A shared TCR CDR3 sequence in NOD mouse autoimmune diabetes

T cells involved in autoimmune diseases have been characterized by the genetic elements used to construct their autoimmune TCR. In the present study, we sequenced the alpha and beta chains of the TCR expressed by a CD4(+) T cell clone, C9, functional in NOD mouse diabetes. Clone C9 can adoptively transfer diabetes or, when attenuated, C9 can be used to vaccinate NOD mice against diabetes. Clone C9 recognizes a peptide epitope (p277) of the 60 kDa heat shock protein (hsp60) molecule. We now report that the C9 TCR beta chain features a CDR3 peptide sequence that is prevalent among NOD mice. This CDR3 element is detectable by 2 weeks of age in the thymus, and later in the spleen and in the autoimmune insulitis. Thus, a TCR CDR3beta sequence appears to be a common idiotope associated with mouse diabetes.

Regulation of NOD mouse autoimmune diabetes by T cells that recognize a TCR CDR3 peptide

NOD mice spontaneously develop type I diabetes resulting from autoimmune destruction of their insulin-producing beta cells. Among the self-antigens targeted by NOD autoimmune T cells is a peptide, p277, from the sequence of the 60 kDa heat shock protein (hsp60). Common to the anti-p277 T cell populations of NOD mice is an idiotope, C9, that spans the CDR3 region of the C9 TCR. We now report: (i) that the C9 idiotope peptide can be presented directly to anti-C9 anti-idiotypic T cells by C9 T cells, (ii) that spontaneous anti-C9 anti-idiotypic T cell activity falls as disease progresses, but immunization can activate the anti-idiotypic T cells to regulate the autoimmune process, (iii) that the anti-idiotypic T cells secrete IFN-gamma, but appear to control the disease by down-regulating the IFN-gamma produced by the pathogenic population of anti-p277 T cells, (iv) that intrathymic administration of the C9 idiotope peptide at 1 week of age can accelerate the disease, and (v) that administering the p277 target peptide can up-regulate the anti-idiotypic T cells and arrest the disease process. Thus, the development of NOD diabetes can be regulated by a balance between anti-idiotypic and anti-target peptide autoimmunity, and anti-idiotypic regulation can lead to changes in the cytokine secretion of the autoimmune T cells involved in the disease process.

The 60-kDa heat shock protein modulates allograft rejection

Allograft rejection is a process of immune reactivity triggered by foreign transplantation antigens. We now demonstrate that the 60-kDa heat shock protein (hsp60), a molecule that is identical in the donor and the recipient, can regulate allograft immunity. In wild-type mice, hsp60 expression was greatly enhanced in allografts being rejected. By using MHC class II (Ealpha) promoter hsp60 transgenic mice either as donors of skin with enhanced expression of hsp60, or as allograft recipients with decreased hsp60 autoimmunity, we found that augmented expression of mouse hsp60 in the allograft accelerated its rejection, whereas reduced autoimmunity to mouse hsp60 in graft recipients delayed the process. Moreover, in nontransgenic mice, therapeutic administration of hsp60 or hsp60 peptides, known to modulate naturally occurring hsp60 autoimmunity, led to delayed allograft rejection. Thus, we demonstrate that hsp60 expression and hsp60 autoimmunity can influence and modify the immune response to foreign antigens. Hence, autoimmunity to self-hsp60 epitopes is not necessarily an aberration, but may serve physiologically and therapeutically to modulate foreign immunity.

T cell proliferative responses of type 1 diabetes patients and healthy individuals to human hsp60 and its peptides

T cell responses to peptide epitopes of the 60 kDa heat shock protein (hsp60) have been shown to play a role in the pathogenesis of type 1 insulin-dependent diabetes mellitus (IDDM) in mice. To test whether hsp60 autoimmunity might be involved in human type 1 diabetes, we studied T cell proliferative responses (stimulation index; SI) to intact human hsp60, to hsp60 peptides and to a recall antigen (tetanus toxoid) in 25 newly diagnosed type 1 diabetes patients, in 22 type 2 (non-insulin-dependent diabetes mellitus, NIDDM) patients, and in 25 healthy blood donors. There were no significant differences between the T cell responses of the three groups to tetanus toxoid. However, the responses to hsp60 of the type 1 diabetes group (median SI=5) were significantly greater (P<0. 01) than those of the type 2 group (median SI=1.67) and of the blood donors (median SI=1.7). Epitope mapping revealed significant responses to at least seven different peptides, with prevalent responses to the p277 peptide previously mapped in NOD mice and to peptide p32. Thus, newly diagnosed type 1 diabetes patients, similar to prediabetic and newly diabetic NOD mice, show heightened autoimmunity to hsp60 and hsp60 peptides.

A cellulose-binding domain-fused recombinant human T cell connective tissue-activating peptide-III manifests heparanase activity

The chemokine connective tissue-activating peptide (CTAP)-III, which belongs to the leukocyte-derived growth factor family of mediators, was previously shown to be mitogenic for fibroblasts. However, it has recently been shown that CTAP-III, released from platelets, can act like a heparanase enzyme and degrade heparan sulfate. This suggests that CTAP-III may also function as a proinflammatory mediator. We have successfully cloned CTAP-III from a lambdagt11 cDNA library of PHA-activated human CD4(+) T cells and produced recombinant CTAP-III as a fusion protein with a cellulose-binding domain moiety. This recombinant CTAP-III exhibited heparanase activity and released degradation products from metabolically labeled, naturally produced extracellular matrix. We have also developed polyclonal and monoclonal antibodies, and these antibodies against the recombinant CTAP-III detected the CTAP-III molecule in human T cells, polymorphonuclear leukocytes, and placental extracts. Thus, our study provides tools to examine further immune cell behavior in inflamed sites rich with extracellular moieties and proinflammatory mediators.

Self heat-shock protein (hsp60) peptide serves in a conjugate vaccine against a lethal pneumococcal infection

Healthy persons manifest a high frequency of T cells reactive to epitopes of the self 60-kDa heat-shock protein (hsp60) molecule. It was reasoned that a self hsp60 peptide, p458m, might provide T cell help for a response to the T independent capsular polysaccharide of Streptococcus pneumoniae type 4 (PS4). The conjugate vaccine (PS4-p458m) induced resistance to challenge with >300,000 times the minimal lethal dose of pneumococci. PS4 conjugated to other immunogenic carriers (tetanus toxoid, a pneumolysin peptide, and others) or a commercial pneumococcal vaccine were far less effective. The effectiveness of the PS4-p458m conjugate was associated with an increased IgG1 antibody response to PS4, with long-term memory, and with T cell responses to the p458m peptide. Thus, T cell reactivity to a self epitope in a conjugate vaccine can be mobilized to induce help for resistance to a lethal infection.

