A disaccharide that inhibits tumor necrosis factor alpha is formed from the extracellular matrix by the enzyme heparanase

The activation of T cells by antigens or mitogens leads to the secretion of cytokines and enzymes that shape the inflammatory response. Among these molecular mediators of inflammation is a heparanase enzyme that degrades the heparan sulfate scaffold of the extracellular matrix (ECM). Activated T cells use heparanase to penetrate the ECM and gain access to the tissues. We now report that among the breakdown products of the ECM generated by heparanase is a trisulfated disaccharide that can inhibit delayed-type hypersensitivity (DTH) in mice. This inhibition of T-cell mediated inflammation in vivo was associated with an inhibitory effect of the disaccharide on the production of biologically active tumor necrosis factor alpha (TNF-alpha) by activated T cells in vitro; the trisulfated disaccharide did not affect T-cell viability or responsiveness generally. Both the in vivo and in vitro effects of the disaccharide manifested a bell-shaped dose-response curve. The inhibitory effects of the trisulfated disaccharide were lost if the sulfate groups were removed. Thus, the disaccharide, which may be a natural product of inflammation, can regulate the functional nature of the response by the T cell to activation. Such a feedback control mechanism could enable the T cell to assess the extent of tissue degradation and adjust its behavior accordingly.

The proteoglycan perlecan is expressed in the erythroleukemia cell line K562 and is upregulated by sodium butyrate and phorbol ester

Perlecan is a modular heparan sulfate proteoglycan that harbors five domains with homology to the low density lipoprotein receptor, epidermal growth factor, laminin and neural cell adhesion molecule. Using a monoclonal antibody directed against the laminin-like domain of perlecan, we have recently shown that perlecan is widely expressed in all lymphoreticular systems. To investigate further this observation we have studied the expression of perlecan in two human leukemic cell lines. Using reverse transcriptase-PCR, ribonuclease protection assay, and metabolic labeling we detected significant perlecan expression in the multipotential cell line K562, originally derived from a patient with chronic myelogenous leukemia. In contrast, the promyelocytic cell line HL-60 expressed perlecan at barely detectable levels. These results were intriguing because the K562 cells do not assemble or produce a classical basement membrane. Following induction with either sodium butyrate or the phorbol diester 12-0-tetradecanoylphorbol-13-acetate (TPA), K562 and HL-60 differentiate into early progenitor cells with erythroid or megakaryocytic properties, respectively. Following treatment of K562 and HL-60 cells with either of these agents, perlecan expression was markedly increased in K562 cells. In contrast, we could detect perlecan protein synthesis in HL-60 cells only at very low levels, even after induction with TPA or sodium butyrate. Collectively, these results indicate that perlecan is actively synthesized by bone marrow derived cells and suggest that this proteoglycan may play a role in hematopoietic cell differentiation.

A quantitative model of autoimmune disease and T-cell vaccination: does more mean less?

According to a simple mathematical model, the activated effector T cells that cause an autoimmune disorder can also cure the disease if administered in large doses. This prediction has been tested in the nonobese diabetic (NOD) mouse model and demonstrates that administration of intermediate doses of a diabetogenic T-cell clone caused early hyperglycemia, whereas a higher dose cured the disease. As discussed here by Lee Segel and colleagues, the proposed application of T-cell vaccination to treat clinical disease obliges immunologists to consider the quantitative complexities of regulation.

Abnormal expression of perlecan proteoglycan in metastatic melanomas

Abnormal expression of proteoglycans has been implicated in cancer and metastasis primarily because these macromolecules are involved in the control of cell growth and matrix assembly. In this report, we have investigated the expression and immunolocalization of perlecan, a major heparan sulfate proteoglycan of basement membranes and pericellular matrices, in human metastatic melanomas. Twenty-six of the 27 tumor samples showed a significant increase (up to 15-fold) in the perlecan mRNA levels when compared with normal tissue. This change correlated with a vast deposition of perlecan protein core in the pericellular matrix of metastatic melanomas. Furthermore, we have established a relationship between perlecan expression in clonal melanoma cells (70W) stimulated with neurotrophins and their increased invasiveness. Interestingly, perlecan mRNA levels were up-regulated within 10 min of neurotrophin stimulation, indicating that perlecan is an early response gene. This upregulation also occurred prior to heparanase production, suggesting that perlecan expression and its regulation might play a pivotal role in the initial onset of invasion.

Expression of major histocompatibility complex class II molecules in rat T cells

The expression of major histocompatibility complex (MHC) class II molecules in murine T cells has been controversial. We therefore reexamined the transcription, synthesis and surface expression of MHC class II determinants in rat T cells both in vivo and in vitro. In naive rats, a large proportion of small CD4+8+ and mature CD4+8-/CD4-8+ thymocytes was found to be MHC class II positive. At least some of the MHC class II molecules found on thymocytes were actively synthesized. The synthesis of MHC class II proteins was detected in peripheral T cells activated in vivo during induction of experimental allergic encephalomyelitis (EAE). A proportion of T cells from the inflammatory lesion of EAE exhibited MHC class II on the surface. A panel of helper T cell lines and clones was shown to synthesize MHC class II proteins. In a prototypic clone, a weak constitutive expression of MHC class II was observed. During activation, the rate of endogenous MHC class II synthesis increased and passive absorption of surface MHC class II from other cells occurred. Our data demonstrate the expression of MHC class II molecules in rat T cells in both the thymus and periphery. Since the primary function of MHC class II molecules is the presentation of peptide epitopes to T cells, these results call attention to the possible role of MHC class II molecules in T-T interactions during T cell maturation and activation.

