Autoantigen-specific CD4 Research Articles

The dynamics of leukocyte infiltration in experimental autoimmune uveoretinitis

Experimental autoimmune uveoretinitis (EAU) serves as an animal model for human uveitis. EAU is inducible in animals by peripheral immunization with proteins found in the retina that triggers an immune response which leads to tissue damage. This is coordinated by autoantigen specific CD4(+) T cells whose activation is accompanied by the infiltration of a wide range of other leukocytes into the retina. Infiltrating macrophages and granulocytes cause destruction by the release of reactive oxygen and nitrogen species but these and other leukocytes also regulate inflammation. This review will describe the dynamics of leukocyte infiltration in EAU from the initial systemic activation of T cells following immunization, through their traffic into the eye causing a peak of infiltration, and ending with a phase of secondary regulation in which, although clinical disease has resolved, the leukocyte composition of the eye remains altered.

Autoantigen-Specific IL-10-Transduced T Cells Suppress Chronic Arthritis by Promoting the Endogenous Regulatory IL-10 Response

Deficient T cell regulation can be mechanistically associated with development of chronic autoimmune diseases. Therefore, combining the regulatory properties of IL-10 and the specificity of autoreactive CD4(+) T cells through adoptive cellular gene transfer of IL-10 via autoantigen-specific CD4(+) T cells seems an attractive approach to correct such deficient T cell regulation that avoids the risks of nonspecific immunosuppressive drugs. In this study, we studied how cartilage proteoglycan-specific CD4(+) T cells transduced with an active IL-10 gene (T(IL-10)) may contribute to the amelioration of chronic and progressive proteoglycan-induced arthritis in BALB/c mice. TCR-transgenic proteoglycan-specific T(IL-10) cells ameliorated arthritis, whereas T(IL-10) cells with specificity for OVA had no effect, showing the impact of Ag-specific targeting of inflammation. Furthermore, proteoglycan-specific T(IL-10) cells suppressed autoreactive proinflammatory T and B cells, as T(IL-10) cells caused a reduced expression of IL-2, TNF-alpha, and IL-17 and a diminished proteoglycan-specific IgG2a Ab response. Moreover, proteoglycan-specific T(IL-10) cells promoted IL-10 expression in recipients but did not ameliorate arthritis in IL-10-deficient mice, indicating that T(IL-10) cells suppress inflammation by propagating the endogenous regulatory IL-10 response in treated recipients. This is the first demonstration that such targeted suppression of proinflammatory lymphocyte responses in chronic autoimmunity by IL-10-transduced T cells specific for a natural Ag can occur via the endogenous regulatory IL-10 response.

Spontaneous Autoreactive Memory B Cell Formation Driven by a High Frequency of Autoreactive CD4+ T Cells

Although somatically mutated autoantibodies are characteristic of many autoimmune diseases, the processes that can lead to their development remain poorly understood. We have examined the formation of autoreactive memory B cells in PevHA mice, which express the influenza virus PR8 hemagglutinin (HA) as a transgenic membrane bound neo-self-Ag. Using a virus immunization strategy, we show that PR8 HA-specific memory B cell formation can occur in PevHA mice, even though a major subset of PR8 HA-specific B cells is negatively selected from the primary repertoire. Moreover, PR8 HA-specific memory B cells develop spontaneously in TS1 x PevHA mice, which coexpress a transgenic PR8 HA-specific TCR and contain a high frequency of HA-specific CD4(+) T cells. Notably, autoreactive memory B cell formation occurred in TS1 x PevHA mice even though approximately half of the HA-specific CD4(+) T cells were CD25(+)Foxp3(+) cells that could significantly attenuate, but did not completely abolish HA-specific autoantibody production in an adoptive transfer setting. The findings provide evidence that a high frequency of autoreactive CD4(+) T cells can be sufficient to promote autoreactive memory B cell formation in the absence of signals provided by overt immunization or infection and despite the presence of abundant autoantigen-specific CD4(+)CD25(+)Foxp3(+) regulatory T cells.