The pathogenicity of islet-infiltrating lymphocytes in the non-obese diabetic (NOD) mouse

The aim of the present study was to investigate the pathogenic properties of islet-infiltrating lymphocytes related to the severity of the autoimmune destruction of islet beta-cells in the NOD mouse. We analysed the development of insulin-dependent diabetes mellitus (IDDM) produced by adoptive transfer of islet lymphocytes from NOD into NOD.scid mice. Here we show that the transfer was most effective when both CD4+ and CD8+ T cells were present in the infiltrate, but CD4+ T cells alone were sufficient to cause the disease. Islet lymphocytes from both females and males transferred diabetes effectively, but the severity of IDDM was higher when female islet lymphocytes were used. Unexpectedly, the sensitivity of male islets to beta-cell damage was greater than that of female islets. Treatment of NOD females with a peptide of heat shock protein (hsp)60, p277, known to protect NOD mice from IDDM, reduced the pathogenicity of the islet lymphocytes. In contrast, administration of cyclophosphamide to males, a treatment that accelerates the disease, rendered the islet lymphocytes more pathogenic. More severe disease in the recipient NOD.scid mice was associated with more interferon-gamma (IFN-gamma)-secreting islet T cells of the NOD donor. The disease induced by islet lymphocytes was strongly inhibited by co-transfer of spleen cells from prediabetic mice, emphasizing the regulatory role of peripheral lymphocytes. Thus, the cellular characteristics of the islet infiltrate and the pathogenicity of the cells are subject to complex regulation.

Diversity of the B cell repertoire to myelin basic protein in rat strains susceptible and resistant to EAE

Myelin basic protein (MBP) is a major protein of central nervous system myelin which can induce experimental autoimmune encephalomyelitis (EAE) in susceptible laboratory animals. The role of T cells in the induction of EAE has been extensively studied, but the antibody response to MBP has not been well characterized. In the present work, we immunized rats with encephalitogenic guinea-pig MBP and mapped autoreactive antibodies binding to peptides in the rat MBP sequence. We studied the responses of the Lewis rat strain, susceptible to EAE, and the responses of the Fischer and Brown-Norway (BN) rats, resistant to EAE. We found that Lewis rats immunized to guinea-pig MBP develop antibodies to a diversity of MBP epitopes with a dominance of MBP peptide p11-30 and peptides in the 71-140 region. Fischer rats showed a similar pattern of antibody specificities, but with higher titers than the Lewis rats. BN rats, in contrast, developed a very low titer of antibodies and lacked a response to p11-30. Thus, there is no clear correlation between the nature of the anti-MBP antibody response and the state of susceptibility or resistance to EAE induction in the different rat strains.

Autoimmune T cells protect neurons from secondary degeneration after central nervous system axotomy

Autoimmunity to antigens of the central nervous system is usually considered detrimental. T cells specific to a central nervous system self antigen, such as myelin basic protein, can indeed induce experimental autoimmune encephalomyelitis, but such T cells may nevertheless appear in the blood of healthy individuals. We show here that autoimmune T cells specific to myelin basic protein can protect injured central nervous system neurons from secondary degeneration. After a partial crush injury of the optic nerve, rats injected with activated anti-myelin basic protein T cells retained approximately 300% more retinal ganglion cells with functionally intact axons than did rats injected with activated T cells specific for other antigens. Electrophysiological analysis confirmed this finding and suggested that the neuroprotection could result from a transient reduction in energy requirements owing to a transient reduction in nerve activity. These findings indicate that T-cell autoimmunity in the central nervous system, under certain circumstances, can exert a beneficial effect by protecting injured neurons from the spread of damage.

Immunity to p53 induced by an idiotypic network of anti-p53 antibodies: generation of sequence-specific anti-DNA antibodies and protection from tumor metastasis

The general overexpression of p53 by different types of tumor cells suggests that p53 immunity might be generally useful for tumor immunotherapy. We describe here the induction of immunity to p53 and resistance to tumor metastasis using an idiotypic network. Mice were immunized with domain-specific anti-p53 monoclonal antibodies (Ab1): PAb-248 directed to the N-terminus; PAb-246 directed to the specific DNA-binding region; or PAb-240 directed to a mutant p53 that does not bind specific DNA. Immunized mice responded by making anti-idiotypic antibodies (Ab2) specific for the Ab1 inducer. Ab1 PAb-246 induced Ab2 that, like p53 itself, could bind the specific DNA oligonucleotide sequence of the p53 responsive element. Mice immunized with Ab1 PAb-240 or PAb-246 spontaneously made Ab3 anti-p53 antibodies that reflected the specificity of their Ab1 inducers: Ab1 PAb-246 induced Ab3 specific for wild-type p53; PAb-240 induced Ab3 specific for mutant p53. Ab1 PAb-248 induced only Ab2. The spontaneously arising Ab3 were of T cell-dependent IgG isotypes. Peptides from the complementarity determining regions of the Ab1 antibodies PAb-240 and PAb-246 could also induce Ab3 anti-p53. Finally, mice that produced Ab3 anti-p53 acquired resistance to tumor metastases. Therefore, an anti-idiotypic network built around certain domains of p53 seems to be programmed within the immune system, specific Ab2 antibodies can mimic the DNA binding domain of p53, and Ab3 network immunity to p53 can be associated with resistance to tumor cells.

Production and purification of a recombinant human hsp60 epitope using the cellulose-binding domain in Escherichia coli

The heat shock protein hsp60 plays a functional role in insulin-dependent diabetes mellitus. The hsp60 epitope p277 (aa 437-aa 460) is effective in vaccinating mice against diabetes. A synthetic peptide gene (p277) that encodes the human hsp60 epitope was cloned to the 3' end of the cellulose-binding domain gene (cbd). CBD-p277 was overexpressed in Escherichia coli and purified on a cellulose column. A methionine at the C-terminal end of CBD enabled CNBr cleavage between CBD and p277. After CNBr cleavage, free CBD and residual uncleaved CBD-p277 were recovered by cellulose chromatography. The p277 peptide was further purified on a RPC-FPLC column. The molecular weight of the recombinant peptide was confirmed by electrospray mass spectrometry. The recombinant peptide was found to be biologically active in assays involving clone C9 T-cell proliferation, lymph-node cell proliferation, and antibody production. Thus the use of CBD as an affinity tag and the utilization of affordable cellulose matrices offers an attractive method for the production and purification of recombinant peptides.

Accumulation of passively transferred primed T cells independently of their antigen specificity following central nervous system trauma

The central nervous system (CNS) enjoys a unique relationship with the immune system. Under non-pathological conditions, T cells move through the CNS but do not accumulate there. CNS trauma has been shown to trigger a response to CNS self-antigens such as myelin basic protein (MBP). Here, we examined whether the injured CNS tissue undergoes changes that permit T cell accumulation. We found that injury to CNS white matter, such as the optic nerve, led to a transiently increased accumulation of T cells (between days 3 and 21). In Lewis rats with unilaterally injured optic nerves, systemic administration of passively transferred T cells recognizing either self-antigen (MBP) or non-self-antigen (ovalbumin) resulted in accumulation of the T cells in injured optic nerve, irrespective of their antigenic specificity. The effect of the T cells on the damaged nerve, the lack of selectivity in T cell accumulation and the mechanism underlying non-selective accumulation are discussed.