Intravenous gammaglobulin treatment in multiple sclerosis and experimental autoimmune encephalomyelitis: delineation of usage and mode of action

Multiple sclerosis (MS) is a central nervous system demyelinating disease of implicated autoimmune aetiology. The effect was evaluated of intravenous gammaglobulin (IVIg), a successful therapy in various autoimmune diseases, in relapsing-remitting MS patients treated for three years. IVIg treatment significantly reduced the number and severity of acute exacerbations and resulted in a lesser neurological disability. There were no significant short or long-term adverse effects to IVIg treatment. To clarify the putative therapeutic effects of IVIg, this treatment was examined in the animal model of experimental autoimmune encephalomyelitis (EAE) in the rat. IVIg suppressed active EAE in relation to disease severity and duration, despite the presence of T-cell reactivity to specific antigens, while the treatment had no effect on passive EAE induced by adoptive transfer of myelin basic protein specific CD4 + T-cells. It is concluded that IVIg treatment may be a promising treatment in relapsing-remitting MS as it can alter the natural course of the disease.

Low doses of low molecular weight heparin in vivo inhibits the elicitation of contact hypersensitivity

Low-dose low molecular heparin inhibits T lymphocyte-mediated autoimmune disease and allograft reactions in mice in vivo and in vitro. High doses of heparin are not effective. The purpose of this preliminary study was to analyze the effect of low-dose, low molecular weight heparin (Enoxaparin, Clexane) on the expression of patch testing in patients with contact dermatitis. Eleven patients with allergic contact dermatitis, and positive patch tests reactions, were given a single subcutaneous injection of Clexane 3 mg (0.03 ml) and were reevaluated for positive reactions after the injection. Eight out of 21 positive reactions (38%) became negative after the injection and 4 out of 21 reactions (19%) changed from ++ before the injection to + after. An impressive improvement was observed in 3 patients with chronic allergic contact dermatitis. Low-dose low molecular weight heparin inhibits the elicitation of allergic contact dermatitis.

The biology of perlecan: the multifaceted heparan sulphate proteoglycan of basement membranes and pericellular matrices

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Autoimmune diabetes induced by the beta-cell toxin STZ. Immunity to the 60-kDa heat shock protein and to insulin

Administered at a suitably low dose, the toxin streptozotocin (STZ) can trigger an autoimmune process leading to destruction of the beta-cells of the pancreatic islets. In this study, we examined specific immunological reactions in mice before and during the development of STZ-induced autoimmune diabetes. We now report that the development of spontaneous autoantibodies to insulin can serve as a marker of susceptibility to a low dose of STZ. Susceptible male mice of the C57BL/KsJ strain manifested such anti-insulin antibodies, and resistant female mice did not. Administration of a low dose of STZ (five daily doses each of 30 mg/kg) induced transient hyperglycemia approximately 20-30 days later, which temporarily remitted but was followed by intractable diabetes approximately 2.5 months later. The diabetogenic process triggered by the low dose of STZ was associated with an increase in the level of anti-insulin antibodies bearing the Dana and Micha (DM) idiotype, later followed by the appearance of anti-idiotypic antibodies that peaked before the onset of diabetes. Antibodies and T-cells reactive to hsp60 (heat shock protein) were triggered by the low-dose STZ administration and persisted throughout the period that preceded clinical diabetes. T-cells reactive to the p277 peptide of hsp60 were also observed. Finally, active immunization to hsp60 caused transient hyperglycemia by itself and also aggravated the hyperglycemia induced by low-dose STZ. Thus, autoantibodies to insulin can indicate susceptibility to a toxic trigger of diabetes, and a low dose of a toxin can activate the insulin and hsp60 autoimmunity that has been detected previously in the spontaneous autoimmune diabetes of NOD strain mice.

T cell immunity to myelin basic protein induces anterior uveitis in Lewis rats

Uveitis of unknown etiology is known to occur in association with various systemic disorders. We now report that anterior uveitis (AU) can be produced by T cell immunity to myelin basic protein (BP) and accompanies experimental autoimmune encephalomyelitis (EAE). EAE with AU was induced in Lewis rats by immunization to BP in CFA or by immunization to various BP peptides including the encephalitogenic 71-90 peptide. Slit-lamp biomicroscopy of BP-immunized Lewis rats revealed AU, characterised by inflammation of the iris, in 73% of the eyes. The onset of AU in actively immunized rats varied between days 12 and 26, often appearing after spontaneous remission of the paralysis, the hallmark of EAE. The course of AU was progressive, affecting more than 50% of the surface of the iris in 16 of 29 diseased eyes. Like the paralysis, the AU was self-limiting: within 2 weeks the disease remitted. In addition, AU could be adoptively transferred to naive and irradiated rats by a T cell clone specific for BP peptide 71-90. The present observations are compatible with the idea that AU may be triggered by BP-reactive T cells. The myelinated nerves present in the iris have been shown to contain BP. However, these peripheral nerves would now appear to be the only peripheral nerves susceptible to acute EAE.

