995

Islet-infiltrating lymphocytes from prediabetic NOD mice rapidly transfer diabetes to NOD-scid/scid mice.

In an effort to study the development of diabetes in NOD mice, our laboratory developed a novel adoptive transfer model using NOD-scid/scid (NOD-scid) mice as recipients of islet-infiltrating lymphocytes from donor prediabetic female NOD mice. We first confirmed previous results that demonstrated that splenocytes of diabetic and prediabetic female NOD mice could transfer diabetes to NOD-scid mice. We demonstrated that the kinetics of disease transfer were dependent on the age of transferred lymphocytes and reiterated the kinetics of diabetes in conventional female NOD mice. We then demonstrated that islet-infiltrating lymphocytes from prediabetic female NOD mice could transfer diabetes. In contrast with the age-dependent transfer of diabetes seen using splenocytes, islet-infiltrating lymphocytes obtained from prediabetic female NOD mice aged > or = 40 days rapidly transferred diabetes to NOD-scid recipients. The time required to transfer insulin-dependent diabetes mellitus (IDDM) using islet-infiltrating lymphocytes from young prediabetic mice (25 +/- 9 days) was not statistically different from the time required to transfer IDDM using splenocytes from overtly diabetic mice (32 +/- 5 days). Cotransfer of splenocyte cells or CD4+, but not CD8+ spleen cells, from 60- to 80-day-old prediabetic female NOD mice together with either splenocytes from diabetic mice or islet-infiltrating lymphocytes from prediabetic NOD mice delayed the rapid transfer of IDDM, suggesting that CD4+ cells mediated immunoregulation. Use of the NOD-scid islet-infiltrating lymphocyte-adoptive transfer model should help elucidate the pathophysiology of the early inflammatory events leading to insulitis and subsequent beta-cell destruction.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1994

CD4-positive/heat-stable antigen-positive thymocytes cause graft-versus-host disease across non-major histocompatibility complex incompatibilities.

Single-positive thymocytes are the immediate precursors of peripheral recent thymic emigrants (RTE) which develop into mature peripheral T cells. The functional ability of RTE is unclear but their state of differentiation may be relevant to the development of tolerance to peripheral "self" antigens. Since RTE are difficult to analyze, precursor CD4+/8- thymocytes were assessed in a model in vivo to determine their functional capability and their susceptibility to tolerance induction. The ability of both heat-stable antigen-positive (HSA+) (immature) and HSA- (mature) single-positive thymocytes to cause graft-versus-host disease (GVHD) across non-major histocompatibility complex differences were examined. Both HSA- and HSA+ CD4+/8- thymocytes from C3H mice caused lethal GVHD in AKR recipients as did CD4+ peripheral T cells in controls. Further, neonatal C3H thymocytes also caused lethal GVHD in AKR recipients. Since CD4+/8- thymocytes are the precursors of RTE, these results suggest that RTE are not susceptible to tolerance induced to "minor" antigens and may have a normal immune function in vivo. This would suggest that peripheral tolerance may be dependent upon the manner of antigen presentation rather than T cell maturity.

Animals↗
PubMed1994

Prevention of diabetes and insulitis by neonatal intrathymic islet administration in NOD mice.

The murine model of human insulin dependent diabetes mellitus (IDDM), the non-obese diabetic (NOD) mouse, develops a T cell-dependent destruction of pancreatic islets. While the target antigens are unknown, there is clearly a lack of tolerance to them. Neonatal intrathymic (i.t.) antigen injection has been successfully employed to prevent insulitis in BB rats but previous i.t. islet antigen studies in NOD mice were done on older mice. We have injected syngeneic islets into the thymus of NOD mice at birth and found that diabetes and insulitis can be completely prevented by this procedure. The effect is islet antigen-specific since other T cell responses, including autoimmune salivary infiltration, ard unaffected. Furthermore, contrary to previous studies, cyclophosphamide administration was unable to induce diabetes in treated mice which suggests that deletion or anergy might be the mechanism by which neonatal intrathymic islet injection protects from disease. However, anti-islet antigen antibodies were still present in these mice which suggests that the mechanism of disease protection may be more complex.

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PubMed1994

Regulation of autoimmune response.