Idiotypic immunization induces immunity to mutated p53 and tumor rejection

The p53 molecule might serve as a common tumor-associated antigen, as the tumor suppressor gene p53 is mutated and the p53 protein is often over-expressed in tumor cells. We report that effective immunity to p53 can be induced through an idiotypic network by immunization of mice with a monoclonal antibody (PAb-240) specific for mutated p53, or with a peptide derived from the complementarity determining region (CDR) 3 of the variable domain of the light chain (VL) of this antibody. The immunized mice produced IgG antibodies to p53 and mounted a cytotoxic reaction to a tumor line bearing mutated p53. The idiotypically immunized mice were resistant to challenge with the tumor cells. Thus antibodies to p53 might serve as immunogens for activating resistance to some tumors. At the basic level, these findings indicate that a network of p53 immunity may be organized naturally within the immune system.

Immune information, self-organization and meaning

To effect the molecular integrity of the individual, the immune system has to gather antigenic information and respond in a meaningful way. Immunologists traditionally have focused their research on analyzing the component parts of the system. The achievements of immunology in its analytical enterprise have now made it possible to begin the task of synthesis. In this paper, we shall consider how the immune system combines germline and somatic information using a chemical language to establish the functional meaning of antigens.

The selective estrogen receptor modulator, raloxifene: a segment II/III delivery study in rats

Raloxifene is a nonsteroidal, selective estrogen receptor modulator developed by Eli Lilly and Company as a therapeutic agent for postmenopausal osteoporosis. Raloxifene was administered orally by gavage at doses of 0, 0.1, 1, or 10 mg/kg/d to female CD rats (25/group) on Gestation Day 6 (GD 6) through Postpartum Day 20 (PD 20). Females were allowed to deliver and maintain their progeny until PD 21. All dead pups and pups culled on PD 1 were given internal and external examinations. One pup/sex/litter was assigned to each of the following assessment groups: 1) the primary pair for the F1 generation study, in which survival, growth, development, behavior, indicators of sexual maturation, and reproductive performance were evaluated; 2) terminal necropsy evaluations at PD 21; 3) terminal necropsy evaluations at 60 d of age; and 4) assessments of immune function at 5 to 6 weeks of age. At termination on PD 21, 60, or approximately 140, a necropsy was performed; crown rump and tibia lengths were measured; pituitary weights were taken; and a portion of the anterior pituitary was retained for growth hormone, luteinizing hormone, and prolactin content determinations (control and 10-mg/kg groups only). The remainder of the pituitary and reproductive tissues were retained for histologic evaluations. Dose-related depressions in maternal body weight and food consumption occurred during gestation. Mean gestation length was increased at 1 and 10 mg/kg. Delayed, extended, and/or disrupted parturition occurred in dams given 10 mg/kg, which resulted in a high incidence of maternal morbidity and/or death, increased numbers of dead pups, and the survival of only 66% of live pups to PD 21. Progeny body weights were not decreased at birth, but were depressed progressively in a dose-related manner during the 3-week lactation period. Negative geotaxis and incisor eruption were apparently accelerated in the 1- and 10-mg/kg groups, but eye opening was delayed at 10 mg/kg. Postweaning activity levels, auditory startle, and passive avoidance performance were not affected in the raloxifene groups. Dose-related decreases in spleen cellularity and thymus weights occurred in both sexes, but immune system function, as measured by splenic natural killer cell activity and antibody response to sheep red blood cells, was not affected. Postweaning body weights and growth parameters, as well as pituitary hormone content, were affected in both an age- and sex-specific manner. Preputial separation was not affected, but vaginal patency occurred ca 2 d earlier than controls in females from the 10-mg/kg group. Estrous cycles of the F1 females were not affected during the first two weeks after vaginal opening, but were disrupted at 12 to 14 weeks of age in the 10-mg/kg group. These females showed poorer mating and fertility indices, and litter size was reduced in the two females that were pregnant. Histologically, reproductive organs were not affected in males at any age or in females at PD 21. At PD 60, vaginal mucification occurred in females from the 0.1- and 1-mg/kg groups. At PD 140, the only finding was a high rate of uterine hypoplasia in the 10-mg/kg group, and this finding occurred in the absence of any concomitant ovarian or vaginal changes. These reproductive and developmental findings are consistent with estrogen antagonist activity of raloxifene.

Low-dose low-molecular-weight heparin (enoxaparin) is beneficial in lichen planus: a preliminary report

BACKGROUND

Low-dose heparin devoid of anticoagulant activity inhibits T-lymphocyte heparanase activity, which is crucial in T-cell migration to target tissues.

OBJECTIVE

The purpose of this study was to assess the efficacy of low-dose enoxaparin (Clexane), a low-molecular-weight heparin, as monotherapy in lichen planus.

METHODS

Included in the study were 10 patients with widespread histopathologically proven lichen planus (LP) associated with intense pruritus of several months' duration. Patients were given 3 mg enoxaparin, subcutaneously once weekly; three patients received four injections, and seven patients received six injections.

RESULTS

In nine patients the itch disappeared within 2 weeks. Within 4 to 10 weeks in eight of these patients, there was complete regression of the eruption with residual postinflammatory hyperpigmentation; in one patient, there was marked improvement. In one patient, no effect was observed. Of the four patients who also had oral LP, only one showed improvement. No side effects were observed in any of the patients.

CONCLUSION

These findings indicate that enoxaparin may be a simple, effective treatment for cutaneous LP.

Islet T cells secreting IFN-gamma in NOD mouse diabetes: arrest by p277 peptide treatment

Non-obese diabetic (NOD) mice spontaneously develop insulin-dependent (type 1) diabetes mellitus (IDDM) caused by T cells which destroy the insulin-producing islet beta-cells. Since cytokines are involved in this auto-immune beta-cell damage, we used an ELISPOT assay to enumerate the islet-associated T cells that secreted interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) or interleukin-4 (IL-4). We used mitogenic anti-CD3 antibody to activate all the T cells capable of responding, irrespective of their antigen specificity. We found that NOD females, more susceptible than males to IDDM, accumulated islet IFN-gamma producers more rapidly with age than did the males. Acceleration of male IDDM by cyclophosphamide led to a marked increase in IFN-gamma secreting islet T cells. In contrast, a decrease in IFN-gamma-producing islet T cells was associated with arrest of IDDM by administration of peptide p277 of the 60 kDa heat-shock protein (hsp60) to 12-week-old female NOD mice. The p277-treated mice later manifested a greater number of islets and fewer leukocytes per islet than did the mice treated with a bacterial hsp60 peptide. Thus, the development of diabetes could be correlated with the accumulation in the islets of T cells producing IFN-gamma, and destructive insulitis could be downregulated by the administration of a single peptide.