Peptide therapy for diabetes in NOD mice

NOD mice spontaneously develop autoimmune diabetes that mimics insulin-dependent diabetes mellitus (IDDM) in man. A peptide of the 60 kDa heat shock protein (hsp60), designated p277, can serve as a target for diabetogenic T-cell clones, and diabetes was prevented by using the p277 peptide to turn off anti-p277 immunity early in life. We report that the p277 peptide, administered once, can arrest the autoimmune process even after it is far advanced. Successful therapy was associated with down-regulation of the autoimmune process and regression of islet inflammation. Thus the immune system is responsive to manipulation by a specific signal even in the face of a virulent, full-blown autoimmune process.

Intravenous immunoglobulin treatment of experimental T cell-mediated autoimmune disease. Upregulation of T cell proliferation and downregulation of tumor necrosis factor alpha secretion

It has been reported previously that intravenous administration of normal human immunoglobulins (IVIg) to human patients can suppress the clinical signs of certain autoimmune diseases. However, the mechanism(s) by which normal Ig interferes with the various disorders and the scheduling of treatment have been poorly delineated. To study these questions, we examined IVIg treatment of two experimentally induced T cell autoimmune diseases in rats: experimental autoimmune encephalomyelitis (EAE) and adjuvant arthritis (AA). We now report that IVIg treatment (0.4 g/kg) inhibited the active induction of both EAE and AA, and that this treatment did not affect the acquisition of resistance to reinduction of EAE. The importance of the site of administration and schedule of treatment were studied in the AA model. Ig was effective when given intravenously, but not when administrated subcutaneously or intraperitoneally. IVIg treatment was effective when given daily from immunization to outbreak of disease; but it was also effective when given once at the time of immunization or once 2 wk after induction of AA, just at the clinical outbreak of disease. Administration of IVIg between immunization and outbreak of AA was less effective. Prevention of disease by IVIg occurred despite the presence of T cell reactivity to the specific antigens in the disease. In fact, IVIg administrated to naive rats activated T cell reactivity to some self-antigens. Nevertheless, IVIg treatment led to decreased production of the inflammatory cytokine TNF alpha. Thus, IVIg treatment may exert its therapeutic power not by inhibiting T cell recognition of self-antigens, but by inhibiting the biological consequences of T cell recognition.

Protection of mice against mycobacterial infection by lymphoid cell vaccination

Intracellular parasites may thrive by inducing the host's immune system to suppress the effector immune response that otherwise limits multiplication. Hosts are traditionally immunized with the parasite antigens that induce effector immunity. Alternatively, one might vaccinate the host with the host lymphoid cells involved in suppression. Multiplication of Mycobacterium marinum was prevented by vaccinating mice with cells prepared from the popliteal lymph nodes of mice in which the organisms were multiplying logarithmically, that were inactivated by fixation with glutaraldehyde. Cells obtained later during infection, when the donor mice manifest immunity, did not protect against infection. Thus, it may be possible to influence the course of a microbial infection by immunizing the host not only with components of the organisms, but also with the host components that are exploited by the organism.

T-cell autoimmunity in type 1 diabetes mellitus

Insulin dependent diabetes mellitus is a T-cell mediated autoimmune disease. Several beta-cell antigens, mostly non-tissue-specific, have been implicated in the disease process. The antigens and the autoimmune T cells exist in healthy individuals, as do many of the genes required for the development of diabetes. The question, then, is why and how exposure to undefined environmental agents activates an existing autoimmune potential and directs it to damage the beta cells.

Adjuvant arthritis is associated with changes in the glycosylation of serum IgG1 and IgG2b

The increased amounts of agalactosyl IgG (N-linked oligosaccharides terminating with N-acetylglucosamine (GlcNAc) in the serum of patients with rheumatoid arthritis (RA) and other chronic inflammatory diseases have suggested that agalactosyl IgG may be involved in the pathogenesis of RA. We have now evaluated the incidence of agalactosyl IgG in the Lewis rat during the course of adjuvant arthritis (AA). The modification in glycosylation of IgG was measured by means of polyclonal and monoclonal anti GlcNAc antibodies as well as by the lectin concanavalin A (Con A). The results show that Lewis rats undergo a change in serum IgG glycosylation during the course of AA. As in human RA patients, rats with AA lack terminal galactose on IgG heavy chain oligosaccharides, and the terminal GlcNAc or mannose residues are thus exposed. The degree of agalactosyl IgG was positively correlated with the incidence of disease, peaked 20 days after disease induction, and the IgG gradually reverted to the fully glycosylated form thereafter. The post-arthritic glycosylation profile was very similar to that characteristic of the naive animal. Purified IgG was shown to contain two IgG subclasses, IgG1 and IgG2b, which underwent changes in glycosylation. Western blot analysis revealed that IgG1 expressed a higher degree of terminal mannose, whereas IgG2b expressed a higher degree of terminal GlcNAc. These findings raise the question of the possible involvement of agalactosyl IgG in immune complex-mediated inflammation.