Abrogation of recurrent autoimmunity in the NOD mouse: A critical role for host interleukin 4

We previously established a clinically relevant strategy to abrogate recurrent autoimmunity and enable long-term islet graft survival, involving antilymphocyte serum (ALS)-depletion of recipient T cells and intraportal administration of donor pancreatic lymph node cells (PLNCs) along with islet grafts. In this study, we investigated whether Th2 cytokines were required for the tolerizing ability of ALS/PLNC treatment in islet transplantation. ALS-treated diabetic NOD recipient mice, and NOD recipient mice deficient in interleukin 4 (IL-4-/-) or 10 (IL-4/10-/-) were transplanted with NOR or NOD.scid islets intraportally along with donor PLNC. Blood glucose levels were monitored to access graft function, sections of graft-bearing livers were histologically examined, and ELISPOT assays were used to assess cytokine profile and frequency of islet-reactive CD4 T cells. We found that ALS/PLNC was not effective in prolonging islet graft survival in diabetic NOD hosts deficient in either IL-4 (NOD.IL-4-/-) or in IL-4 and IL-10 (NOD.IL4-/-/10-/-) (mean survival time, 36 days), contrasting the long-term survival of islet grafts in wild-type NOD mice (mean survival time, > 80 days). In contrast, PLNC deficient in IL-4 promoted long-term graft survival in wild-type NOD hosts similar to that in wild-type PLNC. In wild-type NOD recipients of either wild-type PLNC or IL-4-/- PLNC, the host autoantigen-specific CD4 T cells produced predominately IL-4 coincident with long-term graft survival, whereas, in NOD.IL-4-/- recipients with rejected grafts, the autoreactive T cells produced interferon gamma and low amounts of IL-4. These data demonstrate that abrogation of recurrent autoimmunity requires host IL-4 and that manipulation of the autoreactive cytokine profile in long-term diabetes may be an effective strategy for islet transplant therapies.

Regulatory T Cells Can Mediate Their Function through the Stimulation of APCs to Produce Immunosuppressive Nitric Oxide

Regulatory T cells (Tr cells) play a critical role in inducing immune tolerance. It remains largely unclear how various types of Tr cells perform their regulatory function. We have studied the underlying regulatory mechanism of a population of autoantigen-specific CD4+ Tr cells. These T cells are specific for the glutamic acid decarboxylase p206-220 peptide and are isolated from the diabetes-resistant nonobese-resistant mice. Although these T cells express T-bet and display a Th1 phenotype, they are able to inhibit diabetes. Their regulatory function is dependent on both IFN-gamma and cell contact with target cells. These Tr cells can mediate their cell contact-dependent regulatory function by secreting IFN-gamma which stimulates APCs to produce NO. NO is necessary for the Tr cells to inhibit the proliferation of pathogenic T cells and the development of diabetes. Therefore, we have identified a novel mechanism by which these Tr cells can exert their regulatory function. These results also provide an explanation as to why IFN-gamma may play both pathogenic and immunomodulatory roles in autoimmune diseases.

Visualization of Antigen-specific T Cell in Living Arthritic Mice

It has been shown that CD4 T cells play a crucial role in the pathogenesis of several autoimmune diseases such as rheumatoid arthritis. In fact, CD4 T cells can be found in target organs in both human and mouse models of autoimmunity; thus, autoantigen-specific CD4 T cells have tissue-specific homing properties. However, homing kinetics of such cells in vivo has not been clearly understood. To directly examine whether type II collagen (CII)-specific T cells home to the site of inflammation, we generated T cell hybridomas derived from CII-specific T-cell receptor (TCR)-transgenic mice. We transduced a CII-specific T cell with a gene encoding a green fluorescent protein (GFP)-luciferase fusion protein (termed CII-GFP-Luc), and tested the patterns of cell trafficking with whole-body bioluminescence imaging of the labeled cells in living animals. We injected either CII-GFP-Luc or myelin basic protein (MBP)-specific T cells that carry GFP-luciferase genes (termed MBP-GFP Luc) into mice that had severe arthritis and obtained serial images of the mice. Three days after the cell transfer, photons emitted from the cells were detected in arthritic joints from all mice tested. Interestingly, MBP-GFP-Luc initially homed to inflamed joints as efficiently as did the CII-GFP-Luc cells. However, the trafficking of MBP-GFP-Luc cells to the inflamed joints was transient, whereas the CII-GFP-Luc cells were detected in the arthritic joints for more than 7 days following the injection. These results indicate that both CIIand MBP-specific T cells efficiently trafficked into the inflamed joints, but that TCR specificity seemed to be required for retention of T cells in inflamed joints.

