Shared human T cell receptor V beta usage to immunodominant regions of myelin basic protein

Driving CARs to BARs: The Winding Road to Specific Regulatory T Cells for Tolerance

Chimeric antigen receptor (CAR) transduced T cells have significantly improved cancer immunotherapy. Similarly, engineering regulatory T cells (Treg) with specific receptors to endow specificity and increase efficacy of Tregs holds great promise for therapy of a variety of adverse immune responses. In this review, we focus on our approaches using retroviral transduction of specific T-cell receptors, single chain variable fragments (scFv) or antigen in models of monogenic diseases, autoimmunity and allergy. The advantages of each of these for different targets diseases are discussed as well as their potential for clinical translation.

Engineered MBP-specific human Tregs ameliorate MOG-induced EAE through IL-2-triggered inhibition of effector T cells

Expanded polyclonal T regulatory cells (Tregs) offer great promise for the treatment of immune-mediated diseases. Inhibition by Tregs is under the control of the T-cell receptor (TCR). Therefore, we created Tregs with defined antigen specificity, using a recombinant T-cell receptor isolated from a myelin-basic protein specific T-cell clone of a multiple sclerosis (MS) patient (Ob2F3). We expressed this TCR using a retroviral expression vector in human Tregs from peripheral blood. We observed that transduced Tregs were activated in vitro in response to myelin basic protein (MBP) peptide on DR15 antigen-presenting cells (APC) and upregulated Treg markers, Foxp3, LAP and Helios. These engineered MBP-specific Tregs could suppress MBP-specific T effector cells, and were also able to suppress T cells with other specificities after Tregs had been activated through the TCR. Importantly, we showed that these engineered Tregs were able to function effectively in the presence of strong TLR-induced inflammatory signals, and that MBP-specific Tregs ameliorated EAE in myelin oligodendrocyte glycoprotein (MOG)-immunized DR15 transgenic mice. We further demonstrated in vitro that IL-2 produced by neighboring effector T cells activated MBP-specific Tregs, initiating contact-independent suppression to T effectors in local milieu. Mechanistic studies demonstrated that bystander suppression in vivo may involve transfer of soluble mediators, enhanced by cell contact between Tregs and effectors. Taken together, we show that engineered clonal MBP-specific Tregs are able to suppress autoimmune pathology in EAE. This approach may serve as a cellular therapy for MS patients with the common DR15 haplotype that is associated with disease susceptibility.

History, applications, and challenges of immune repertoire research

The diversity of T and B cells in terms of their receptor sequences is huge in the vertebrate's immune system and provides broad protection against the vast diversity of pathogens. Immune repertoire is defined as the sum of T cell receptors and B cell receptors (also named immunoglobulin) that makes the organism's adaptive immune system. Before the emergence of high-throughput sequencing, the studies on immune repertoire were limited by the underdeveloped methodologies, since it was impossible to capture the whole picture by the low-throughput tools. The massive paralleled sequencing technology suits perfectly the researches on immune repertoire. In this article, we review the history of immune repertoire studies, in terms of technologies and research applications. Particularly, we discuss several aspects of challenges in this field and highlight the efforts to develop potential solutions, in the era of high-throughput sequencing of the immune repertoire.

Human Tregs Made Antigen Specific by Gene Modification: The Power to Treat Autoimmunity and Antidrug Antibodies with Precision

Human regulatory CD4⁺ T cells (Tregs) are potent immunosuppressive lymphocytes responsible for immune tolerance and homeostasis. Since the seminal reports identifying Tregs, vast research has been channeled into understanding their genesis, signature molecular markers, mechanisms of suppression, and role in disease. This research has opened the doors for Tregs as a potential therapeutic for diseases and disorders such as multiple sclerosis, type I diabetes, transplantation, and immune responses to protein therapeutics, like factor VIII. Seminal clinical trials have used polyclonal Tregs, but the frequency of antigen-specific Tregs among polyclonal populations is low, and polyclonal Tregs may risk non-specific immunosuppression. Antigen-specific Treg therapy, which uses genetically modified Tregs expressing receptors specific for target antigens, greatly mitigates this risk. Building on the principles of T-cell receptor cloning, chimeric antigen receptors (CARs), and a novel CAR derivative, called B-cell antibody receptors, our lab has developed different types of antigen-specific Tregs. This review discusses the current research and optimization of gene-modified antigen-specific human Tregs in our lab in several disease models. The preparations and considerations for clinical use of such Tregs also are discussed.

Antibodies to influenza nucleoprotein cross-react with human hypocretin receptor 2

The sleep disorder narcolepsy is linked to the HLA-DQB1*0602 haplotype and dysregulation of the hypocretin ligand-hypocretin receptor pathway. Narcolepsy was associated with Pandemrix vaccination (an adjuvanted, influenza pandemic vaccine) and also with infection by influenza virus during the 2009 A(H1N1) influenza pandemic. In contrast, very few cases were reported after Focetria vaccination (a differently manufactured adjuvanted influenza pandemic vaccine). We hypothesized that differences between these vaccines (which are derived from inactivated influenza viral proteins) explain the association of narcolepsy with Pandemrix-vaccinated subjects. A mimic peptide was identified from a surface-exposed region of influenza nucleoprotein A that shared protein residues in common with a fragment of the first extracellular domain of hypocretin receptor 2. A significant proportion of sera from HLA-DQB1*0602 haplotype-positive narcoleptic Finnish patients with a history of Pandemrix vaccination (vaccine-associated narcolepsy) contained antibodies to hypocretin receptor 2 compared to sera from nonnarcoleptic individuals with either 2009 A(H1N1) pandemic influenza infection or history of Focetria vaccination. Antibodies from vaccine-associated narcolepsy sera cross-reacted with both influenza nucleoprotein and hypocretin receptor 2, which was demonstrated by competitive binding using 21-mer peptide (containing the identified nucleoprotein mimic) and 55-mer recombinant peptide (first extracellular domain of hypocretin receptor 2) on cell lines expressing human hypocretin receptor 2. Mass spectrometry indicated that relative to Pandemrix, Focetria contained 72.7% less influenza nucleoprotein. In accord, no durable antibody responses to nucleoprotein were detected in sera from Focetria-vaccinated nonnarcoleptic subjects. Thus, differences in vaccine nucleoprotein content and respective immune response may explain the narcolepsy association with Pandemrix.