Shifts in the epitopes of myelin basic protein recognized by Lewis rat T cells before, during, and after the induction of experimental autoimmune encephalomyelitis

An epitope present in the 71-90 sequence of basic protein (BP) has been identified as the dominant epitope recognized by most Lewis rat encephalitogenic T cells isolated during experimental autoimmune encephalomyelitis (EAE). In the present study, we investigated the BP epitopes recognized by Lewis rat T cells in naive rats, in rats suffering from acute EAE, and in recovered rats. T cells isolated from the spinal cord lesions and from the lymph nodes were studied using T cell lines and bulk cultures. Virulence of the T cells was assayed by adoptive transfer. We now report that naive and recovered Lewis rats are populated with T cells reactive to a variety of BP epitopes and only a minority are specific for the 71-90 epitope. In contrast, the induction of EAE was associated with a predominance of T cells reactive to the 71-90 epitope. T cells recovered from naive, diseased, or recovered rats were found to be virulent upon passive transfer. Some of these virulent T cells were specific to BP epitopes other than the 71-90 epitope. There was no major difference in the BP specificities of T cells isolated from the lesions and from the lymph nodes. Thus, natural T cell reactivity to BP is heterogeneous and pathogenicity is not confined to one particular epitope, active disease is characterized by a dominant response to the 71-90 epitope, and recovery is marked by a return to heterogeneity.

Effects of the serotonin antagonist amesergide on reproduction in female rats

Amesergide, a serotonin (5-HT2) antagonist intended to treat depression, was administered orally to female CD rats (20/group) at doses of 0, 3, 10, or 30 mg/kg to evaluate effects on mating, fertility, litter size, live birth index (100 x total liveborn progeny/litter size), progeny survival, and weight gain of each litter. The treatment period extended from two weeks prior to mating through postpartum day 21 to cover possible effects of estrous cycle, mating, gestation, and postpartum events. Twenty additional female rats were given 30 mg/kg through gestation day 18, after which they received the acacia vehicle (recovery group). All females were allowed to deliver naturally and rear their progeny. On postpartum day 8, progeny in the control, 30 mg/kg and 30 mg/kg recovery groups were removed from dams for 4 h. Progeny were weighed as litters, returned to the dams for a 1-h nursing period, and then weighed again to provide an indication of milk intake. Mating and fertility, using the present study design, were not affected by treatment with amesergide. No effects were observed on litter size, live birth index, or progeny survival. In contrast, treatment with amesergide throughout gestation and lactation produced a significant dose-related depression in progeny body weight gains. However, when treatment was discontinued after day 18 of gestation (30 mg/kg recovery group), progeny body weight gains did not differ from those of the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural characterization of the complete human perlecan gene and its promoter

The complete intron-exon organization of the gene encoding human perlecan (HSPG2), the major heparan sulfate proteoglycan of basement membranes, has been elucidated, and specific exons have been assigned to coding sequences for the modular domains of the protein core. The gene was composed of 94 exons, spanning > 120 kbp of genomic DNA. The exon arrangement was analyzed vis-à-vis the modular structure of the perlecan, which harbors protein domains homologous to the low density lipoprotein receptor, laminin, epidermal growth factor, and neural cell adhesion molecule. The exon size and the intron phases were highly conserved when compared to the corresponding domains of the homologous genes, suggesting that most of this modular proteoglycan has evolved from a common ancestor by gene duplication or exon shuffling. The 5' flanking region revealed a structural organization characteristic of housekeeping and growth control-related genes. It lacked canonical TATA or CAAT boxes, but it contained several GC boxes with binding sites for the transcription factors SP1 and ETF. Consistent with the lack of a TATA element, the perlecan gene contained multiple transcription initiation sites distributed over 80 bp of genomic DNA. These results offer insights into the evolution of this chimeric molecule and provide the molecular basis for understanding the transcriptional control of this important gene.

Low-dose heparin inhibits acute graft versus host disease in mice

We have studied the effect of low-dose heparin on GVHD, marrow engraftment and graft-versus-leukemia (GVL) effects in an experimental murine model. Recipient (C57BL/6 x BALB/c) F1 mice were transplanted with C57BL/6 marrow and/or spleen cells and treated with daily sc injection of 5 micrograms heparin for 30 days. We have shown that heparin in low doses attenuates the severity of acute GVHD and reduces the mortality rate from 69 to 37.5% without abrogating the GVL effect induced by the allograft and without impairing marrow engraftment.