Quantification and characterization of myosin peptide-specific CD4 + T cells in autoimmune myocarditis

Characterization of autoantigen-specific CD4 + T cells at the single cell level is crucial for understanding the immunopathological mechanisms underlying autoimmune diseases. Cardiac myosin heavy chain (myhca) is the major autoantigen associated with autoimmune myocarditis both in humans and in experimental autoimmune myocarditis (EAM) in mice. In the current study, we evaluated two methods for the enumeration and phenotypic characterization of myhca-specific CD4 + T cells during the course of EAM. Both enzyme-linked immunospot (ELISPOT) and cytokine flow cytometry (CFC) assays were suitable for the detection and characterization of myhca-specific Th cells during acute myocardial inflammation and the late healing phase of the disease. Cytokine production of myhca-specific Th cells was restricted to interferon-γ (IFNγ). Only trace amounts of the Th2 cytokines IL-4 and IL-5 could be detected. Concomitant surface marker analysis in the CFC assay revealed the prototypical effector phenotype of myhca-specific Th1 cells during the acute phase of the disease. Taken together, the combination of both methods appears to be most appropriate for a comprehensive ex vivo single cell analysis of Th cells in heart-specific autoimmune disorders.

CD4+CD25+FOXP3+ regulatory T cells from human thymus and cord blood suppress antigen‐specific T cell responses

Activation of self-reactive T cells in healthy adults is prevented by the presence of autoantigen-specific CD4+CD25+ regulatory T cells (CD25+ Treg). To explore the functional development of autoantigen-reactive CD25+ Treg in humans we investigated if thymic CD25+ Treg from children aged 2 months to 11 years and cord blood CD25+ Treg are able to suppress proliferation and cytokine production induced by specific antigens. While CD4+CD25- thymocytes proliferated in response to myelin oligodendrocyte glycoprotein (MOG), tetanus toxoid and beta-lactoglobulin, suppression of proliferation was not detected after the addition of thymic CD25+ Treg. However, CD25+ Treg inhibited interferon (IFN)-gamma production induced by MOG, which indicates that MOG-reactive CD25+ Treg are present in the thymus. In contrast, cord blood CD25+ Treg suppressed both proliferation and cytokine production induced by MOG. Both cord blood and thymic CD25+ Treg expressed FOXP3 mRNA. However, FOXP3 expression was lower in cord blood than in thymic CD25+ T cells. Further characterization of cord blood CD25+ T cells revealed that FOXP3 was highly expressed by CD25+CD45RA+ cells while CD25+CD45RA- cells contained twofold less FOXP3, which may explain the lower expression level of FOXP3 in cord blood CD25+ T cells compared to thymic CD25+ T cells. In conclusion, our data demonstrate that low numbers of MOG-reactive functional CD25+ Treg are present in normal thymus, but that the suppressive ability of the cells is broader in cord blood. This suggests that the CD25+ Treg may be further matured in the periphery after being exported from the thymus.