In vivo maintenance of human regulatory T cells during CD25 blockade

Regulatory T cells (Tregs) mediate immune tolerance to self and depend on IL-2 for homeostasis. Treg deficiency, dysfunction, and instability are implicated in the pathogenesis of numerous autoimmune diseases. There is considerable interest in therapeutic modulation of the IL-2 pathway to treat autoimmunity, facilitate transplantation tolerance, or potentiate tumor immunotherapy. Daclizumab is a humanized mAb that binds the IL-2 receptor a subunit (IL-2R a or CD25) and prevents IL-2 binding. In this study, we investigated the effect of daclizumab-mediated CD25 blockade on Treg homeostasis in patients with relapsing-remitting multiple sclerosis. We report that daclizumab therapy caused an ~50% decrease in Tregs over a 52-wk period. Remaining FOXP3+ cells retained a demethylated Treg-specific demethylated region in the FOXP3 promoter, maintained active cell cycling, and had minimal production of IL-2, IFN- g, and IL-17. In the presence of daclizumab, IL-2 serum concentrations increased and IL-2R bg signaling induced STAT5 phosphorylation and sustained FOXP3 expression. Treg declines were not associated with daclizumab-related clinical benefit or cutaneous adverse events. These results demonstrate that Treg phenotype and lineage stability can be maintained in the face of CD25 blockade.

High-throughput sequencing of immune repertoires in multiple sclerosis

T cells and B cells are crucial in the initiation and maintenance of multiple sclerosis (MS), and the activation of these cells is believed to be mediated through specific recognition of antigens by the T‐ and B‐cell receptors. The antigen receptors are highly polymorphic due to recombination (T‐ and B‐cell receptors) and mutation (B‐cell receptors) of the encoding genes, which can therefore be used as fingerprints to track individual T‐ and B‐cell clones. Such studies can shed light on mechanisms driving the immune responses and provide new insights into the pathogenesis. Here, we summarize studies that have explored the T‐ and B‐cell receptor repertoires using earlier methodological approaches, and we focus on how high‐throughput sequencing has provided new knowledge by surveying the immune repertoires in MS in even greater detail and with unprecedented depth.

The re-emergence of antigen-specific tolerance as a potential therapy for MS

Ideal therapy for inflammatory disease in the nervous system would preserve normal immune function, while suppressing only the pathologic immune responses that damage tissue and allowing for repair. In principle, antigen-specific therapy would eradicate unwanted adaptive immune responses-antibody and T-cell mediated--while preserving the integrity of other adaptive responses to infectious agents and retaining the ability to fight malignancy. However, at this time, for multiple sclerosis (MS) we do not have compelling evidence that would support any particular dominant immune response to any specific antigen or even a limited group of antigens. In fact, there are adaptive immune responses to a wide swathe of proteins and lipids found on neurons and myelin in MS. Unless controlling a few of the known immune responses is sufficient, antigen-specific therapy in MS may not have enough of an impact to modulate clinical outcome. However, in other neuroinflammatory conditions, such as neuromyelitis optica, the adaptive immune response is highly focused. Trials of antigen-specific therapy for neuroinflammatory disease might first be tested in diseases with a more limited adaptive immune response like neuromyelitis optica. The likelihood of a significant success for this therapeutic strategy might then ensue.

Oxidative and Nitrosative Stress and Immune-Inflammatory Pathways in Patients with Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS)

Myalgic Encephalomyelitis (ME) / Chronic Fatigue Syndrome (CFS) has been classified as a disease of the central nervous system by the WHO since 1969. Many patients carrying this diagnosis do demonstrate an almost bewildering array of biological abnormalities particularly the presence of oxidative and nitrosative stress (O&NS) and a chronically activated innate immune system. The proposal made herein is that once generated chronically activated O&NS and immune-inflammatory pathways conspire to generate a multitude of self-sustaining and self-amplifying pathological processes which are associated with the onset of ME/CFS. Sources of continuous activation of O&NS and immune-inflammatory pathways in ME/CFS are chronic, intermittent and opportunistic infections, bacterial translocation, autoimmune responses, mitochondrial dysfunctions, activation of the Toll-Like Receptor Radical Cycle, and decreased antioxidant levels. Consequences of chronically activated O&NS and immune-inflammatory pathways in ME/CFS are brain disorders, including neuroinflammation and brain hypometabolism / hypoperfusion, toxic effects of nitric oxide and peroxynitrite, lipid peroxidation and oxidative damage to DNA, secondary autoimmune responses directed against disrupted lipid membrane components and proteins, mitochondrial dysfunctions with a disruption of energy metabolism (e.g. compromised ATP production) and dysfunctional intracellular signaling pathways. The interplay between all of these factors leads to self-amplifying feed forward loops causing a chronic state of activated O&NS, immune-inflammatory and autoimmune pathways which may sustain the disease.

Measuring T cell receptor and T cell gene expression diversity in antigen-responsive human CD4+ T cells

T cells have diversity in TCR, epitope recognition, and cytokine production, and can be used for immune monitoring. Furthermore, clonal expansion of TCR families in disease may provide opportunities for TCR-directed therapies. We developed methodology for sequencing expressed genes of TCR alpha and beta chains from single cells and applied this to vaccine (tetanus-toxoid)-responsive CD4(+) T cells. TCR alpha and beta chains were both successfully sequenced in 1309 (43%) of 3038 CD4(+) T cells yielding 677 different receptors. TRAV and TRBV gene usage differed between tetanus-toxoid-responsive and non-responsive cells (p=0.004 and 0.0002), and there was extensive TCR diversity in tetanus-toxoid-responsive cells within individuals. Identical TCRs could be recovered in different samples from the same subject: TCRs identified after booster vaccination were frequent in pre-booster memory T cells (31% of pre-booster TCR), and also identified in pre-booster vaccination naïve cells (6.5%). No TCR was shared between subjects, but tetanus toxoid-responsive cells sharing one of their TCR chains were observed within and between subjects. Coupling single-cell gene expression profiling to TCR sequencing revealed examples of distinct cytokine profiles in cells bearing identical TCR. Novel molecular methodology demonstrates extensive diversity of Ag-responsive CD4(+) T cells within and between individuals.