Induction of the anti-ergotypic response

The injection of syngeneic activated T cells into rodents can induce a T cell response against activation markers of the T cells, ergotopes. The responding anti-ergotypic T cells have been shown to suppress experimental autoimmune encephalomyelitis (EAE). This paper reports the characteristics of the anti-ergotypic response. It was found that irradiated activated T cells were as good as untreated living activated T cells in inducing anti-ergotypic cells in vivo. Glutardialdehyde-fixed (0.3%) cells were poor stimulators in vivo and non-stimulatory in vitro. Dilution of glutardialdehyde to 0.003% before fixation preserved the stimulatory capacity in vitro. Fixation or irradiation of T cells at different times after activation showed that the stimulatory ergotope appears only after more than 12 h of activation. This ergotope is not secreted by activated T cells, but is a structural component of the activated T cell. Injection of solubilized proteins from activated T cells, but not of supernatants from activated T cells, was able to induce an anti-ergotypic response in vivo. In vitro supernatants from activated T cells also were not stimulatory to anti-ergotypic T cells. The anti-ergotypic response could be measured in draining lymph nodes 3 days after injection, reached a maximum after 7-10 days and subsided thereafter. It was earlier and stronger than the anti-idiotypic response. Induction of the response was dose dependent. As few as 100 cells were able to induce a marked anti-ergotypic response. The ease of the induction and the strength of the anti-ergotypic response suggest a physiological role in immunoregulation.

Effects of inoculation with attenuated autologous T cells in patients with rheumatoid arthritis

Injection of attenuated autoimmune T cells, T cell vaccination, has been used successfully in the prevention and treatment of experimental animal autoimmune disease. In order to determine whether such a procedure might be applied in rheumatoid arthritis (RA), a phase I study was conducted in thirteen RA patients with a mean disease duration of 12.8 years. All patients received a subcutaneous injection of attenuated autologous T lymphocytes from a CD4 positive clone (n = 4) or line (n = 9) isolated from synovial tissue (n = 3) or synovial fluid (n = 10). No toxic side effects were observed. On the average the patients showed a slight decrease in disease activity which was most marked at 8 weeks after the injection. Specific immune reactivity against the injected T cells was not detected, with the possible exception of one patient who was vaccinated with a clone selected in vitro with antigen and whose disease had begun one year earlier. In this patient a clear decrease in disease activity occurred, which was associated with a decrease in mitogen-induced proliferation of her peripheral blood mononuclear cells and in titres of serum rheumatoid factors. The results of this study show that inoculation of RA patients with autologous T cells is technically feasible and non-toxic, and may be associated with clinical and immunological effects. The data suggest that the potential of T cell vaccination should be further explored in diseases with defined antigen reactivity.

Experimental aspects of T cell vaccination

In the last 10 years, our laboratory has investigated the role of T cells in the induction and therapy of experimental autoimmune diseases. In several animal model T cell lines and clones that were expanded in vitro by repeated culture with the autoantigen were found to be pathogenic. Inoculation of pathogenic T cells after attenuation resulted in protection of the animals against a future attempt to induce the disease: this form of therapy was termed T cell vaccination (TCV). Several forms of TCV were developed, including the administration of T cell lines attenuated by irradiation or mitomycin C, membrane modified cells and sub-pathogenic doses of unmodified T cells. The vaccinating effect was found to be mediated by T cells. Vaccinated animals had both CD4 T cells that responded to the vaccine and CD8 T cells that suppressed its response to the autoantigen. The major obstacle to the clinical application of TCV in human autoimmune diseases is the fact that the nature of autoantigens initiating and perpetuating the disease are not known.

Prolongation of survival of rat cardiac allografts by T cell vaccination

Administration of attenuated, activated autoimmune T lymphocytes to syngeneic mice and rats has been shown to prevent or induce remission of experimental autoimmune diseases specific for the autoimmune T cells. The process has been termed "T cell vaccination." In a recent study, T cell vaccination was done using T cells sensitized to rat alloantigens. The procedure produced a significant reduction of the mixed lymphocyte reaction (MLR) against allogeneic cells. The reduction in MLR was not specific: Vaccination with T cells specific for stimulator cells of one allotype led to a reduced MLR stimulated by cells of another allotype. The present study was undertaken to examine whether T cell vaccination can induce tolerance to transplantation antigens in vivo. We used the model of heterotopic cardiac transplantation in rats. We now report that vaccinating rats with syngeneic, activated, alloantigen-primed T lymphocytes significantly prolonged survival of rat cardiac allografts. The effect of T cell vaccination was most evident when the T cells had been obtained from rats specifically sensitized against the donor rats: Brown-Norway (BN) allografts in control Wistar rats survived 8.5 +/- 0.4 d while BN allografts survived 29.2 +/- 7.1 d in Wistar rats that had been vaccinated with Wistar anti-BN cells. Vaccination of Wistar rats with Wistar anti-hooded T cells prolonged survival of BN heart allografts to a lesser but significant degree (13.0 +/- 1.1 d). Thus, T cell vaccination of recipients can prolong survival of allografts.