Recent work on such apparently disparate fields as T-cell receptor peptide-induced regulation, superantigens, antigen-induced tolerance, models of peripheral tolerance, apoptosis, and T-cell receptor antagonists demonstrates a similarity in immune response from a regulatory perspective. In many systems, a 'tolerance' pathway is observed, characterized broadly as an initial disturbance in the immune system, with a resulting predominance of effector cells, followed by a homeostatic response (often requiring CD8+ cells) which leads the effector population into T-cell receptor downregulation, T-cell inactivation, anergy and, often, eventual apoptotic death. In the regulated immune response, mixed populations of anergized and apoptosing T cells can be found. In some cases, anergy appears to lead to death while, in other instances, cells revert to a functional state. This review focuses on recent papers examining each of these topics in an attempt to obtain a preliminary integrated picture of immune regulation in autoimmune diseases.

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PubMed1994

Mechanisms of transplantation tolerance.

Transplantation tolerance, the long-term acceptance of grafted tissue in the absence of continuous immunosuppression, remains an elusive goal in humans, but it has been achieved in animal models using numerous approaches. The mechanisms behind graft acceptance vary according to the means used to create the state of acceptance. Several major mechanisms can now be recognized. While thymic deletion of T cells appears to be a mainstay of self-tolerance, its role in transplantation tolerance now seems to be less significant. In contrast, extrathymic mechanisms of transplantation tolerance seem to be major factors in long-term graft acceptance. If donor antigens are presented in a nonimmunogenic manner on the graft, e.g. due to modification of graft tissue by culture, peripheral T cells of the recipient may ignore the graft. Alternatively, nonstimulatory presentation of donor antigens on graft tissue can induce a state of unresponsiveness in recipient T cells, i.e. anergy, rather than activating them to destroy the graft. Suppression mechanisms also operate to control graft rejection and may be specific or nonspecific in nature. Specific suppression mechanisms might act in an idiotype or antigen-specific fashion, and evidence is accumulating that this may be mediated through the elaboration of cytokines. Donor antigen-specific T cells may be activated to produce "protective" cytokines which then regulate the generation of destructive T cells. Future therapies will be aimed at affecting graft acceptance through these peripheral mechanisms.

Animals↗
PubMed1994

Isolation of nonobese diabetic mouse T-cells that recognize novel autoantigens involved in the early events of diabetes.

Insulin-dependent diabetes mellitus (IDDM) is thought to result from chronic, cell-mediated, autoimmune islet damage. Our aim was to identify the earliest T-cell autoantigen in IDDM, reasoning that this antigen could be causally involved in the initiation of the disease. Identification of the earliest beta-cell-specific autoantigen is extremely important in allowing advances in prevention and treatment of initial events in the development of inflammatory insulitis that precedes beta-cell destruction and overt diabetes. Therefore, we analyzed the proliferative responses of peripheral T-cells from young, female nonobese diabetic (NOD) mice to extracts of pancreatic beta-cell lines. We were able to demonstrate that T-cells responsive to beta-cell antigens exist in the peripheral lymphoid tissue of these mice in the absence of deliberate priming before the manifestation of histologically detectable insulitis. T-cell lines and clones isolated from the peripheral lymphatic tissues of young, unimmunized, female NOD mice were also shown to react with extracts of beta-cells. Fractionation of the beta-cell extracts showed that these T-cell clones recognized multiple beta-cell-specific autoantigens but none of the previously reported putative autoantigens (glutamic acid decarboxylase [GAD]65, GAD67, Hsp65, insulin, ICA 69, carboxypeptidase-H, and peripherin). Thus, we can conclude that these responses are specific for novel beta-cell autoantigens. Finally, NOD T-cell proliferative responses were also seen to an extract of human islets suggesting potential shared antigenic determinants between human and mouse beta-cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1993

Selection for amino acid sequence and J beta element usage in the beta chain of DBA/2V beta b- and DBA/2V beta a-derived myoglobin-specific T cell clones.