An efficient method for cloning human autoantigen-specific T cells

T-cell clones are valuable tools for investigating T-cell specificity in infectious, autoimmune and malignant diseases. T cells specific for clinically-relevant autoantigens are difficult to clone using traditional methods. Here we describe an efficient method for cloning human autoantigen-specific CD4 + T cells pre-labelled with CFSE. Proliferating, antigen-responsive CD4 + cells were identified flow cytometrically by their reduction in CFSE staining and single cells were sorted into separate wells. The conditions (cytokines, mitogens and tissue culture plates) for raising T-cell clones were optimised. Media supplemented with IL-2+IL-4 supported growth of the largest number of antigen-specific clones. Three mitogens, PHA, anti-CD3 and anti-CD3+anti-CD28, each stimulated the growth of similar numbers of antigen-specific clones. Cloning efficiency was similar in flat- and round-bottom plates. Based on these findings, IL-2+IL-4, anti-CD3 and round-bottom plates were used to clone FACS-sorted autoantigen-specific CFSE-labelled CD4 + T cells. Sixty proinsulin- and 47 glutamic acid decarboxylase-specific clones were obtained from six and two donors, respectively. In conclusion, the CFSE-based method is ideal for cloning rare, autoantigen-specific, human CD4 + T cells.

Immunotherapy for the Prevention and Treatment of Type 1 Diabetes

A major effort has been on-going to develop immunotherapies to prevent and/or treat type 1 diabetes (T1D). This autoimmune disease is characterized by the selective loss of the insulin-producing β cells via the cumulative effects of autoantigen-specific CD4+ and CD8+ T cells, autoantibodies, and activated antigen-presenting cells. To be applicable in a clinical setting, immunotherapies must suppress established β-cell autoimmunity. Preclinical studies and recent clinical findings suggest that antigen-specific and systemic-based strategies can be effective in this regard. However, either approach alone may not be sufficient to block the diabetogenic response and establish long-term protection in the clinic. In this review, we will discuss the importance of both strategies and how a combinatorial approach to treat T1D is appealing.

CD4+ T Cell Proliferation in Response to GAD and Proinsulin in Healthy, Pre‐diabetic, and Diabetic Donors

The ability to measure proliferation of autoantigen-specific T cells is critical for the evaluation of cellular immune function. Using a novel, sensitive, CFSE-based assay, we were able to directly quantitate autoantigen-specific CD4(+) T cell proliferation. However, peripheral blood cells from healthy, pre-diabetic and diabetic donors exhibited overlap in responses to glutamic acid decarboxylase (GAD65) and proinsulin (PI). This indicates that autoantigen-induced CD4(+) T cell proliferation in a functionally complex cell population may not discriminate disease in the general population. Clear discrimination was found between diabetic and healthy sibs, suggesting the need to standardize the genetic and environmental background. In addition, the ability of the CFSE assay to allow analysis of the phenotype and function of autoantigen-responsive T cells may improve discrimination.

Myelin proteolipid protein-specific CD4+CD25+ regulatory cells mediate genetic resistance to experimental autoimmune encephalomyelitis.

SJL mice are highly susceptible to experimental autoimmune encephalomyelitis (EAE) induced with myelin proteolipid protein (PLP) peptide 139-151, whereas H-2 congenic B10.S mice are resistant. Immunodominance and susceptibility to EAE are associated with a high precursor frequency of PLP 139-151-specific T cells in the naive repertoire of SJL mice. To understand the mechanism of EAE resistance in B10.S mice, we determined the precursor frequency of PLP 139-151-reactive T cells in both strains by using IAs/PLP 139-151 tetramers. SJL and B10.S mice had similar frequencies of tetramer-reactive T cells in the naive peripheral repertoire. However, in SJL mice, the majority of PLP 139-151 tetramer-positive cells were in the CD4+CD25- population, whereas there were more tetramer-positive cells in the CD4+CD25+ population of B10.S mice. Depletion of CD4+CD25+ cells in vivo facilitated the expansion of PLP 139-151-reactive cells with production of T helper 1 cytokines in EAE-resistant B10.S mice. Furthermore, anti-CD25 Ab treatment before immunization resulted in EAE induction in these otherwise resistant mice. These data indicate an important role for autoantigen-specific CD4+CD25+ cells in genetic resistance to autoimmunity.