The emerging role of autoimmunity in myalgic encephalomyelitis/chronic fatigue syndrome (ME/cfs)

The World Health Organization classifies myalgic encephalomyelitis/chronic fatigue syndrome (ME/cfs) as a nervous system disease. Together with other diseases under the G93 heading, ME/cfs shares a triad of abnormalities involving elevated oxidative and nitrosative stress (O&NS), activation of immuno-inflammatory pathways, and mitochondrial dysfunctions with depleted levels of adenosine triphosphate (ATP) synthesis. There is also abundant evidence that many patients with ME/cfs (up to around 60 %) may suffer from autoimmune responses. A wide range of reported abnormalities in ME/cfs are highly pertinent to the generation of autoimmunity. Here we review the potential sources of autoimmunity which are observed in people with ME/cfs. The increased levels of pro-inflammatory cytokines, e.g., interleukin-1 and tumor necrosis factor-α, and increased levels of nuclear factor-κB predispose to an autoimmune environment. Many cytokine abnormalities conspire to produce a predominance of effector B cells and autoreactive T cells. The common observation of reduced natural killer cell function in ME/cfs is a source of disrupted homeostasis and prolonged effector T cell survival. B cells may be pathogenic by playing a role in autoimmunity independent of their ability to produce antibodies. The chronic or recurrent viral infections seen in many patients with ME/cfs can induce autoimmunity by mechanisms involving molecular mimicry and bystander activation. Increased bacterial translocation, as observed in ME/cfs, is known to induce chronic inflammation and autoimmunity. Low ATP production and mitochondrial dysfunction is a source of autoimmunity by inhibiting apoptosis and stimulating necrotic cell death. Self-epitopes may be damaged by exposure to prolonged O&NS, altering their immunogenic profile and become a target for the host's immune system. Nitric oxide may induce many faces of autoimmunity stemming from elevated mitochondrial membrane hyperpolarization and blockade of the methionine cycle with subsequent hypomethylation of DNA. Here we also outline options for treatment involving rituximab and endotherapia.

Biased usage and preferred pairing of α- and β-chains of TCRs specific for an immunodominant gluten epitope in coeliac disease

CD4⁺ T cells that recognize dietary gluten antigens presented by the disease-associated HLA-DQ2 or DQ8 molecules are central players in coeliac disease. Unbiased sequencing of the human TCRα variable (TRAV) and humanTCRβ variable (TRBV) genes of 68 HLA-DQ2.5-glia-α2-specific T cells from coeliac disease patients confirmed previous reports of over-usage of the TRBV7-2 gene segment, a conserved Arg residue in the complementarity-determining region (CDR) 3β loop and prevalent usage of the canonical ASSxRxTDTQY CDR3β loop among T cells with this specificity. In 30 clones that had the canonical TCRβ chain, we found a strict usage of the TRAV26-1 gene segment in the TCRα chain. There was variable usage of the TRAJ genes and diverse CDR3α sequences with no apparent conserved motifs. This study extends previous reports on biased TCR usage in both HLA-DQ2.5- and DQ8-restricted gluten-specific TCRs and provides data for further studies on TRAV and TRBV pairing.

Is multiple sclerosis an autoimmune disease?

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) with varied clinical presentations and heterogeneous histopathological features. The underlying immunological abnormalities in MS lead to various neurological and autoimmune manifestations. There is strong evidence that MS is, at least in part, an immune-mediated disease. There is less evidence that MS is a classical autoimmune disease, even though many authors state this in the description of the disease. We show the evidence that both supports and refutes the autoimmune hypothesis. In addition, we present an alternate hypothesis based on virus infection to explain the pathogenesis of MS.

T cell clonal expansions detected in patients with primary biliary cirrhosis express CX3CR1

The intrahepatic biliary destruction of primary biliary cirrhosis (PBC) appears secondary to a multi-lineage response that includes autoantibodies, biliary apotopes, and cellular responses. Although there has been considerable effort in defining the role and specificity of anti-mitochondrial autoantibodies, a major challenge has been the characterization of T effector pathways. This difficulty is due in part to the limitation of current technologies for directly isolating and characterizing autoreactive T cells from patients. Herein, we successfully demonstrate a novel technology for characterizing the surface phenotype of T cell oligoclonal expansions directly ex vivo. Using PBC as a prototypic disease we were able to detect clonal T cell expansions in 15/15 patients examined. Although the T cell expansions from different patients expressed different TCRVβ gene segments, the surface phenotype of the cells was the same. The clonal T cell expansions in PBC patients are CX3CR1(+) Fas(+) effector-memory T cells, a finding of particular importance given the known up-regulation of fractalkine on injured biliary epithelial cells (BEC). In contrast to the persistent aberrantly expanded T cells observed in the PBC patients, T cell expansions detected in response to a herpes viral infection were very dynamic and resolved over time. This protocol can be used to characterize T cell expansions in other autoimmune diseases.

Bias in the αβ T-cell repertoire: implications for disease pathogenesis and vaccination

The naïve T-cell repertoire is vast, containing millions of unique T-cell receptor (TCR) structures. Faced with such diversity, the mobilization of TCR structures from this enormous pool was once thought to be a stochastic, even chaotic, process. However, steady and systematic dissection over the last 20 years has revealed that this is not the case. Instead, the TCR repertoire deployed against individual antigens is routinely ordered and biased. Often, identical and near-identical TCR repertoires can be observed across different individuals, suggesting that the system encompasses an element of predictability. This review provides a catalog of αβ TCR bias by disease and by species, and discusses the mechanisms that govern this inherent and widespread phenomenon.

Regulatory and pro-inflammatory phenotypes of myelin basic protein-autoreactive T cells in multiple sclerosis

MBP-specific autoreactive T cells are considered pro-inflammatory T cells and thought to play an important role in the pathogenesis of multiple sclerosis (MS). Here, we report that MBP(83-99)-specific T cells generated from MS patients (n = 7) were comprised of pro-inflammatory and regulatory subsets of distinct phenotypes. The pro-inflammatory phenotype was characterized by high production of IFN-gamma, IL-6, IL-21 and IL-17 and low expression of FOXP3, whereas the regulatory subset expressed high levels of FOXP3 and exhibited potent regulatory functions. The regulatory subset of MBP-specific T cells appeared to expand from the CD4(+)CD25(-) T-cell pool. Their FOXP3 expression was stable, independent of the activation state and it correlated with suppressive function and inversely with the production of IFN-gamma, IL-6, IL-21 and IL-17. In contrast, the phenotype and function of FOXP3(low) MBP-specific T cells were adaptive and dependent on IL-6. The higher frequency of FOXP3(high) MBP-specific T cells was observed when IL-6 was neutralized in the culture of PBMC with MBP. The study provides new evidence that MBP-specific T cells are susceptible to pro-inflammatory cytokine milieu and act as either pro-inflammatory or regulatory T cells.

Inflammation on the mind: visualizing immunity in the central nervous system

The central nervous system (CNS) is a remarkably complex structure that utilizes electrochemical signaling to coordinate activities throughout the entire body. Because the nervous system contains nonreplicative cells, it is postulated that, through evolutionary pressures, this compartment has acquired specialized mechanisms to limit damage. One potential source of damage comes from our immune system, which has the capacity to survey the CNS and periphery for the presence of foreign material. The immune system is equipped with numerous effector mechanisms and can greatly alter the homeostasis and function of the CNS. Degeneration, autoimmunity, and pathogen infection can all result in acute, and sometimes chronic, inflammation within the CNS. Understanding the specialized functionality of innate and adaptive immune cells within the CNS is critical to the design of more efficacious treatments to mitigate CNS inflammatory conditions. Much of our knowledge of CNS-immune interactions stems from seminal studies that have used static and dynamic imaging approaches to visualize inflammatory cells responding to different CNS conditions. This review will focus on how imaging techniques have elevated our understanding of CNS inflammation as well as the exciting prospects that lie ahead as we begin to pursue investigation of the inflamed CNS in real time.