Previous experiments in our laboratory have demonstrated that there is a marked restriction on the TCR beta-chain usage in DBA/2 mice in response to the sperm whale myoglobin (SpWMb) determinant 110-121, predominated by the use of the V beta 8.2 gene element. We analyzed the response of mice that had been genetically depleted of V beta 8+ T cells by generating a DBA/2 line that carries the V beta a TCR haplotype. Despite the very limited TCR repertoire expressed by DBA/2V beta a mice, they made an excellent response after immunization with the SpWMb 110-121 peptide. Data presented in this manuscript demonstrate that there is an equally restricted TCR V beta-chain utilization in the T-cell response to the determinant SpWMb 110-121 in DBA/2V beta a mice. Unexpectedly, there was a shift of MHC restriction of this determinant to T cells in the V beta a strain when compared with the V beta b strain of DBA/2 mice. We had previously demonstrated that DBA/2 mice utilized both the hybrid E alpha dA beta d MHC molecule as well as the conventional A alpha dA beta d molecule as presenting elements in response to SpWMb 110-121. Data presented in this manuscript demonstrate that the T-cell response in DBA/2V beta a mice is entirely restricted by the A alpha dA beta d MHC class II molecule. By analyzing a panel of SpWMb 110-121-specific T-cell clones from DBA/2V beta a mice, we were able to study the TCR repertoire expressed on T cells from mice that lack the V beta 8.2 gene. The V beta usage by the panel of clones analyzed was remarkably homogeneous. Thirteen of the 17 clones analyzed used the V beta 1 gene segment. Perhaps more striking was the junctional region nucleotide and amino acid sequences that were shared among these clones and that were similar to the V beta 8.2 clones analyzed previously. All clones assayed used the J beta 2.6 element, as did the great majority of the V beta 8.2 clones analyzed from DBA/2 (and B10.D2) V beta b mice. Importantly, in each strain of mice, irrespective of the V beta utilized, each TCR appeared to have selected an acidic amino acid in the beta-chain at position 100.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1993

Induction of relapsing paralysis in experimental autoimmune encephalomyelitis by bacterial superantigen.

The role of infection in the pathogenesis of clinical relapses that occur in most autoimmune diseases, including multiple sclerosis, remains to be established. Experimental autoimmune encephalomyelitis (EAE) serves as a model for multiple sclerosis, with episodes of relapsing paralysis. In certain strains of mice, T-lymphocytes expressing the V beta 8 T-cell receptor (TCR) engage the amino-terminal epitope Ac1-11 of myelin basic protein, leading to EAE. The bacterial superantigen staphylococcal enterotoxin B (SEB) activates V beta 8-expressing T cells. Here we show that after immunization with Ac1-11, or after transfer of encephalitogenic T-cell lines or clones reactive to Ac1-11, SEB induces exacerbation or relapses of paralytic disease in mice that are in clinical remission following an initial episode of paralysis, and triggers paralysis in mice with subclinical disease. Tumour necrosis factor has a critical role in the mechanism underlying SEB-induced exacerbation of disease, because anti-tumour necrosis factor antibody given in vivo delays the onset of paralysis triggered by SEB. On reactivation of autoaggressive cells through their T-cell receptor, superantigens may induce clinical relapses of autoimmune disease.

Amino Acid Sequence↗
PubMed1993

SEB induced anergy: modulation of immune response to T cell determinants of myoglobin and myelin basic protein.

Superantigens have the ability to stimulate a subset of T cells based upon their expressed TCR beta-chain. It has been demonstrated that the administration of staphylococcal enterotoxin B (SEB) in mice leads to unresponsiveness in V beta 8+ T cells in vivo which are the same T cells that could be stimulated in vitro by this enterotoxin. We present here data on the effect of SEB administration in DBA/2 and (PL/J x SJL)F1 mice on their T cell response to two different T cell determinants, the responses against which are dominated by the use of V beta 8+ T cells. Treatment of mice with SEB not only diminished their primary T cell proliferative response to these determinants, but also was able to effectively reduce the memory T cell response. SEB treatment, however, showed only a modest effect in preventing Ac 1-11-induced experimental autoimmune encephalomyelitis in H-2u mice.

Amino Acid Sequence↗
PubMed1993

Requirement for CD8+ cells in T cell receptor peptide-induced clonal unresponsiveness.