Extracellular matrix induces tumour necrosis factor-alpha secretion by an interaction between resting rat CD4+ T cells and macrophages

T lymphocytes and macrophages (M phi) have been seen to accumulate at sites of lesions in blood vessel walls, suggesting that these cells may contribute to the pathogenesis of inflammatory reactions. Tumour necrosis factor-alpha (TNF-alpha), a cytokine produced by both M phi and T lymphocytes, plays a major role in inflammatory reactions, blood vessel formation, thrombosis and atherosclerosis. We now report that secretion of TNF-alpha by cloned CD4+ rat T cells, and to a lesser degree by peripheral T cells, and M phi can be induced in vitro in the absence of antigen, in a major histocompatibility complex (MHC) class II-independent manner by integrin-mediated recognition of immobilized components of extracellular matrix such as fibronectin and laminin; the secretion of TNF-alpha by the interacting resting cells on fibronectin was partially abrogated by the presence of the Arg-Gly-Asp (RGD)-containing amino acid sequence. This T cell-M phi interaction involves CD2 and CD4 molecules and requires a signal transduced in the T cells by a protein tyrosine kinase. Thus, a multicellular interaction with extracellular matrix protein exposed as a consequence of vascular wall injury can serve to signal the secretion of TNF-alpha which induces the recruitment of additional immune cells to the developing lesion.

On the regulation of EAE

This paper describes some of the factors involved in the regulation of EAE and of autoimmunity in general. The immunological homunculus is discussed.

The cognitive paradigm and the immunological homunculus

In last month's issue of Immunology Today, Irun Cohen discussed the inadequacies of the clonal selection paradigm and proposed a cognitive paradigm in which preformed internal images guide and restrict the process of clonal activation. Here he clarifies the nature of these internal images, during on concrete examples from the image of infection and the image of self, the immunological homunculus.

T cells in the lesion of experimental autoimmune encephalomyelitis. Enrichment for reactivities to myelin basic protein and to heat shock proteins

To characterize the cellular immune response in an autoimmune lesion, we investigated the accumulation of specific T cells in the central nervous system in actively induced experimental autoimmune encephalomyelitis (EAE) in Lewis rats, using a limiting dilution analysis (LDA) assay for T cells that proliferate in response to antigens. Lymphocytes isolated from the spinal cord infiltrate were compared with cells from the popliteal lymph nodes with respect to frequency of cells responding to basic protein (BP), mycobacterium tuberculosis (MT), the 65-kD heat shock protein (hsp65), allogeneic brown norway spleen cells, and concanavalin A. Additionally, we compared the BP frequency in acute EAE of cells from the spinal cord, peripheral blood, spleen and lymph nodes, and the spinal cord and lymph node after recovery from EAE. We found that acute EAE was associated with marked enrichment of BP-reactive T cells in the spinal cord relative to their frequency in the lymphoid organs and peripheral blood. The infiltrate was also enriched for T cells responding to hsp65; alloreactive T cells, in contrast, were not enriched. The frequency of BP reactive T cells in the spinal cord was highest at the peak of paralysis; however, BP-reactive T cells could still be detected at moderate frequencies after clinical recovery. We established BP- and Mycobacteria-reactive T cell lines from the spinal infiltrates that were CD4+ and TcR alpha beta +. Most of the BP lines were found to react to the major encephalitogenic epitope of guinea pig BP for rats (amino acids 71-90); these lines were found to mediate EAE in naive recipients. T cell lines recognizing other epitopes of BP were not encephalitogenic. All of the lines responsive to Mycobacteria recognized hsp65 or hsp70. These results indicating that the immune infiltrate in active EAE is enriched with cells responding to the autoantigen and to hsp65 were confirmed in EAE adoptively transferred by anti-BP T cell clone.

The cognitive principle challenges clonal selection

Here, Irun Cohen argues that the clonal selection paradigm is no longer a convenient paradigm for organizing thinking about the immune system. He contends that most immunologists now investigate questions for which the clonal selection paradigm makes no provision and that one of its major tenets is contradicted by the prevalence of natural autoimmunity. Instead, he proposes a cognitive paradigm.

Autoimmune thyroiditis (EAT) in genetically resistant mice mediated by a T cell line

Experimental autoimmune thyroiditis (EAT) can be induced in genetically susceptible strains of mice by immunization to mouse thyroglobulin (Tg). EAT also can be produced by administration of anti-mouse Tg T cell lines and clones. Previously we were able to raise virulent anti-Tg T cell lines from mice genetically susceptible to EAT. These virulent lines, upon attenuation, were able to vaccinate the susceptible mice against EAT. We now report the isolation of a virulent T cell line from C57BL/6 mice genetically resistant to EAT. The T cell line and its clones recognize a Tg epitope cross-reactive between mouse and bovine Tg. Unexpectedly, the virulent anti-Tg line attenuated in various ways failed to vaccinate C57BL/6 mice against EAT mediated by the line itself. These results shed some light on the regulation of autoimmunity.