Biochemical characterization of the human diabetes-associated HLA-DQ8 allelic product: similarity to the major histocompatibility complex class II I-A(g)7 protein of non-obese diabetic mice

The human HLA-DQ8 (A1*0301/B1*0302) allelic product manifests a strong association with insulin-dependent diabetes mellitus (IDDM). Previous biochemical studies of the major histocompatibility complex (MHC) class II I-A(g)7 protein of IDDM-prone non-obese diabetic mice produced controversial results. To better define the biochemical properties of IDDM-associated MHC class II molecules, we analyzed DQ8 proteins, in comparison to other DQ allelic products, by partially denaturing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). We now report that DQ8 proteins have a normal peptide occupancy and lifespan in cells. Similar to I-A(g)7, DQ8 proteins formed only a minor fraction of SDS-stable complexes with peptides. Although this phenotype was not unique to DQ8, some DQ allelic products such as IDDM-protective DQ6 proteins were SDS resistant. The DQ9 allelic product, differing from DQ8 only at position (P) beta 57, was SDS stable, suggesting that non-Asp residues at beta 57 might decrease the SDS stability of DQ proteins. We identified a single peptide which specifically induced an SDS-stable conformation in DQ8 as well as in I-A(g)7 molecules. The residues at anchor P1 in this peptide were found to influence the SDS stability of both molecules. Together with our previous observation of similar binding motifs of I-A(g)7 and DQ8, these results demonstrate an overall biochemical similarity of mouse and human diabetes-associated MHC class II molecules. This similarity might contribute to a common immunological mechanism of IDDM in both species.

Heparin disaccharides inhibit tumor necrosis factor-alpha production by macrophages and arrest immune inflammation in rodents

Inflammation is the clinical expression of chemical mediators such as the pro-inflammatory cytokine tumor necrosis factor (TNF-)-alpha produced by macrophages and other cells activated in the immune response. Hence, agents that can inhibit TNF-alpha may be useful in treating arthritis and other diseases resulting from uncontrolled inflammation. We now report that the cleavage of heparin by the enzyme heparinase I generates sulfated disaccharide (DS) molecules that can inhibit the production of TNF-alpha. Administration of nanogram amounts of the sulfated DS molecules to experimental animals inhibited delayed-type hypersensitivity to a skin sensitizer and arrested the joint swelling of immunologically induced adjuvant arthritis. Notably, the sulfated DS molecules showed a bell-shaped dose-response curve in vitro and in vivo: decreased effects were seen using amounts of the DS molecules higher than optimal. Thus, molecular regulators of inflammation can be released from the natural molecule heparin by the action of an enzyme.

Treatment of NOD diabetes with a novel peptide of the hsp60 molecule induces Th2-type antibodies

A peptide from the sequence of hsp60 molecule, designated p277, has been shown to be functionally involved in modulating the development of auto-immune diabetes in the NOD mouse: administration of p277 to NOD mice can arrest the diabetogenic autoimmune process, even when far advanced. Is p277 the only hsp60 peptide able to modulate the disease? We mapped T cell responses to peptides spanning the mouse hsp60 molecule and identified an immunogenic peptide, designated p12, that is also functional in arresting NOD diabetes. Although no spontaneous T cell reactivity to p12 could be detected in NOD mice, subcutaneous administration of 100 microg of p12 in mineral oil to 10-week-old female NOD mice, similar to treatment with p277, significantly prevented progression of the disease. Administration of other immunogenic peptides was not effective. A peptide from the glutamic acid decarboxylase (GAD65) sequence, GADp35, and a peptide from the myco-bacterial hsp60 molecule did not influence the development of diabetes. The effectiveness of hsp60 peptides p12 and p277 was associated with the induction of antibodies to the peptides of the IgG1 and IgG2b isotypes, antibodies which appear to be regulated by anti-inflammatory cytokines. There was a negative correlation between the amounts of antibodies induced by the hsp60 peptides and the level of blood glucose. Thus, more than one peptide of the hsp60 molecule can be used to inhibit the development of NOD diabetes, and the effect of peptide therapy appears to be associated with the induction of specific antibody isotypes.

The Th1/Th2 dichotomy, hsp60 autoimmunity, and type I diabetes

This paper presents some questions and issues regarding the concept of the Th1/Th2 dichotomy and summarizes results using an hsp60 peptide to treat the spontaneous autoimmune process of diabetes in NOD mice.

Exploring the potential of DNA vaccination

DNA vaccines offer a unique means of stimulating and enhancing the immune response. Subjects are vaccinated with the gene for a particular antigen rather than with the antigen itself--the foreign protein that elicits the response is made intracellularly. This new type of gene therapy may not only extend the limits of immunoprotection but may also provide new insight into microbiologic and immunologic processes.

Hsp60 peptide therapy of NOD mouse diabetes induces a Th2 cytokine burst and downregulates autoimmunity to various beta-cell antigens

A peptide of the human 60-kDa heat-shock protein (hsp60), designated p277, was found to be useful as a therapeutic agent to arrest the autoimmune process responsible for diabetes in nonobese diabetic (NOD) mice. The effectiveness of peptide treatment was associated with the induction of peptide-specific antibodies of the IgG1 but not of the IgG2a isotype, suggesting the possibility that a Th2-type response may have been induced. We now report that the effectiveness of p277 treatment is associated with the transient activation of anti-p277 splenic T-cells that produce the Th2 cytokines interleukin-4 (IL-4) and IL-10. The Th2 response to p277 was associated with reduced Th1-type autoimmunity to hsp60 and to two other target antigens associated with diabetes: GAD and insulin. The Th2 shift appeared to be relatively specific; spontaneous T-cell reactivity to a bacterial antigen peptide remained in the Th1 mode in the p277-treated mice. Moreover, treatment with the bacterial peptide did not induce a change in cytokine profile, and it did not affect progression of the disease. Thus, effective peptide treatment of the diabetogenic process associated with the induction of antibodies may be explained by selective and transient activation of Th2 autoimmune reactivity.

Molecular characterization of the diabetes-associated mouse MHC class II protein, I-Ag7

The MHC class II molecule of the non-obese diabetic (NOD) mice, I-Ag7, is associated with susceptibility to autoimmune diabetes. To try to understand the molecular basis of this association, we analyzed the peptide binding properties and intracellular behavior of I-Ag7 in comparison with other I-A haplotypes. We found that I-Ag7 molecules manifested normal intracellular trafficking and lifespan, and a small but clearly detectable fraction of I-Ag7 in the cells formed SDS-resistant compact dimers. The binding of an antigenic reference peptide to I-Ag7 was stable and was accompanied by compact dimer formation. Our analysis of the binding specificity of I-Ag7 revealed a peptide binding motif of nine amino acids with a degenerate position at P1 and three conserved anchor positions: P4, P6 and P9. An allele-specific preference for negatively charged residues was found at P9, apparently due to the presence of the rare Ser residue at position 57 of the I-Ag7 beta chain. These findings could have implications for the mechanisms of MHC-mediated susceptibility to autoimmune diabetes in the NOD mice.