Development of autoimmune exocrinopathy resembling Sjögren's syndrome in adoptively transferred mice with autoreactive CD4+ T cells.

The pathologic mechanisms responsible for organ-specific tissue damage in primary Sjögren's syndrome (SS) remain unclear, but it has been suggested that the pathology is mediated by autoreactive CD4+ T cells infiltrating the salivary and lacrimal glands. This study was undertaken to investigate whether alpha-fodrin autoantigen-specific autoreactive CD4+ T cells are capable of inducing autoimmune lesions. A total of 45 synthetic alpha-fodrin peptides designed to be 20 amino acid residues in length were generated. To establish an autoreactive T cell line, limiting dilution analysis (LDA) was performed on lymph node cells (LNCs) in the presence of alpha-fodrin peptides. The effects of adoptive transfer of autoreactive CD4+ T cells into normal syngeneic recipients were investigated. Autoreactive CD4+ T cell lines that recognize synthetic alpha-fodrin peptide, which produced Th1 cytokines and showed cytotoxic activities, were established in a murine model for SS. T cell receptor V(beta) usage and third complementarity-determining region (CDR3) sequences indicated that in some cases V(beta)6-CDR3 genes matched between the tissue-infiltrating T cells and the autoreactive T cell lines. Adoptive transfer of the autoreactive CD4+ T cells into normal syngeneic recipients induced autoimmune lesions quite similar to those of SS. Our data help to elucidate the pathogenic mechanisms responsible for tissue destruction in autoimmune exocrinopathy and indicate that autoreactive CD4+ T cells play a pivotal role in the development of murine SS.

LF 15-0195 inhibits the development of rat central nervous system autoimmunity by inducing long-lasting tolerance in autoreactive CD4 T cells.

Experimental autoimmune encephalomyelitis (EAE) is a T cell-dependent autoimmune disease induced in susceptible animals by a single immunization with myelin basic protein (MBP). LF 15-0195 is a novel immunosuppressor that has been shown to have a potent immunosuppressive effect in several pathological manifestations. The purpose of this study was to investigate the effect of this drug on the induction and progression of established rat EAE and to dissect the mechanisms involved. We show that LF 15-0195 administration at the time of MBP immunization reduces the incidence and severity of EAE in Lewis rats. This drug also inhibits ongoing and passively induced EAE, indicating that LF 15-0195 affects already differentiated pathogenic lymphocytes. Compared with lymph node cells from untreated rats, lymphocytes from MBP-immunized rats treated with LF 15-0195 proliferated equally well in response to MBP in vitro, while their ability to produce effector cytokines and to transfer EAE into syngeneic recipients was significantly reduced. This phenomenon is stable and long-lasting. Indeed, neither IL-12 nor repeated stimulation with naive APC and MBP in vitro rendered MBP-specific CD4 T cells from protected rats encephalitogenic. In conclusion, LF 15-0195 treatment suppresses EAE by interfering with both the differentiation and effector functions of autoantigen-specific CD4 T cells.

Suppression of autoreactive T-cell response to glycoprotein IIb/IIIa by blockade of CD40/CD154 interaction: implications for treatment of immune thrombocytopenic purpura

The potential immunosuppressive effect of an anti-CD154 monoclonal antibody (mAb) on the pathogenic autoreactive T-cell response was evaluated using an in vitro culture system with glycoprotein IIb/IIIa (GPIIb/IIIa)-reactive T cells from patients with immune thrombocytopenic purpura (ITP). The anti-CD154 mAb did not inhibit T-cell proliferation, but suppressed anti-GPIIb/IIIa antibody production, in bulk peripheral blood mononuclear cell cultures stimulated with GPIIb/IIIa. Repeated antigenic stimulation of GPIIb/IIIa-reactive CD4(+) T-cell lines in the presence of anti-CD154 mAb resulted in the loss of proliferative capacity and helper function for promoting anti-GPIIb/IIIa antibody production. These anergic T-cell lines showed a cytokine profile of low interferon gamma and high interleukin 10 and suppressed anti-GPIIb/IIIa antibody production. Our results indicate that blockade of the CD40/CD154 interaction induces generation of autoantigen-specific anergic CD4(+) T cells with regulatory function and could be a therapeutic option for suppressing pathogenic autoimmune responses in patients with ITP.