Wound dressing activity mimicking infection on labeled leukocyte imaging

Although labeled leukocyte imaging is an extremely useful technique for the localization of infection, false-positive results in inflammatory conditions where no infection exists have been described. False-positive results secondary to bleeding have also been reported. The authors recently observed intense uptake of labeled cells in the wound dressings of two patients undergoing leukocyte imaging. Repeat imaging after the removal of these dressings confirmed that the activity seen was in the dressings and did not represent focal infection, as originally thought. Based on these observations, the authors think it prudent to remove such dressings before performing leukocyte imaging.

Juvenile rheumatoid arthritis patients manifest immune reactivity to the mycobacterial 65-kDa heat shock protein, to its 180-188 peptide, and to a partially homologous peptide of the proteoglycan link protein

Immune reactivity to the 65-kDa mycobacterial heat shock protein (hsp65) has been associated with arthritis in rats and humans. In this report we evaluated patients with juvenile rheumatoid arthritis for such immunity. A high proportion of affected children showed both antibody and T lymphocyte responses to hsp65 and to two related peptides: the nonapeptide 180-188 sequence of hsp65 and a partially homologous peptide of the cartilage proteoglycan link protein. The titer of circulating antibodies was generally higher in patients with clinically active disease. In contrast to the juvenile rheumatoid arthritis patients, patients with adult rheumatoid arthritis tended to have lower responses of their peripheral blood T lymphocytes to the whole hsp65 molecule. Moreover, the adult rheumatoid arthritis patients did not respond to the peptides. Thus, there appear to be immunological differences between juvenile and adult forms of rheumatoid arthritis related to hsp65 reactivity.

Antibodies to mycobacterial 65 kDa heat shock protein in systemic sclerosis (scleroderma)

It has been reported that immunity to the 65 kDa heat shock protein of Mycobacterium tuberculosis (MT-hsp65) not only accompanies rheumatoid arthritis (RA), but may also be characteristic of chronic inflammation. We now report serum antibodies to MT-hsp65 in 47% of systemic sclerosis (SSc), 38% of primary Raynaud's phenomenon (PRP) and 5% of systemic lupus erythematosus (SLE). Antibody levels were higher in patients with active or progressive SSc and correlated with the degree of skin fibrosis. Thus, immunity to MT-hsp65 appears in SSc and is not limited to RA. However, it does show some degree of specificity beyond chronic inflammation: PRP patients have a higher reactivity than do SLE patients.

Immunologically specific treatment of spontaneous insulin-dependent diabetes mellitus of NOD mice

This paper discusses the possibility of immunologically specific therapy of spontaneous autoimmune disease. The results of animal studies encourage optimism.

T cells in the spinal cord in experimental autoimmune encephalomyelitis are matrix adherent and secrete tumor necrosis factor alpha

We examined T cells isolated from an autoimmune tissue lesion and from lymphoid organs for their ability to secrete tumor necrosis factor-alpha (TNF-alpha) and to adhere to extracellular matrix (ECM) proteins. CD4+ T cells were obtained from spleens, popliteal lymph nodes, and spinal cords of Lewis rats that had been immunized with myelin basic protein (MBP) to induce experimental autoimmune encephalomyelitis (EAE). We now report that, irrespective of whether or not the T cells were activated with MBP or the T cell mitogen concanavalin A (ConA), the T cells isolated from the spinal cord lesions secreted greater amounts of TNF-alpha and adhered better to ECM than did T cells from the draining lymph node. Thus, the lesions of EAE concentrate a subpopulation of CD4+ T cells with enhanced ability to interact with blood vessel wall components and to secrete TNF-alpha.

Induction of experimental autoimmune encephalomyelitis by native myelin basic protein-activated T lymphocyte lines

Self antigens bind to MHC class II molecules in vivo. The capacity of class II molecules to bind native self antigen, namely antigen that has not been processed through an endososomal pathway, could increase susceptibility to autoimmune diseases if recognized by autoreactive T lymphocytes. To confirm this prediction we designed experiments to show that: (a) native myelin basic protein (BP) activates encephalitogenic T lymphocyte lines, and (b) these activated lines cause experimental autoimmune encephalomyelitis (EAE) in naive rats. We show that two encephalitogenic T lymphocytes lines, LEW and BN, are activated by native BP in the presence of paraformaldehyde pre-fixed antigen-presenting cells (APC). The degree of activation, as measured by T lymphocyte proliferation, was equal to that obtained in response to BP processed by APC prior to paraformaldehyde fixing. The response to native BP was confirmed by demonstrating insensitivity to the presence of the lysosomotropic agent chloroquine or protease inhibitors. Activation of T lymphocytes by BP required the presence of syngeneic APC. The activated T lymphocyte lines were injected into naive recipient rats that developed EAE within 5 days. Both disease incidence and severity were equal to that observed in rats that were treated with T lymphocytes activated by processed BP. Hence, at least in EAE, the risk of an autoimmune event could be precipitated by a complex of native antigen and class II molecules on cells that do not possess an endososomal pathway for antigen processing and presentation.