IL-2 and TNF receptors as targets of regulatory T-T interactions: isolation and characterization of cytokine receptor-reactive T cell lines in the Lewis rat

T cells are considered to be of prime importance in immune regulation of both B and T cell functions. The targets of recognition in T-T cell interactions are not clear. Most recent experimental work has focused on the idiotypic regulatory interactions mediated by TCR peptides. There is experimental evidence that regulatory cells exist that do not recognize the TCR. This type of regulation is selectively induced by activated T cells. Therefore, we designed this study to examine the possible role of cytokine receptors as targets of immune regulation. We tested two peptides of IL-2R alpha-chain, 2 of IL-2R beta-chain, and one of TNFR (p60). All peptides were found to be immunogenic at inducing T cell proliferation and four induced Abs in Lewis rats. We generated T cell lines to these five peptides, and tested them both in vitro and in vivo. We found that the T cells exhibited a proliferative response when cultured with activated, irradiated stimulator cells that were augmented upon addition of the cytokine receptor peptide. The cytokine profile of the lines was characterized as well as the Vbeta gene composition. One of the lines significantly protected against active encephalomyelitis. These results point at cytokine receptors as possible targets of immune regulation and T-T cell interactions.

IL-2 and TNF receptors as targets of regulatory T-T interactions: isolation and characterization of cytokine receptor-reactive T cell lines in the Lewis rat

T cells are considered to be of prime importance in immune regulation of both B and T cell functions. The targets of recognition in T-T cell interactions are not clear. Most recent experimental work has focused on the idiotypic regulatory interactions mediated by TCR peptides. There is experimental evidence that regulatory cells exist that do not recognize the TCR. This type of regulation is selectively induced by activated T cells. Therefore, we designed this study to examine the possible role of cytokine receptors as targets of immune regulation. We tested two peptides of IL-2R alpha-chain, 2 of IL-2R beta-chain, and one of TNFR (p60). All peptides were found to be immunogenic at inducing T cell proliferation and four induced Abs in Lewis rats. We generated T cell lines to these five peptides, and tested them both in vitro and in vivo. We found that the T cells exhibited a proliferative response when cultured with activated, irradiated stimulator cells that were augmented upon addition of the cytokine receptor peptide. The cytokine profile of the lines was characterized as well as the Vbeta gene composition. One of the lines significantly protected against active encephalomyelitis. These results point at cytokine receptors as possible targets of immune regulation and T-T cell interactions.

The peptide binding specificity of the MHC class II I-A molecule of the Lewis rat, RT1.BI

The specificity of peptide binding to MHC molecules is defined by binding motifs composed of several relatively conserved anchor positions. The peptide binding motifs of murine MHC class II I-A molecules are functionally important but poorly characterized. Here we use peptide binding studies and isolation of naturally presented peptides to characterize the peptide binding motif of the MHC class II I-A molecule, RT1.BI, a molecule that is involved in experimental autoimmunity in the Lewis rat. We now report that, similar to other class II motifs, the RT1.BI motif consists of a nonamer sequence with four major anchor positions (P1, P4, P6 and P9). Residues at P4 and P9, rather than at P1, appeared to be particularly important for binding. Negatively charged residues were favored at P9, consistent with the presence of a serine at position 57 of the RT1.BI beta chain. This RT1.BI motif could be observed in the dominant autoantigenic T cell epitopes mapped previously in the Lewis rat. These results highlight a general similarity and some important differences in the organization of MHC class II peptide binding motifs. The reported RT1.BI motif should facilitate the prediction and design of T cell epitopes for the induction and control of experimental autoimmune diseases in Lewis rat models.

An alpha-chain TCR CDR3 peptide can enhance EAE induced by myelin basic protein or proteolipid protein

Regulation of experimental autoimmune encephalomyelitis (EAE) can be induced by anti-idiotype immunity against T cell receptor (TCR) fragments associated with major histocompatibility complex (MHC) molecules. However, we have recently found that preimmunization with an alpha-chain TCR CDR3 peptide (LYFCAARSNYQL) derived from myelin basic protein (MBP)-specific clones did not suppress but rather augmented the severity of EAE induced by MBP-specific T cells in SJL/J mice. To test whether CDR3 vaccination could control only a highly restricted T cell population, we studied the effect of the peptide against EAE induced by T cells specific for different Ag/MHC ligands and autoimmune diseases affecting non-neural tissues. In contrast to expectations, the peptide was found to augment not only EAE induced by MBP-specific T cells, but also proteolipid protein (PLP)-specific T cell- or PLP peptide-induced EAE in SJL/J mice, and MBP-induced EAE and adjuvant arthritis (AA) in rats. The CDR3 peptide was neither inhibitory nor supportive for Ag-induced activation of an encephalitogenic clone in vitro. In addition, the peptide treatment neither inhibited the induction of Ag-specific T cells nor altered the APC function of spleen cells. These findings, on the one hand, confirm previous results showing TCR peptide-induced enhancement of the disease and, on the other hand, indicate that the TCR CDR3 peptide may control T cells with broader Ag/MHC specificities than could be expected. Structural similarity among TCR idiotypes of autoimmune T cells may partly account for these results.

The hsp60 peptide p277 arrests the autoimmune diabetes induced by the toxin streptozotocin

The development of autoimmune diabetes in the NOD strain of mice (H-2g7) is marked by the presence of T-cells reactive to the p277 peptide of the 6O-kDa heat shock protein (hsp60). We have found that the p277 peptide can be used as a therapeutic vaccine to arrest NOD diabetes. Recently, we found that T-cell autoimmunity to p277 also develops spontaneously in C57BL/KsJ mice (H-2d) during the induction of autoimmune diabetes by a very low dose of the beta-cell toxin streptozotocin (STZ). We now report the inhibition of STZ toxin-induced autoimmune diabetes by p277 peptide therapy. Administration of two doses each of 100 micrograms of peptide p277 in mineral oil given 1 week after toxin induction and 85 days later was most effective. The effect of p277 on STZ toxin-induced diabetes was marked by a shift in p277 autoimmunity from a T-cell proliferative response to the production of anti-p277 antibodies. The anti-p277 antibodies were predominantly of the IgG1 and IgG2b isotypes, known to be regulated by Th2 type cytokines; IgG2a antibody, known to be dependent on interferon (IFN)-gamma, was induced to a much lesser degree. Peptide p277 therapy was specific: treatment of the mice with an immunogenic peptide from the sequence of another antigen, GADp34, failed to prevent the development of diabetes. The GADp34 peptide induced lower titers of specific antibodies, and the antibodies were predominantly of the IgG2a class. Thus, p277 peptide therapy, marked by the induction of Th2-type antibodies, can be effective in toxin-induced autoimmune diabetes.