Evaluating human T cell receptor gene expression by PCR

This unit describes the use of PCR to characterize and quantify rearranged transcripts from specific T cell receptor variable gene families in human tissue and peripheral blood lymphocytes. The strategy outlined in this unit has been extensively used on different sources of human tissue including brain, spinal cord, and skeletal muscle. A protocol is provided to clone and sequence PCR-amplified cDNA transcripts to study the junctional diversity of the expressed genes. A support protocol describes a method for reverse transcribing total RNA to make the cDNA required by the other protocols.

Multiple sclerosis and virus induced immune responses: autoimmunity can be primed by molecular mimicry and augmented by bystander activation

Polymicrobial infections have been associated with plausible immune mediated diseases, including multiple sclerosis (MS). Virus infection can prime autoimmune T cells specific for central nervous system (CNS) antigens, if virus has molecular mimicry with CNS proteins. On the other hand, infection of irrelevant viruses will induce two types of cytokine responses. Infection with a virus such as lymphocytic choriomeningitis virus (LCMV), can induce interferon (IFN)-alpha/beta production and suppress autoimmunity, while infection with a virus, such as murine cytomegalovirus (MCMV), can activate natural killer (NK), NKT and dendritic cells, resulting in interleukin (IL)-12 and IFN-gamma production. These cytokines can cause bystander activation of autoreactive T cells. We established an animal model, where mice infected with vaccinia virus encoding myelin protein can mount autoimmune responses. However, the mice develop clinical disease only after irrelevant immune activation either with complete Freund's adjuvant or MCMV infection. In this review, we propose that a combination of two mechanisms, molecular mimicry and bystander activation, induced by virus infection, can lead to CNS demyelinating diseases, including MS. Viral proteins having molecular mimicry with self-proteins in the CNS can prime genetically susceptible individuals. Once this priming has occurred, an immunologic challenge could result in disease through bystander activation by cytokines.

Human TCR-binding affinity is governed by MHC class restriction

T cell recognition is initiated by the binding of TCRs to peptide-MHCs (pMHCs), the interaction being characterized by weak affinity and fast kinetics. Previously, only 16 natural TCR/pMHC interactions have been measured by surface plasmon resonance (SPR). Of these, 5 are murine class I, 5 are murine class II, and 6 are human class I-restricted responses. Therefore, a significant gap exists in our understanding of human TCR/pMHC binding due to the limited SPR data currently available for human class I responses and the absence of SPR data for human class II-restricted responses. We have produced a panel of soluble TCR molecules originating from human T cells that respond to naturally occurring disease epitopes and their cognate pMHCs. In this study, we compare the binding affinity and kinetics of eight class-I-specific TCRs (TCR-Is) to pMHC-I with six class-II-specific TCRs (TCR-IIs) to pMHC-II using SPR. Overall, there is a substantial difference in the TCR-binding equilibrium constants for pMHC-I and pMHC-II, which arises from significantly faster on-rates for TCRs binding to pMHC-I. In contrast, the off-rates for all human TCR/pMHC interactions fall within a narrow window regardless of class restriction, thereby providing experimental support for the notion that binding half-life is the principal kinetic feature controlling T cell activation.

Characterization of CD8+ T cell repertoire in identical twins discordant and concordant for multiple sclerosis

Autoreactive CD4+ and CD8+ T cells directed against CNS autoantigens may play a role in the development of multiple sclerosis (MS). Identical twins share the same genetic background but not the TCR repertoire that is shaped by the encounter with self or foreign antigens. To gain insights into the interplay between MS and T cell repertoire, peripheral blood CD4+ and CD8+ T lymphocytes and their CCR7+/CCR7- subsets from five pairs of identical twins (four discordant and one concordant for MS; none of which had taken disease-modifying therapy) were compared by TCR beta-chain (TCRB) complementary-determining region 3 (CDR3) spectratyping. CD4+ T cells generally showed a Gaussian distribution, whereas CD8+ T cells exhibited subject-specific, widely skewed TCR spectratypes. There was no correlation between CD8+ T cell oligoclonality and disease. Sequencing of predominant spectratype expansions revealed shared TCRB-CDR3 motifs when comparing inter- and/or intrapair twin members. In many cases, these sequences were homologous to published TCRs, specific for viruses implicated in MS pathogenesis, CNS autoantigens, or copaxone [glatiramer acetate (GA)], implying the occurrence of naturally GA-responding CD8+ T cells. It is notable that these expanded T cell clones with putative pathogenic or regulatory properties were present in the affected as well as in the healthy subject, thus suggesting the existence of a "MS predisposing trait" shared by co-twins discordant for MS.

Multiple sclerosis is linked to Epstein-Barr virus infection

The aetiology and pathogenesis of MS are unknown, but environmental agents, genetic susceptibility and stochastic events are likely to be involved. In order to evaluate the possibility that MS is linked to EBV infection, we here evaluate studies on MS- and EBV-epidemiology, prospective and retrospective analysis of EBV-serology, investigations of EBV DNA sequences in blood and tissues, specificity of antibodies in oligoclonal bands in MS patients and results from antiviral chemotherapy of MS patients. It could be demonstrated that EBV is complying with the epidemiological observations in MS and that all MS patients are seropositive to EBV in contrast to healthy controls. Importantly, despite difficulties in diagnosing child-MS, the vast majority of these patients are also EBV seropositive. In contrast to control groups, recent EBV infections have never been observed in children or adults with MS. Further prospective studies indicate a 2.8 times higher tendency for development of MS after infectious mononucleosis. In MS patients, unbiased analyses pull out EBV antigens as high-affinity targets for the antibodies in the oligoclonal bands. Humans are the exclusive natural host for EBV, a finding that may explain why MS is unique to humans. Together these unique observations strongly suggest a linkage between MS and EBV infection. Infection by EBV offers numerable mechanisms to perturb the immune system, including mimicry and superantigen induction, which may potentially participate in the disease mechanisms. In contrast, studies demonstrating higher IgG titres and occurrence of viral DNA in serum/plasma are likely to reflect a consequence of the disease. An explanation for a potential role of respiratory diseases in MS is discussed. It is concluded that the ultimate test to the hypothesis of MS and EBV is the development and application of an EBV vaccine, which is predicted to eradicate the disease.