T cell receptor (TCR) vaccination in rats prevents the development of experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis. The mechanism of this potential immunotherapy was examined by vaccinating mice with an immunogenic peptide fragment of the variable region of the TCR V beta 8.2 gene. Another immunogen that usually induces an immune response mediated by V beta 8.2+ T cells was subsequently inhibited because specific clonal unresponsiveness (anergy) had been induced. Depletion of CD8+ cells before TCR peptide vaccination blocked such inhibition. Thus, the clonal anergy was dependent on CD8+ T cells, and such immunoregulatory T cells may participate in the normal course of EAE.

Animals↗
PubMed1993

Evidence that anti-CD8 abrogates anti-CD4-mediated clonal anergy but allows allograft survival in mice.

Monoclonal antibodies directed against different T cell subpopulations have been used in several rodent models of transplantation to induce long-term unresponsiveness to allografts by a variety of mechanisms. To investigate whether different mechanisms may be operative when different regimens of mAb therapy are used, we studied the effects of various combinations of anti-T-cell antibody treatment on the induction of tolerance in a mouse islet allograft model. Anti-CD4 mAb alone, anti-CD8 mAb alone, anti-CD4 mAb plus anti-CD8 mAb, and anti-Thy1.2 mAb alone were given at the time of engraftment. Only the anti-CD4 mAb and the anti-CD4 mAb plus anti-CD8 mAb regimens were successful in inducing permanent unresponsiveness to islet allografts. We have previously shown that anti-CD4 mAb alone induces permanent unresponsiveness to islet allografts by a mechanism of clonal anergy, as demonstrated by unresponsiveness of potentially alloreactive T cells to anti-T-cell receptor-specific cross-linking. Interestingly, the potentially alloreactive T cell subsets of recipient mice (V beta 5+ and V beta 11+) made unresponsive to islet allografts by anti-CD4 mAb plus anti-CD8 mAb therapy were not found to be anergic using the same assay. Differences between the repopulation kinetics of CD8+ T cells of anti-CD4 mAb plus anti-CD8 mAb treated recipient mice, which accepted islet allografts, and anti-Thy1.2 treated recipient mice, which rejected islet allografts despite similar levels of initial T cell depletion, suggest that unresponsiveness to alloantigen may have been induced in anti-CD4 mAb plus anti-CD8 mAb treated recipients by clearance of donor passenger leukocytes during prolonged CD8+ T cell depletion.

Animals↗
PubMed1993

The use of granzyme A as a marker of heart transplant rejection in cyclosporine or anti-CD4 monoclonal antibody-treated rats.

Granzyme A is a serine protease expressed by populations of human and mouse natural killer cells and activated CD4+ and CD8+ cytotoxic lymphocytes; its expression marks a subset of inflammatory cells in allografts, autoimmune diabetes, and a number of other inflammatory lesions. In order to describe more completely the correlation between granzyme A expression and the presence of in vivo cytolytic effects, we grafted allogeneic rat hearts with vascular anastomoses in a heterotopic location, and treated the hosts with either cyclosporine, anti-CD4 monoclonal antibody (MRC OX38), or no therapy. The grafts were evaluated by palpation for cardiac functions, by immunohistochemistry for CD4/CD8 expression, by hematoxylin-and-eosin staining for inflammatory infiltration, and by in situ hybridization for granzyme A expression. The appearance of granzyme A+ cells in untreated allografts preceded both functional and standard histopathological and immunohistochemical evidence of graft rejection by two days. In donor-recipient combinations where cyclosporine and anti-CD4 treatments allowed indefinite allograft survival, the allografts showed minimal numbers of granzyme A+ cells, whether cellular infiltrates developed or not. The number of granzyme A+ cells present in the cardiac allografts in treated and untreated animals correlated with either current or impending episodes of rejection. The early time course of granzyme A expression suggests that it can be used as an early and reliable marker of graft rejection.

Animals↗
PubMed1993

Evidence that clonal anergy is induced in thymic migrant cells after anti-CD4-mediated transplantation tolerance.