Possible role of organ-specific autoantigen for Fas ligand-mediated activation-induced cell death in murine Sjögren's syndrome.

Activation-induced cell death (AICD) is a well-known mechanism of peripheral T cell tolerance that depends upon an interaction between Fas and Fas ligand (FasL). In this study, we demonstrate that the administration of a soluble form of anti-FasL Ab, FLIM58, results in severe destructive autoimmune exocrinopathy in the murine model of human Sjögren's syndrome (SS), and we found that an organ-specific autoantigen may play an important role on down-modulation of AICD. A high titer of serum autoantibodies against 120-kDa alpha-fodrin autoantigen was detected in the FLIM58-treated mice, and splenic T cell culture supernatants contained high levels of IFN-gamma. In vitro T cell apoptosis assay indicated that FasL-mediated AICD is down-regulated by autoantigen stimulation in spleen cells from the murine SS model, but not from Fas-deficient MRL/lpr mice and FasL-deficient MRL/gld mice. FasL undergo metalloproteinase-mediated proteolytic processing in their extracellular domains, resulting in the release of soluble trimeric ligands (soluble FasL). We showed that the processing of soluble FasL occurs in autoantigen-specific CD4(+) T cells, and that a significant increase in expressions of metalloproteinase-9 mRNA was observed in spleen cells from SS model mice. These findings indicate that the increased generation of soluble FasL inhibits the normal AICD process, leading to the proliferation of effector CD4(+) T cells in the murine SS model.

Adoptive immunotherapy of experimental autoimmune encephalomyelitis via T cell delivery of the IL-12 p40 subunit.

CD4+ T cells are believed to play a central role in the initiation and perpetuation of autoimmune diseases such as multiple sclerosis. In the murine model for multiple sclerosis, experimental autoimmune encephalomyelitis, pathogenic T cells exhibit a Th1-like phenotype characterized by heightened expression of proinflammatory cytokines. Systemic administration of "regulatory" cytokines, which serve to counter Th1 effects, has been shown to ameliorate autoimmune responses. However, the inherent problems of nonspecific toxicity limit the usefulness of systemic cytokine delivery as a potential therapy. Therefore, we used the site-specific trafficking properties of autoantigen-reactive CD4+ T cells to develop an adoptive immunotherapy protocol that provided local delivery of a Th1 cytokine antagonist, the p40 subunit of IL-12. In vitro analysis demonstrated that IL-12 p40 suppressed IFN-gamma production in developing and effector Th1 populations, indicating its potential to modulate Th1-promoted inflammation. We have previously demonstrated that transduction of myelin basic protein-specific CD4+ T cells with pGC retroviral vectors can result in efficient and stable transgene expression. Therefore, we adoptively transferred myelin basic protein-specific CD4+ T cells transduced to express IL-12 p40 into mice immunized to develop experimental autoimmune encephalomyelitis and demonstrated a significant reduction in clinical disease. In vivo tracking of bioluminescent lymphocytes, transduced to express luciferase, using low-light imaging cameras demonstrated that transduced CD4+ T cells trafficked to the central nervous system, where histological analysis confirmed long-term transgene expression. These studies have demonstrated that retrovirally transduced autoantigen-specific CD4+ T cells inhibited inflammation and promoted immunotherapy of autoimmune disorders.

Targeting rare populations of murine antigen-specific T lymphocytes by retroviral transduction for potential application in gene therapy for autoimmune disease.