Suppressive vaccination with DNA encoding a variable region gene of the T-cell receptor prevents autoimmune encephalomyelitis and activates Th2 immunity

A variable region gene of the T-cell receptor, V beta 8.2, is rearranged, and its product is expressed on pathogenic T cells that induce experimental autoimmune encephalomyelitis (EAE) in H-2u mice after immunization with myelin basic protein (MBP). Vaccination of these mice with naked DNA encoding V beta 8.2 protected mice from EAE. Analysis of T cells reacting to the pathogenic portion of the MBP molecule indicated that in the vaccinated mice there was a reduction in the Th1 cytokines interleukin-2 (IL-2) and interferon-gama. In parallel, there was an elevation in the production of IL-4, a Th2 cytokine associated with suppression of disease. A novel feature of DNA immunization for autoimmune disease, reversal of the autoimmune response from Th1 to Th2, may make this approach attractive for treatment of Th1-mediated diseases like multiple sclerosis, juvenile diabetes and rheumatoid arthritis.

Lymph node cell vaccination against the lupus syndrome of MRL/lpr/lpr mice

Immunization with pathogenic lymphoid cells has been shown to induce resistance to disease in experimental animal models of cell mediated autoimmunity. In the present work we tested the effectiveness of this approach in a spontaneous murine autoimmune disease, the MRL/lpr/lpr (MRL/1) murine lupus model. We now report that the anti-DNA antibodies and glomerulonephritis of MRL/1 mice could be prevented by the adoptive transfer of spleen cells from MRL/+ mice that had been vaccinated with MRL/1 lymph node T lymphocytes, but not by direct vaccination of MRL/1 mice with their cells. These results indicate that the lupus of MRL/1 mice is susceptible to regulation by adoptive vaccination and that these autoimmune mice lack the ability to raise a suppressive response against their own pathogenic cells.

NOD mouse diabetes: the ubiquitous mouse hsp60 is a beta-cell target antigen of autoimmune T cells

In the NOD mouse, the onset of beta-cell destruction is associated with spontaneous development of T-lymphocytes reactive to members of the 60 kDa heat shock protein (hsp60) family, including the Mycobacterial (MT) and the human (H) hsp60 molecules. Diabetes in the NOD mouse is a spontaneous tissue-specific autoimmune disease occurring without prior immunization. Therefore, it has been suggested that the anti-hsp60 T cells involved in the autoimmune diabetes of NOD mice might reflect molecular mimicry between MT-hsp60 and a beta-cell tissue specific molecule sharing similar T cell epitopes, the p277 peptide of hsp60 in particular. We cloned and expressed the mouse hsp60 cDNA from a beta-cell tumour. This mouse beta-cell hsp60 cDNA was found to be identical in sequence to the hsp60 of mouse fibroblasts. We further report that NOD spleen cells and an NOD diabetogenic T cell clone C9 responded to the recombinant mouse hsp60 and to its peptide M-p277 to the same extent as to H-hsp60 and H-p277. Splenocytes of mice of other strains did not respond to p277. Moreover, treatment of 3 month old NOD mice with the non-modified self M-p277 peptide was as efficient as H-p277, from which it differs in one amino acid, in halting progression of the disease. Thus, anti-H-p277 T cells modulating diabetes in the NOD mouse are autoreactive, and are targeted at the mouse beta-cell hsp60, which is not tissue specific. These findings raise the question of how a non-tissue specific molecule may be a target of a tissue-specific autoimmune disease.

A role of Hsp60 in autoimmune diabetes: analysis in a transgenic model

A pathogenic role for self-reactive cells against the stress protein Hsp60 has been proposed as one of the events leading to autoimmune destruction of pancreatic beta cells in the diabetes of nonobese diabetic (NOD) mice. To examine this hypothesis, we generated transgenic NOD mice carrying a murine Hsp60 transgene driven by the H-2E alpha class II promoter. This would be expected to direct expression of the transgene to antigen-presenting cells including those in the thymus and so induce immunological tolerance by deletion. Detailed analysis of Hsp60 expression revealed that the endogenous gene is itself expressed strongly in thymic medullary epithelium (and weakly in cortex) yet fails to induce tolerance. Transgenic mice with retargeted Hsp60 showed overexpression of the gene in thymic cortical epithelium and in bone marrow-derived cells. Analysis of spontaneous T-cell responses to a panel of self and heterologous Hsp60 antigens showed that tolerance to the protein had not been induced, although responses to an immunodominant 437-460 epitope implicated in disease were suppressed, probably indicating an epitope shift. This correlated with changes in disease susceptibility: insulitis in transgenic mice was substantially reduced so that pathology rarely progressed beyond periislet infiltration. This was reflected in a substantial reduction in hyperglycemia and disease. These data indicate that T cells specific for some epitopes of murine Hsp60 are likely to be involved in the islet-cell destruction that occurs in NOD mice.

IL-2 rescues antigen-specific T cells from radiation or dexamethasone-induced apoptosis. Correlation with induction of Bcl-2

Most studies of apoptosis on T lymphocytes have examined the effects of various stimuli on immature T cells from the thymus. Previous work has indicated that apoptosis of mature memory T cells may be an important pathophysiologic mechanism in diseases such as AIDS, cancer, and autoimmunity. The effect of IL-2 on apoptosis of T cells is not clear. Therefore, we studied the ability of IL-2 to rescue Ag-specific T cells from apoptosis. We found that IL-2, in a dose-dependent manner, prevented T cells from entering apoptosis induced by gamma-irradiation, mitomycin C, or dexamethasone. This effect was specific for IL-2; IL-1 beta, IL-6, or IFN-gamma could not reproduce it. In contrast to Ag-specific T cells, immature T cells and naive mature peripheral T cells could not be rescued by IL-2 from radiation-induced apoptosis. Apoptosis rescue by IL-2 was associated with the induction of bcl-2 mRNA and protein. This induction could not be attributed to the effects of IL-2 on the cell cycle, as T cells that were prevented from cell cycle progression by irradiation showed a similar induction of bcl-2. Rescued cells retained their Ag-specific proliferative capacity and in vivo functions. These findings demonstrate that the apoptotic death of Ag-specific T cell lines, cells which can be regarded as a model for memory T cells, can be prevented with IL-2. This effect may have important therapeutic implications for patients receiving chemotherapy or radiotherapy, and for patients with AIDS who develop immunodeficiency primarily as a result of loss of Ag-specific memory T cells.