Serial blood T cell repertoire alterations in multiple sclerosis patients; correlation with clinical and MRI parameters

A significant skewing of the peripheral T cell repertoire has been shown in relapsing-remitting multiple sclerosis (MS). Most of the studies already performed in this field are cross-sectional and therefore, little is known of the T cell repertoire evolution over time in MS and the correlation of T cell repertoire variation with clinical and MRI parameters. This study was performed on serially harvested frozen PBMC from nine untreated MS patients (27 samples) and 14 healthy individuals. The blood T cell repertoire of each patient was analysed at the complementarity determining region 3 (CDR3) level and compared with a monthly MRI scan performed over a six month period with assessment of T2 lesion load and gadolinium enhancing lesions. A highly significant blood T cell repertoire skewing was observed in MS patients as compared with healthy controls (p<0.01). In addition, the number of altered Vbeta families correlated significantly with both the T2 lesion volume and the number of gadolinium enhancing lesions as assessed by MRI (Spearman correlation tests, r=0.51 and r=0.44, p<0.01 and p<0.05 respectively). Furthermore, the variation of the number of altered Vbeta families over time also correlated with the appearance of new gadolinium enhancing lesions (r=0.36, p=0.05). These findings which need confirmation on larger serial cohorts, suggest an association between the magnitude of TCRBV CDR3 length distribution alterations in the peripheral blood of MS patients and the disease process.

Transgenic mice expressing the T cell antigen receptor specific for an immunodominant epitope of a major allergen of house dust mite develop an asthmatic phenotype on exposure of the airways to allergen

BACKGROUND

Current studies on mechanisms underlying allergen-induced pulmonary inflammation and asthma are hampered by the lack of appropriate physiological in vivo models that reflect the natural route of allergen exposure and sensitization.

OBJECTIVE

To generate and phenotype a transgenic mouse strain expressing the T cell receptor (TCR) specific for an immunodominant domain of the major inhalant allergen Dermatophagoides pteronyssinus species of house dust mite (Der p 1), for the development of an in vivo model of allergic asthma.

METHODS

Der p 1 transgenic mice were generated using TCR-alphabeta derived from a CD4+ T cell hybridoma reactive with Der p 1 residues p 110-131. The frequency and functional activity of peripheral T cells were determined and parameters of airway inflammation assessed following allergen challenge of the airways with Der p 1.

RESULTS

CD4+ T cells are functionally active, exhibiting dose-dependent proliferation and IL-4 production on primary stimulation with Der p 1 or Der p 1, p 110-131 in vitro, independent of in vivo antigen priming. On sensitization of the airways with allergen, in the absence of systemic priming or the application of adjuvants, the TCR transgenic mice develop airway inflammation characterized by a marked lymphocytic and eosinophilic infiltrate with goblet cell hyperplasia and enhanced mucin production.

CONCLUSION

The Der p 1 TCR transgenic mice provide a model for investigating the pathophysiological mechanisms of pulmonary inflammation following sensitization by exposure of the airways to allergen and for investigating the mode of action and efficacy of novel immunotherapeutics.

An improved methodology to detect human T cell receptor beta variable family gene expression patterns

Comprehensive gene expression analysis of the T cell receptor repertoire of an individual can be very useful in evaluating the immune response in a variety of conditions. Antibody-based analysis methods can detect approximately 60% of the human T cell receptor beta variable (TCRBV) proteins, while gene expression analysis, primarily through employment of the polymerase chain reaction (PCR), has had somewhat greater success in the detection of additional TCRBV families. Many of these previous PCR methods, however, have been unable to detect all 91 alleles of the human TCRBV genes. This is primarily due to either deficiencies in the amplification of all of the variable beta families, subfamilies, and alleles, or the prior lack of a systematic classification of the TCR variable family gene segment sequences. We describe here a real-time reverse transcription polymerase chain reaction-based method, which allows efficient automation and integration of amplification, detection, and analysis with sequence-specific detection of all T cell receptor beta variable gene families, subfamilies, and alleles. This method, which in itself contributes significant improvements over existing technologies through its comprehensiveness and efficiency, also functions independently of variables such as sample source and sample processing and has the ability to run on multiple real-time PCR platforms, affording one the implementation of personal preferences.

Immunology of multiple sclerosis

Multiple sclerosis (MS) develops in young adults with a complex predisposing genetic trait and probably requires an inciting environmental insult such as a viral infection to trigger the disease. The activation of CD4+ autoreactive T cells and their differentiation into a Th1 phenotype are a crucial events in the initial steps, and these cells are probably also important players in the long-term evolution of the disease. Damage of the target tissue, the central nervous system, is, however, most likely mediated by other components of the immune system, such as antibodies, complement, CD8+ T cells, and factors produced by innate immune cells. Perturbations in immunomodulatory networks that include Th2 cells, regulatory CD4+ T cells, NK cells, and others may in part be responsible for the relapsing-remitting or chronic progressive nature of the disease. However, an important paradigmatic shift in the study of MS has occurred in the past decade. It is now clear that MS is not just a disease of the immune system, but that factors contributed by the central nervous system are equally important and must be considered in the future.

Analysis of T-cell receptor V beta gene repertoires after immune stimulation and in malignancy by use of padlock probes and microarrays

BACKGROUND

Detection of expanded T-cell clones, identified by their receptor (TCR) repertoires, can assist diagnosis and guide therapy in infectious, inflammatory, and autoimmune conditions as well as in tumor immunotherapy. Analysis of tumor-infiltrating lymphocytes often reveals preferential use of one or a few TCR V beta genes, compared with peripheral blood, indicative of a clonal response against tumor antigens.

METHODS

To simultaneously measure the relative expression of all V beta gene families, we combined highly specific and sensitive oligonucleotide reagents, called padlock probes, with a microarray read-out format. T-Cell cDNA was combined with a pool of V beta subfamily-specific padlock probes. Reacted probes were selectively amplified and the products hybridized to a microarray, from which the V beta subfamily distribution in each sample could be determined relative to a control sample.

RESULTS

In lymphocytes stimulated with the superantigen staphylococcal enterotoxin B, we detected expansions at the mRNA level of TCR subfamilies previously shown to respond to staphylococcal enterotoxin B. Expansions of the same V beta families could also be detected by flow cytometry. In samples from two bladder cancer patients, we detected predominant representations of specific V beta subfamilies in both tumor-infiltrating lymphocytes and in the draining lymph nodes, but not in non-tumor-draining lymph nodes or peripheral blood. Several expression profiles from draining lymph nodes in patients with malignant melanoma were divergent from profiles seen in non-tumor-draining lymph nodes.

CONCLUSION

Padlock probe-based parallel analysis of TCR V beta gene distributions provides an efficient method for screening multiple samples for T-cell clonal expansions with reduced labor and time of analysis compared with traditional methods.