T lymphocyte adhesion to the fibronectin and laminin components of the extracellular matrix is regulated by the CD4 molecule

The adhesion of T cells to components of the extracellular matrix (ECM) is mediated by the beta 1 subfamily of integrin receptors, designated VLA. It has been recently demonstrated that the binding of VLA receptors to protein components of the ECM is rapidly augmented by the activation of the T cells without, however, any actual change in the level of expression of the VLA receptors for fibronectin (FN) or laminin (LN). Thus, it is likely that activation of existing VLA receptors is required for binding. The activation must be regulated by T cell surface molecules capable of transducing signals into the cell. We studied the role of the CD4 molecule in the binding of rat CD4+ T cells to the FN and LN components of the ECM. We now report that the CD4 molecule appears to play a major role in regulating T cell interactions with ECM. This conclusion is based on the following observations: (a) monoclonal antibodies directed against the CD4 molecule inhibited T cell adhesion to both FN and LN; (b) down-regulation of the CD4 molecule resulted in partial loss of the ability of CD4+ T cells to adhere to FN and LN; (c) a CD4+ T cell clone adhered to both FN and LN while a CD4-CD8- clone expressing an identical T cell receptor bound weakly to both proteins and (d) treatment of the CD4+ T cells with an inhibitor of the CD4-associated tyrosine protein kinase activity inhibited T cell adhesion to both ECM proteins.

Developmental toxicity of the dopamine agonist pergolide mesylate in CD-1 mice. II: Perinatal and postnatal exposure

Pergolide mesylate is a dopamine agonist and, therefore, reduces prolactin secretion. In Experiment I, pregnant mice were given oral doses of 0, 0.1, 0.3, 1.0 or 3.0 mg/kg/day pergolide on GD 15 through PD 10 or 20 to identify a tolerated dose which would not markedly reduce offspring survival during late gestational and lactational exposure. Offspring survival was not affected at any dose, but dose-related decreases in progeny body weights occurred at weaning. On PD 10, suckling-induced increases in maternal serum prolactin concentrations did not occur in dams treated with 3.0 mg/kg/day. In Experiment II, pregnant mice were given oral doses of 0, 0.002, 0.1 or 3.0 mg/kg/day pergolide on GD 15 through PD 20. Dams were allowed to deliver and maintain their offspring throughout a 21-day lactation period. Growth and behavioral performance of one F1 male and one F1 female per litter were monitored, followed by a reproduction trial and terminal organ weight measurements. There were no treatment-related effects on maternal body weights, food consumption, or terminal organ weights and pathology. Three dams showed overt signs of mammary inflammation and lactational insufficiency and mean progeny survival was decreased slightly in the 3.0 mg/kg/day group. There were no adverse effects on growth, development or reproductive performance in the F1 treatment-derived generation. Neonatal negative geotaxis, 1-h activity levels at 30 and 60 days of age, auditory startle habituation at 55 days of age, and two-way active avoidance performance at 65 days of age were not affected significantly by treatment. Thus doses of pergolide that did not inhibit lactation completely in the F0 dams were found to have no enduring effects on offspring development.

Vaccination against autoimmune mouse diabetes with a T-cell epitope of the human 65-kDa heat shock protein

Insulin-dependent diabetes mellitus is caused by autoimmune destruction of the insulin-producing beta cells resident in the pancreatic islets. We recently discovered that the pathogenesis of diabetes in NOD strain mice was associated with T-cell reactivity to an antigen cross-reactive with a mycobacterial 65-kDa heat shock protein. To identify peptide epitopes critical to the insulin-dependent diabetes mellitus of NOD mice, we studied the specificities of helper T-cell clones capable of causing hyperglycemia and diabetes. We now report the identification of a functionally important peptide within the sequence of the human variant of the 65-kDa heat shock protein molecule. T-cell clones recognizing this peptide mediate insulitis and hyperglycemia. Alternatively, the T cells can be attenuated and used as therapeutic T-cell vaccines to abort the diabetogenic process. Moreover, administration of the peptide itself to NOD mice can also down-regulate immunity to the 65-kDa heat shock protein and prevent the development of diabetes. Thus, T-cell vaccination and specific peptide therapy are feasible in spontaneous autoimmune diabetes.

Autoimmunity to chaperonins in the pathogenesis of arthritis and diabetes

The immunology of the 65 kd heat shock protein (hsp65) is paradoxical. Microbial and mammalian hsp65 molecules are 50% identical in amino acid sequence and immunologically cross-reactive, so microbial hsp65 looks like self; yet hsp65 is a dominant antigen in infection. Immunity to hsp65 can cause autoimmune diabetes in mice and may be related to autoimmune arthritis in rats and humans, so immunity to hsp65 should be forbidden; yet healthy persons manifest T-cell responses to self-hsp65. The aim of this chapter is to explore the immunological dominance of hsp65 and its role in autoimmunity--benign and pernicious.