IL-2 rescues antigen-specific T cells from radiation or dexamethasone-induced apoptosis. Correlation with induction of Bcl-2

Most studies of apoptosis on T lymphocytes have examined the effects of various stimuli on immature T cells from the thymus. Previous work has indicated that apoptosis of mature memory T cells may be an important pathophysiologic mechanism in diseases such as AIDS, cancer, and autoimmunity. The effect of IL-2 on apoptosis of T cells is not clear. Therefore, we studied the ability of IL-2 to rescue Ag-specific T cells from apoptosis. We found that IL-2, in a dose-dependent manner, prevented T cells from entering apoptosis induced by gamma-irradiation, mitomycin C, or dexamethasone. This effect was specific for IL-2; IL-1 beta, IL-6, or IFN-gamma could not reproduce it. In contrast to Ag-specific T cells, immature T cells and naive mature peripheral T cells could not be rescued by IL-2 from radiation-induced apoptosis. Apoptosis rescue by IL-2 was associated with the induction of bcl-2 mRNA and protein. This induction could not be attributed to the effects of IL-2 on the cell cycle, as T cells that were prevented from cell cycle progression by irradiation showed a similar induction of bcl-2. Rescued cells retained their Ag-specific proliferative capacity and in vivo functions. These findings demonstrate that the apoptotic death of Ag-specific T cell lines, cells which can be regarded as a model for memory T cells, can be prevented with IL-2. This effect may have important therapeutic implications for patients receiving chemotherapy or radiotherapy, and for patients with AIDS who develop immunodeficiency primarily as a result of loss of Ag-specific memory T cells.

Characterization of the complete genomic structure of the human WNT-5A gene, functional analysis of its promoter, chromosomal mapping, and expression in early human embryogenesis

We report the complete genomic organization of the human WNT-5A gene, which encodes a cysteine-rich growth factor involved in cell-cell signaling during growth and differentiation. The gene comprises five exons with the terminal exon coding for a large 3'-untranslated region of approximately 6.5 kilobase pairs and utilizes multiple polyadenylation signals to generate at least four discrete transcripts. We discovered a new leader exon interrupted by a 411-base pair intron that was retained in our original cDNA cloning. The promoter region was located in a GpC-rich island and harbored numerous cis-acting elements including several GC boxes and Sp1, AP1, and AP2 binding motifs. It lacked TATA or CAAT boxes typical of housekeeping and growth factor genes. In support of this, primer extension revealed extension two transcription start sites. Transient cell transfection assays showed functional promoter activity for the 3.9-kilobase pair 5'-flanking region. Interestingly, internal and 5' deletions revealed tha the distal promoter was not required for full transcriptional activity and that the first 631 base pairs of WNT-5A harbored the strongest promoter activity. Using a panel of rodent-human hybrid DNAs carrying portions of chromosome 3p, we mapped the gene to 3p14.2-p21.1, between a constitutional and a familial renal cell carcinoma-associated translocation. In situ hybridization analyses of early human embryos at 28-42 days of gestation revealed that WNT-5A transcripts were not restricted to the developing brain and limbs but were also observed in the mesenchyme bordering the pharyngeal clefts and pouches and in the developing gonads and kidneys. The relatively high expression in the celomic epithelium and in the precursors of follicles and seminiferous tubules suggest a novel role for WNT-5A in germ-cell differentiation. This study provides the molecular basis for discerning the regulation of the WNT-5A gene and offers the opportunity to investigate genetic disorders linked to this important gene.

Vaccines to prevent and treat autoimmune diseases

The current therapy for human autoimmune disease is based on nonselective immunosuppression achieved by corticosteroids or cytotoxic drugs. This form of therapy is toxic and frequently not effective in curing the disease. The study of experimental autoimmune disease models indicates that the pathogenic population of immune cells is restricted in terms of T-cell receptor gene usage and peptide epitopes recognized in the self-antigens. The recent developments in understanding of the pathophysiology of autoimmune disease point to the crucial role of the pathogenic T cell, the autoantigenic peptide, and the major histocompatibility complex molecules as well as the regulatory T-cell population in the disease process. The purpose of this review is to describe the use of vaccines to prevent and treat autoimmune disease. Encouraging results in animal models using vaccines based on the pathogenic T cell or the autoantigen have prompted the design of novel and selective immune-based therapies for human autoimmune disease.

Induction of diabetes in standard mice by immunization with the p277 peptide of a 60-kDa heat shock protein

We previously reported that immunity to the p277 peptide of the human 60-kDa heat shock protein (hsp60) was a causal factor in the diabetes of non-obese diabetic (NOD) mice, which are genetically prone to develop spontaneous autoimmune diabetes. The present study was done to test whether immunization with the p277 peptide could cause diabetes in standard strains of mice. We now report that a single administration of the p277 peptide conjugated to carrier molecules such as bovine serum albumin or ovalbumin can induce diabetes in C57BL/6 mice and in other strains not genetically prone to develop diabetes. The diabetes was marked by hyperglycemia, insulitis, insulin autoantibodies, glucose intolerance and low blood levels of insulin. The diabetes could be transferred to naive recipients by anti-p277 T cell lines. Similar to other experimentally induced autoimmune diseases, the autoimmune diabetes remitted spontaneously. After recovery, the mice were found to have acquired resistance to a second induction of diabetes. Susceptibility to induced diabetes in C57BL/6 mice was influenced by sex (males were much more susceptible than were females) and by class II genes in the major histocompatibility complex (B6.H-2bm12 mice with a mutation in the MHC-II molecule were relatively resistant). Other strains of mice susceptible to induced diabetes were C57BL/KSJ, C3HeB/FeJ, and NON/Lt. BALB/c and C3H/HeJ strains were relatively resistant. Immunization to p277-carrier conjugates could also induce transient hyperglycemia in young NOD mice, but upon recovery from the induced diabetes, the NOD mice were found to have acquired resistance to later development of spontaneous diabetes. Thus, T cell immunity to the p277 peptide can suffice to induce diabetes in standard mice, and a short bout of induced diabetes can affect the chronic process that would otherwise lead to spontaneous diabetes in diabetes-prone NOD mice.

Pathogenicity of T cells responsive to diverse cryptic epitopes of myelin basic protein in the Lewis rat

The cellular immunology of experimental autoimmune encephalomyelitis, a model for multiple sclerosis, has been studied, for the most part, using T cells directed to dominant epitopes of the Ag myelin basic protein (MBP). To characterize T cells reactive to cryptic epitopes of MBP, we immunized Lewis rats with each of 17 overlapping peptides of the 18.5-kDa isoform of rat MBP. We found that, in addition to the known 71-90 epitope, six other peptides induced active encephalomyelitis in the majority the injected rats. T cell lines raised to six different MBP epitopes were encephalitogenic upon adoptive transfer to naive rats. In contrast to the T cells specific for the dominant 71-90 peptide, the T cell lines reactive to cryptic epitopes were not restricted in their TCR genes to V beta 8.2, and some of the lines caused prolonged disease. Thus, T cells of different specificities and TCR usage can be pathogenic.

Pathogenicity of T cells responsive to diverse cryptic epitopes of myelin basic protein in the Lewis rat

The cellular immunology of experimental autoimmune encephalomyelitis, a model for multiple sclerosis, has been studied, for the most part, using T cells directed to dominant epitopes of the Ag myelin basic protein (MBP). To characterize T cells reactive to cryptic epitopes of MBP, we immunized Lewis rats with each of 17 overlapping peptides of the 18.5-kDa isoform of rat MBP. We found that, in addition to the known 71-90 epitope, six other peptides induced active encephalomyelitis in the majority the injected rats. T cell lines raised to six different MBP epitopes were encephalitogenic upon adoptive transfer to naive rats. In contrast to the T cells specific for the dominant 71-90 peptide, the T cell lines reactive to cryptic epitopes were not restricted in their TCR genes to V beta 8.2, and some of the lines caused prolonged disease. Thus, T cells of different specificities and TCR usage can be pathogenic.