Ex vivo expansion of CD8+CD56+ and CD8+CD56- natural killer T cells specific for MUC1 mucin

Prostate cancers express MUC1, but nearly all metastatic cells lack HLA class I molecules. Thus, a lymphocyte population that can sense its antigenic environment, while also able to react to stimuli of natural killer (NK) cells, may be a more versatile effector cell population for antitumor immune responses. Herein, we report that tumor-specific MUC1 peptide, interleukin 2, and interleukin 12 act synergistically to stimulate the ex vivo expansion of CD8(+)CD56(-) T cells and CD8(+)CD56(+) natural killer T (NKT) cells from the peripheral blood mononuclear cells of prostate cancer patients, as well as healthy male and female donors. Both the CD56(+) NKT cells and CD56(-) T cells lysed allogeneic mucin-bearing target cells, as well as NK target cells, but not lymphokine-activated killer target cells. However, the CD56(+) NKT cells displayed a 2-fold greater cytolytic activity than the CD56(-) T cells. The mucin-specific cytolytic activity and NK cytolytic activities for both lymphocyte populations were independent of HLA class I and CD1 molecules. The CD56(-) T cells up-regulated CD56 with continued antigenic stimulation in the presence of interleukin 12, suggesting that CD8(+)CD56(-) T cells are NKT cells. However, CD56(+) NKT cells expand poorly to continued stimulation. All mucin-stimulated NKT cells exhibited the activated/memory CD45RO phenotype. The NKT cell lines express the alpha/beta T-cell receptor (TCR). The TCR repertoire was limited and varied with cell line, but was not the V alpha 24V beta 11 TCR typically associated with NKT cells. Whereas CD161 is generally considered a marker of NKT cells, the mucin-stimulated NKT cells did not express this marker. Thus, we have described two phenotypically distinct NKT types that do not display a biased TCR repertoire, but do display specificity for a tumor-specific peptide antigen (CTL-like activity), as well as HLA class I-deficient target cells (NK-like activity).

The same TCR (N)Dβ(N)Jβ junctional region is associated with several different vβ13 subtypes in a multiple sclerosis patient at the onset of the disease

In multiple sclerosis (MS), the T-cell receptors (TCRS) of autoreactive T lymphocytes recognize various myelin components or derivatives including peptides of the myelin basic protein (MBP). Using the exhaustive immunoscope approach we showed that the T-cell repertoires of MS patients differ from those of healthy controls, with expansion of Vbeta13 cell clones in cerebrospinal fluid (CSF) and in peripheral blood lymphocytes (PBLs). Sequencing of the beta13(+) chains of T cells recovered from the CSF revealed high interindividual diversity, and no particular Vbeta13(+) rearrangements were shown to be myelin-autoreactive. Within the overall Vbeta13 repertoire in the CSF of patient MS3 at the onset of the disease, most of the overrepresented (N)Dbeta(N)Jbeta junctional regions were found to be associated with two or three different Vbeta13 segments. These rearrangements were most common in the PBLs of patient MS3. No such associations were detected in the Vbeta5 multigene family that was used as a control. Thus, Vbeta13 T cells infiltrating the CSF from patient MS3 may have been selected on the basis of both the Vbeta13 segments and the (N)Dbeta(N)Jbeta junctional CDR3 sequence.

CDR3 spectratyping analysis of the T cell receptor repertoire in Guillain-Barré and Fisher syndromes

Several autoimmune and infectious disorders show oligoclonal expansion of particular T cell phenotypes. The extent of T cell involvement in the pathogenesis of Guillain-Barré syndrome (GBS), a post-infectious autoimmune neuropathy, however, is not clear. To identify the pathogenic T cell phenotypes in GBS and Fisher syndrome (FS), variations in T cell receptor use of the V beta 1-24 and V delta 1-5 chain genes were analyzed at complementarity-determining region 3 level in 119 patients with GBS or FS. Overall, V beta and V delta spectratypes were expanded more frequently in patients with GBS (V beta in 77%, V delta in 53%) or FS (V beta in 75%, V delta in 65%) than in the healthy controls (V beta in 59%, V delta in 38%). No particular spectratype was significantly associated with GBS or FS. Subgrouping the patients by Campylobacter jejuni serology and anti-ganglioside IgG antibodies also failed to detect particular spectratype gene use. The frequency of V beta 5.2 expansion tended to be higher in patients with positive Haemophilus influenzae serology (50%) than in the controls (7%), but the difference was not significant. Our findings show that oligoclonal expansion of T cells bearing particular type T cell receptor V beta and V delta genes frequently occurs in GBS and FS, suggestive that T cells mediate the development of these neuropathies. The predominant phenotypes vary, even within subgroups of patients with a syndrome of single etiological origin or those with uniform serological features.

Complementarity-determining region 3 spectratyping analysis of the TCR repertoire in multiple sclerosis

Multiple sclerosis (MS) is considered to be an autoimmune disease mediated by T cells reactive with Ags in the CNS. Therefore, it has been postulated that neuroantigen-reactive T cells bearing particular types of TCRs are expanded clonally during the course of the disease. However, there is a controversy with regard to the TCR usage by T cells associated with the development of MS. By the use of complementarity-determining region 3 spectratyping analysis that is shown to be a useful tool for identification of pathogenic TCR in autoimmune disease models, we tried to demonstrate that spectratype was T cells bearing particular types of TCR are activated in MS patients. Consequently, it was found that Vbeta5.2 were often oligoclonally expanded in peripheral blood of MS patients, but not of healthy subjects. Sequence analysis of the complementarity-determining region 3 region of spectratype-derived TCR clones revealed that the predominant TCR clone was different from patient to patient, but that similar results were obtained in a patient examined at different time points. More importantly, examination of cerebrospinal fluid T cells and longitudinal studies of PBLs from selected patients revealed that Vbeta5.2 expansion was detectable in the majority of patients examined. These findings suggest that Vbeta5.2 spectratype expansion is associated with the development of MS and that TCR-based immunotherapy can be applicable to MS patients if the TCR activation pattern of each patient is determined at different stages of the disease.

Cross-reactivity with myelin basic protein and human herpesvirus-6 in multiple sclerosis

Viral infections are though to play an important role in the pathogenesis of multiple sclerosis (MS) potentially through molecular mimicry. An identical sequence was found in both myelin basic protein (MBP, residues 96-102), a candidate autoantigen for MS, and human herpesvirus-6 (HHV-6 U24, residues 4-10) that is a suspected viral agent associated with MS. In this study, we showed that greater than 50% of T cells recognizing MBP(93-105) cross-reacted with and could be activated by a synthetic peptide corresponding to residues 1 to 13 of HHV-6 U24 in MS patients. The estimated precursor frequency of these cross-reactive T cells recognizing both peptides, MBP(93-105) and HHV-6 (U24)(1-13), was significantly elevated in MS patients compared with that in healthy controls. These cross-reactive CD4+ T cells represented the same Th1 phenotype as that of monospecific T cells recognizing MBP(93-105). There were increased antibody titers for both peptide HHV-6 (U24)(1-13) and peptide MBP(93-105) in the same patients with MS compared with those in healthy controls, suggesting B-cell sensitization to the antigens in MS patients. The study provides important evidence in the understanding of the potential role of HHV-6 infection/reactivation in the activation of autoimmune reactivity to MBP and its implication in the pathogenesis of MS.