Diabetic (B6) (IE-) mice treated with a depleting regimen of anti-CD4 monoclonal antibody at the time of transplantation with A/J (IEK) islets of Langerhans showed indefinite acceptance of their islet allograft, as evidenced by persistent normoglycemia. To address the mechanisms involved in such anti-CD4 induced transplantation tolerance we studied potentially IE-reactive V beta 11+ T cells from the tolerant allografted mice. Following complete repopulation of the CD4+ cells, both the CD4+V beta 11+ and CD8+V beta 11+ T cell subsets of the transplanted mice were unresponsive to anti-V beta 11 specific crosslinking. In contrast, lymphocytes tested within the first ten days following transplant were responsive to anti-V beta 11 specific crosslinking; this response decreased as a function of time and reached background levels by day 120 posttransplant. Sorting experiments indicated that the response of lymphocytes to anti-V beta 11 specific crosslinking seen during the initial 120 days posttransplant was confined to the peripheral CD8+ cells; the repopulating CD4+V beta 11+ T cells were unresponsive. In addition, administration of r-IL-2 at the time of transplantation induced rejection in anti-CD4-treated animals, again indicating that the peripheral CD8+ cells could respond shortly after transplant if provided with appropriate help. The decreasing response of CD8+ T cells from transplanted animals to anti-V beta 11 stimulation was inversely correlated with the rate of migration of cells from the thymus to the periphery, implying that new thymic migrant V beta 11+ cells, both CD4+ and CD8+, were rendered anergic upon encountering peripheral alloantigen. These data suggest the possibility that recent thymic migrants are rendered anergic upon encountering antigen in the periphery, a simple model to serve as a "fail-safe" mechanism to prevent autoreactivity.

Animals↗
PubMed1992

Amelioration of autoimmune encephalomyelitis by myelin basic protein synthetic peptide-induced anergy.

Experimental autoimmune encephalomyelitis (EAE), a demyelinating disease of the central nervous system that can be induced in susceptible strains of mice by immunization with myelin basic protein (MBP) or its immunodominant T cell determinants, serves as a model of human multiple sclerosis. Tolerance to MBP in adult mice was induced by intraperitoneal injection of synthetic peptides of immunodominant determinants of MBP and prevented MBP-induced EAE. Furthermore, tolerance-inducing regimens of peptides administered to mice after the disease had begun (10 days after induction with MBP) blocked the progression and decreased the severity of EAE. Peptide-induced tolerance resulted from the induction of anergy in proliferative, antigen-specific T cells.

Animals↗
PubMed1992

Limited T cell receptor beta-chain usage in the sperm whale myoglobin 110-121/E alpha dA beta d response by H-2d congenic mouse strains.

The specificity and TCR gene usage of a panel of sperm whale myoglobin (SpWMb)-reactive T cell clones from DBA/2 mice have previously been characterized, to study structure-function relationships between components of the ternary complex consisting of Ag, TCR, and MHC class II molecules, whose interaction leads to Th cell activation. These DBA/2 clones were specific for epitopes within the residue 110 to 121 region of SpWMb, in the context of the mixed isotype molecule E alpha dA beta d, and expressed the TCR V beta 8.2 gene element. SpWMb-specific T cell hybridomas from the H-2d-congenic B10.D2 mouse strain, which differs from the DBA/2 strain only in the non-MHC background, were generated and compared with the T cell hybridomas from DBA/2 mice, in order to investigate the influence of non-MHC genes on the specificity of the T cell response to the 110-121 epitope. V beta usage by these hybridomas was very homogeneous; three of three DBA/2 and eight of nine B10.D2 hybridomas specific for the 110-121 epitope, in the context of the mixed isotype molecule E alpha dA beta d, expressed the V beta 8.2 gene product. Nucleotide and amino acid sequences of D beta, J beta, and N regions were also similar. One 110-121/E alpha dA beta d-specific B10.D2 hybridoma used V beta 7, a V beta that is clonally deleted in DBA/2 mice. These experiments suggest that a similar set of TCR beta genes are used to respond to a given epitope, regardless of non-MHC background, and they support the hypothesis that, despite great variability between individuals in their non-MHC background genes, human HLA-associated diseases might result from the formation of a particular ternary complex consisting of a shared MHC molecule, a common "disease-associated" epitope, and a shared TCR.

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