CD4+ T cells are important mediators in the pathogenesis of autoimmunity and would therefore provide ideal candidates for lymphocyte-based gene therapy. However, the number of Ag-specific T cells in any single lesion of autoimmunity may be quite low. Successful gene transfer into autoantigen-specific CD4+ T cells would serve as an ideal vehicle for site-targeted gene therapy if it were possible to transduce preferentially the small number of autoantigen-specific T cells. In this study we have demonstrated that retroviral infection of CD4+ lymphocytes from either autoantigen-stimulated TCR transgenic mice, or Ag-activated immunized nontransgenic mice, with a retroviral vector (pGCIRES), resulted in the transduction of only the limited number of Ag-reactive CD4+ T cells. In contrast, polyclonal activation of the same cultures resulted in transduction of non-antigen-specific lymphocytes. Transduction of Ag-reactive CD4+ T cells with pGCIRES retrovirus encoding the regulatory genes IL-4 (IL4) and soluble TNF receptor (STNFR) resulted in stable integration and long-term expression of recombinant gene products. Moreover, expression of the pGCIRES marker protein, GFP, directly correlated with the expression of the upstream regulatory gene. Retroviral transduction of CD4+ T cells targeted specifically Ag-reactive cells and was cell cycle-dependent and evident only during the mitosis phase. These studies suggest that retroviral transduction of autoantigen-specific murine CD4+ T cells, using the pGCIRES retroviral vector, may provide a potential method to target and isolate the low frequency of autoantigen-specific murine CD4+ T cells, and provides a rational approach to gene therapy in animal models of autoimmunity.

Gene therapy for autoimmune disease.

Autoantigen-specific CD4(+) T lymphocytes have been implicated in the pathogenesis of autoimmune diseases. Tissue-specific homing properties of autoantigen-specific CD4(+) T cells suggested that these cells might be ideal vehicles for delivery of retroviral-encoded regulatory proteins in a site-specific manner as a therapy for autoimmune diseases. Application of retroviral transduction of autoantigen-reactive CD4(+) T cells in gene therapy of autoimmunity must include systems capable of targeting these rare populations of antigen-activated T cells. Studies discussed below suggest that retroviral transduction of autoantigen-specific murine CD4(+) T cells may provide a method to target and isolate nontransformed autoantigen-specific murine CD4(+) T cells and provide a rational approach to gene therapy in animal models of autoimmunity.

Cytokine secretion profile of myelin basic protein-specific T cells in multiple sclerosis.

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system with a presumed autoimmune pathogenesis involving autoantigen-specific CD4+ T cells and cytokines. A similar frequency of T cells responding to myelin basic protein (MBP), a putative target in MS, has been observed in MS patients and controls. To dissect the differences between MBP-specific T cells in patients and controls, we have analyzed the cytokine secretion profile of such autoreactive T cells. MBP-specific T cell clones (TCC) were isolated from the peripheral blood of MS patients and controls by limiting dilution. Expression of mRNA for interferon-gamma (IFN-gamma), interleukin (IL)-4, IL-10, tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) was assessed by polymerase chain reaction whereas secretion of cytokine protein was measured by ELISA. MBP-specific TCC exhibited a heterogeneous cytokine secretion profile with clones displaying Th1, Th2 and Th0 phenotypes. A significant difference in the distribution of the cytokine profile was noted between MS patients and controls. Although the frequency of Th1 secreting MBP-reactive TCC was similar between MS patients and controls, stable MS patients had a significant association with the Th0 phenotype whereas healthy individuals were associated with the Th2 phenotype. In comparison to control TCC, MBP-specific TCC from MS patients secreted increased amounts of IFN-gamma, IL-4 and IL-10 and decreased quantities of TGF-beta. Thus, these studies suggest that there is a dysregulation in the balance between pro-inflammatory Th1 and anti-inflammatory Th2 cytokines in MS. It appears that the presence of Th1 secreting autoreactive T cells in healthy individuals may be counterbalanced by the presence of cells secreting Th2 cytokines and by the augmented production of the immunosuppressive cytokine TGF-beta, whereas in MS there is a decrease in these anti-inflammatory agents.