T-cell-receptor gene usage of Actinobacillus actinomycetemcomitans-reactive periodontal CD4+ T cells from localized juvenile periodontitis patients and human peripheral blood leukocyte-reconstituted NOD/SCID mice

We investigated the variable Valpha and Vbeta gene usage of Actinobacillus actinomycetemcomitans-reactive periodontal CD4+ T cell receptors (TCR) from: (i) four A. actinomycetemcomitans-infected localized juvenile periodontitis (LJP) patients, (ii) four groups of A. actinomycetemcomitans-inoculated NOD/SCID mice engrafted with individual LJP-derived HuPBL and (iii) HuPBL samples of four LJP patients and two healthy control subjects, by quantitative PCR analyses. The results show that: (i) the majority of the TCR genes (82.5% of Valpha and 91.1% of Vbeta) used by periodontal CD4+ T cells in A. actinomycetemcomitans-inoculated HuPBL-engrafted NOD/SCID mice overlap with those used by local periodontal T cells in LJP patients, (ii) although A. actinomycetemcomitans-reactive periodontal CD4+ TCR repertoire is relatively widespread, there are a few dominant genes shared by the LJP patients, suggesting a limited number of antigens or epitopes commonly recognized and (iii) A. actinomycetemcomitans likely lacks superantigenic characteristics. These results suggest A. actinomycetemcomitans-associated human CD4+ T cell repertoire established in HuPBL-NOD/SCID mice provides a useful approach to study specific aspects of immune-parasite interactions in the periodontium.

Simultaneous analysis of T cell clonality and cytokine production in rheumatoid arthritis using three-colour flow cytometry

In this study we examined the cytokine production by T cells and TCRVbeta subsets in peripheral blood (PB) and synovial fluid (SF) from six RA patients and PB from 10 normal subjects, using three-colour flow cytometry. In two RA subjects we assessed T cell clonality by RT PCR using TCRBV family-specific primers and analysed the CDR3 (complementarity determining region 3) length by GeneScan analysis. A high percentage of IFN-gamma- and IL-2- producing cells was observed among the PB T cells in both the RA patients and normal controls and among the SF T cells in RA patients. In contrast, the percentage of T cells producing IL-4 and IL-5 was small among PB T cells in both RA patients and normal controls and among SF T cells in RA patients. There was no significant difference in the production of IFN-gamma, IL-2 and IL-5 between the two compartments (PB and SF); however, there were significantly more IL-4-producing cells in SF. Molecular analysis revealed clonal expansions of four TCRBV families in SF of two of the RA patients studied: TCRBV6.7, TCRBV13.1 and TCRBV22 in one and TCRBV6.7, TCRBV21.3 and TCRBV22 in the second. These expansions demonstrated cytokine expression profiles that differed from total CD3+ cells, implying that T cell subsets bearing various TCR-Vbeta families may have the potential to modulate the immune response in RA patients.

Conserved CDR 3 region of T cell receptor BV gene in lymphocytes from bronchoalveolar lavage fluid of patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an inflammatory lung disease characterized by the accumulation of inflammatory cells and deposition of collagen, resulting in lung remodelling. High numbers of T cells are present in bronchoalveolar lavage fluid (BALF) of IPF patients, although the characteristics of these cells are yet to be determined. To elucidate the pathogenic mechanisms of IPF, we analysed the T cell receptor (TCR) of BALF lymphocytes in three patients with IPF and three healthy subjects as control. TCR repertoire of BALF lymphocytes and T cell clonality were examined by family PCR and Southern blot analysis, and single-strand conformation polymorphism (SSCP), respectively. We observed that the TCR repertoire in the lung was heterogeneous, both in the control subjects and three patients with IPF. SSCP analysis demonstrated an increase in the number of accumulated T cell clones in BALF of two of the three patients, but not in the healthy subject. Furthermore, junctional sequence analysis showed the presence of conserved amino acid motifs (ETGRSG, LAxG, QGQ, GxQP, GRxG, VAR, PGT, GTI, GGT, TGR, LxLxQ, SGQ) in the TCR-CDR 3 region of BAL lymphocytes in patients with IPF, whereas only two amino acid motifs (VTTG, GGE) were found in the control. Our findings suggest that T cells in BALF of patients with IPF expand oligoclonally in the lung, suggesting antigen stimulation of these cells.

T-cell clonotypes specific for Dermatophagoides pteronyssinus in the skin lesions of patients with atopic dermatitis

T-cell mediated immune response, toward the house dust mite (HDM) antigens in particular, has been reported to be involved in the pathogenesis of atopic dermatitis (AD). On the other hand, studies on the infiltrating lymphocytes in the skin lesion of AD revealed oligoclonal T-cell accumulation. However, it is not clear exactly what antigen(s) the accumulating T cells are exactly recognize in situ. Therefore, this study attempted to determine whether or not the clonally expanded T-cell clones in the diseased skin recognize HDM. Specifically, peripheral blood mononuclear cells (PBMC) obtained from six patients with AD, who revealed high titers of anti-HDM IgE, were stimulated with HDM antigens purified from Dermatophagoides pteronyssinus (Dp). T-cell clonotypes expanded by the stimulation were then identified by the analysis of their T-cell receptor (TCR) B-gene sequences using a combination of the reverse transcription-polymerase chain reaction and subsequent single strand conformation polymorphism separation. The Dp-responding T-cell clonotypes were compared with those that accumulated in the AD skin lesion in vivo. Nucleotide sequences of the TCR were also determined. As a result, the Dp stimulation induced oligoclonal T-cell expansion from the originally heterogeneous peripheral T-cell population of AD patients. However, only a small part of the Dp-reacting T-cell clonotypes detected in PBMC was identical to those accumulated in the AD skin lesion in vivo, and vice versa. This indicates that the frequency of the clonal expansion of Dp-specific T-cell clonotypes in the skin lesion of AD would be rather limited.

Short-term dynamics of circulating T cell receptor V beta repertoire in relapsing-remitting MS

To understand the short-term dynamics of the circulating T cell receptor V beta (TCRBV) repertoire in relapsing-remitting multiple sclerosis (MS), we monitored the TCRBV profiles of untreated MS patients and healthy controls. Expansions of TCRBV genes in MS patients were significantly more frequent than in controls (P<0.001), were predominantly oligoclonal (80%) and were significantly correlated with immune responses to myelin basic protein (MBP) (P<0.02) and with inflammatory disease activity detected by magnetic resonance imaging (MRI) (P<0.05). Autoreactive T cell responses against myelin antigens may be implicated in perturbations of TCR repertoire in untreated MS patients, detectable even in the absence of clinically evident manifestations.