Steroid treatment fails to induce an afternoon luteinizing hormone or prolactin surge in rats exposed to short-term constant light at the time of ovariectomy

The present study investigated the effects of short-term exposure to constant light, initiated at the time of ovariectomy, on the ability of estradiol (E2) treatment alone or in conjunction with progesterone (P) to induce afternoon surges of LH and prolactin (PRL). Adult Fischer 344 rats, which had been ovariectomized (OVX) and placed into constant light (LL) on day 0, were implanted with Silastic capsules containing E2 on day 7 and an atrial cannula on day 8. On the following day (day 9), hourly blood samples were collected between 12.00 and 20.00 h from LL-exposed animals which had received E2 treatment alone or from LL E2-treated animals which had also received P at 12.20 h. Blood samples from control animals which were OVX and treated with E2, but maintained under a 12-hour light:12-hour dark photoperiod, were also collected. Exposure to 9 days of LL abolished the ability of E2 treatment to induce an afternoon surge of LH or PRL. The addition of P treatment to LL E2-treated animals failed to reinstate an LH or PRL surge. While P treatment in LL E2-treated animals induced a rise in PRL levels, it is unlikely, given the timing, duration, and magnitude of PRL release, that this enhancement was initiated by the same mechanisms which normally generate the afternoon surge. The results from the present study demonstrate that short-term exposure to LL, initiated at the time of OVX, abolishes the E2-induced afternoon surges of LH and PRL.

Treatment of autoimmune diabetes and insulitis in NOD mice with heat shock protein 60 peptide p277

We recently showed that a peptide of the M(r) 60,000 heat shock protein molecule, designated peptide p277, is a target of T-cells in autoimmune diabetes in NOD mice. Indeed, the p277 peptide could be used as a therapeutic agent to arrest the autoimmune process even after it was far advanced. The present study was done to document the effects of p277 therapy on inflammation of the islets and on T-cell responsiveness to p277. Groups of female NOD mice of various ages up to 17 weeks were treated with a single inoculation of p277 given before or after the onset of overt hyperglycemia. We now report that fragments of p277 can affect diabetes but that optimal therapy requires the whole peptide. The positive response to p277 was dependent on administration of a threshold dose of peptide. Therapy was accompanied by the regression of intra-islet inflammation and the reappearance of histologically normal islets. Successful peptide therapy was associated with downregulation of T-cell immunity to p277. Adoptive transfer experiments demonstrated that the spleen cells of p277-treated mice were no longer diabetogenic and also could suppress the diabetogenic potential of cotransferred spleen cells of untreated female NOD mice. These results indicate that specific treatment of diabetes with a defined peptide can reprogram the autoimmune response.

Functional activation of encephalitogenic T cells in the absence of antigen-presenting cells

Co-stimulatory signals provided by surface receptors of antigen-presenting cells (APC) are crucial for the activation of CD4+ T cells, classically measured by cell proliferation or IL-2 secretion. The contribution of APC co-stimulatory signals to the acquisition of various effector functions by activated T cells is not fully understood. We have now examined the importance of surface-mediated co-stimulation by APC for activation of the effector potential of T cell clones mediating experimental allergic encephalomyelitis (EAE). We now report that T cell clones can be activated to produce EAE not only with APC but also by antibody-mediated TCR cross-linking in the presence of a mixture of T cell growth factors. Without activation, the T cell clones did not cause EAE. Therefore, at least some types of T cells can be activated to express their effector potential in the absence of any surface co-stimulatory signals requiring intact APC.

Self and foreign 60-kilodalton heat shock protein T cell epitope peptides serve as immunogenic carriers for a T cell-independent sugar antigen

Healthy individuals manifest natural T cell reactivity to epitopes of the 60-kDa heat shock protein (hsp60) of both self and bacterial origin. The present studies were done to learn whether defined peptides of hsp60 could function as T cell carrier epitopes for a poorly immunogenic T-independent capsular polysaccharide, the Vi Ag of Salmonella typhi. Homologous peptides were synthesized from the mouse self-hsp60 molecule (CP1m), from the closely related human hsp60 molecule (CP1h), and from the more distant Escherichia coli (CP1ec) and mycobacterial (CP1mt) hsp60 molecules. The peptides were conjugated to Vi and tested for their immunogenicity in BALB/c (H-2d) and H-2 congenic mice (H-2k and H-2b). We now report that the self-CP1m and cross-reactive CP1h peptides were as immunogenic as was the non-cross-reactive foreign CP1ec peptide. Small amounts of the CP1 peptide, even in PBS, sufficed to induce anti-Vi Abs of the IgG1 (T-dependent) isotype in naive mice. The carrier effect was associated with the ability of the peptides to bind to APC and to induce T cell proliferation. H-2d and H-2k mice, but not H-2b mice responded to CP1m/h and CP1ec. None of the mice responded to CP1mt. No signs of inflammation or autoimmune disease were detected. Thus, natural T cell autoimmunity exists and can be harnessed to provide T cell help for Ab production to a foreign bacterial molecule in a synthetic vaccine.

Self and foreign 60-kilodalton heat shock protein T cell epitope peptides serve as immunogenic carriers for a T cell-independent sugar antigen

Healthy individuals manifest natural T cell reactivity to epitopes of the 60-kDa heat shock protein (hsp60) of both self and bacterial origin. The present studies were done to learn whether defined peptides of hsp60 could function as T cell carrier epitopes for a poorly immunogenic T-independent capsular polysaccharide, the Vi Ag of Salmonella typhi. Homologous peptides were synthesized from the mouse self-hsp60 molecule (CP1m), from the closely related human hsp60 molecule (CP1h), and from the more distant Escherichia coli (CP1ec) and mycobacterial (CP1mt) hsp60 molecules. The peptides were conjugated to Vi and tested for their immunogenicity in BALB/c (H-2d) and H-2 congenic mice (H-2k and H-2b). We now report that the self-CP1m and cross-reactive CP1h peptides were as immunogenic as was the non-cross-reactive foreign CP1ec peptide. Small amounts of the CP1 peptide, even in PBS, sufficed to induce anti-Vi Abs of the IgG1 (T-dependent) isotype in naive mice. The carrier effect was associated with the ability of the peptides to bind to APC and to induce T cell proliferation. H-2d and H-2k mice, but not H-2b mice responded to CP1m/h and CP1ec. None of the mice responded to CP1mt. No signs of inflammation or autoimmune disease were detected. Thus, natural T cell autoimmunity exists and can be harnessed to provide T cell help for Ab production to a foreign bacterial molecule in a synthetic vaccine.