T-cell receptor bias in patients with allergic bronchopulmonary aspergillosis

CD4(+) Th2 helper cell mediated immune responses have been shown to play a crucial role in the pathogenesis of ABPA. HLA and TCR are the candidate genes, which can influence the specificity of these responses. We have previously established a strong association of HLA DR2/5 in ABPA susceptibility. The study was designed to determine whether allergen specific T cell express a limited usage of T cell receptor (TCR) Vbeta gene repertoire in ABPA and to find an association of susceptible HLA-DR determinants with the identified TCR gene segments. TCR Vbeta typing was performed on antigen specific T cell lines from 14 ABPA and 12 nonABPA patients. The majority of ABPA patients (86%) expressed allergen specific T cells with Vbeta13 genes indicating its role in susceptibility, whereas in nonABPA controls, Vbeta1 genes T cell repertoires were predominantly expressed. The unrestricted pattern of Vbeta gene amplification seen before antigen stimulation suggests an oligoclonal expansion of a specific T cell population in response to the allergen Asp f 1 in ABPA and nonABPA patients. The increased usage of Vbeta13 in ABPA and Vbeta1 in nonABPA indicates their importance in susceptibility and resistance, respectively.

Restricted T-cell receptor beta-chain usage by T cells autoreactive to beta(2)-glycoprotein I in patients with antiphospholipid syndrome

We recently identified CD4(+) T cells that are autoreactive to beta(2)-glycoprotein I (beta(2)GPI) and that promote antiphospholipid antibody production in patients with antiphospholipid syndrome (APS). In this study, T-cell receptor (TCR) beta chains of beta(2)GPI-reactive T cells were examined in 8 beta(2)GPI-responders, including 5 patients with APS and 3 healthy subjects, using polymerase chain reaction and single-strand conformation polymorphism (PCR-SSCP) analysis combined with in vitro stimulation of peripheral blood T cells with recombinant beta(2)GPI. The TCR Vbeta segments that expanded oligoclonally after stimulation with beta(2)GPI varied among responders, but the Vbeta7 and Vbeta8 segments were commonly detected in 6 and 4 beta(2)GPI-responders, respectively. Analysis of the complementarity-determining region 3 sequence of beta(2)GPI-reactive T cells revealed limited diversity, and all Vbeta7(+) TCRs had an amino acid motif of TGxxN/Q or minor variations. The Vbeta8(+) TCRs had another motif, PxAxxD/E. Surprisingly, an identical Vbeta7(+) TCRbeta chain was used by beta(2)GPI-reactive T cells in 3 patients with APS. There was no apparent difference in the TCRbeta usage between APS patients and healthy responders. Some of the Vbeta7(+) TCRs with the TGxxN/Q motif detected by PCR-SSCP analysis were also used by beta(2)GPI-specific CD4(+) T-cell clones responsive to an immunodominant epitope containing the major phospholipid-binding site. Depletion of Vbeta7(+) or Vbeta8(+) T cells from the peripheral blood mononuclear cell cultures significantly inhibited in vitro anti-beta(2)GPI antibody production in response to beta(2)GPI. Our results indicate preferential usage of TCRbeta chains by beta(2)GPI-reactive T cells. These TCRbeta chains can be reasonable targets for TCR-based immunotherapy for patients with APS.

CD4 positive peripheral T cells from patients with systemic lupus erythematosus (SLE) are clonally expanded

T cell activation was analysed in peripheral CD4+ T cells from both systemic lupus erythematosus (SLE) patients with active and inactive disease as well as in normal healthy donors (NHD) to investigate the involvement of CD4+ T cells in the etiopathogenesis of SLE. CD4+ T cell receptor (TCR) beta-chain transcripts, containing the complementarity determining region 3 (CDR3), were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) and analysed by high-resolution polyacrylamide gel electrophoresis. In addition the CDR3 of both clonally activated as well as heterogeneous Vbeta families from SLE patients were analysed at the molecular level. We observed a restricted CDR3 length polymorphism in peripheral CD4+ T cells from SLE patients compared with NHD, more pronounced in patients with high disease activity. Furthermore, in some Vbeta families single peaks in the histogram indicated nearly monoclonal T cell expansion. Sequencing of selected TCR beta-chains revealed a increased content of acidic amino acids in the CDR3 encoded by either proximal Jbeta elements or N nucleotides. We conclude that CD4+ T cells from peripheral blood of SLE patients display features of a secondary antigen driven immune response. The bias of the CDR3 towards acidic amino acids suggests the involvement of positively charged antigens.

Diminished frequency of interleukin-10-secreting, T-cell receptor peptide-reactive T cells in multiple sclerosis patients might allow expansion of activated memory T cells bearing the cognate BV gene

T cells responsive to T-cell receptor (TCR) determinants may regulate pathogenic Th1 responses in patients with multiple sclerosis (MS) through interleukin (IL)-10-dependent bystander suppression. In this study, innate IL-10- and interferon (IFN)-gamma-secreting T cells responsive to TCR peptides were quantified in peripheral blood mononuclear cells of MS patients and healthy controls (HC) using the ELISPOT assay. Most HC had vigorous IL-10 but low IFN-gamma frequencies to BV5S2 and BV6S1 peptides. In contrast, MS patients had significantly lower IL-10 frequency responses to the TCR peptides but normal responses to concanavalin A. Patients undergoing TCR-peptide vaccination had moderate responses that fluctuated in concert with vaccination. In an MS patient and HC, expression of BV6S1 by activated memory T cells was inversely associated with the presence of IL-10-secreting BV6S1-reactive T cells. These results suggest that MS patients have diminished frequencies of innate TCR-reactive T cells that may allow oligoclonal expansion of activated autoreactive Th1 effector cells expressing cognate V genes.

Structural analysis of TCRalpha and beta chains from human T-Cell clones specific for small nuclear ribonucleoprotein polypeptides Sm-D, Sm-B and U1-70 kDa: TCR complementarity determining region 3 usage appears highly conserved

Systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) are systemic autoimmune diseases that are characterized by the presence of autoantibodies reactive with U small nuclear RNP (snRNP) autoantigens. Both B and T cells are important in the pathogenesis of the disease, and T- and B-cell immunity against snRNP polypeptides have been shown to be linked in vivo. Currently, several alternative hypotheses for the pathogenesis of these diseases have been proposed. These include loss of tolerance, modified self-antigens, molecular mimicry and nondirected immune activation. To help distinguish between the various models of disease pathogenesis, we have characterized the T-cell receptor (TCR) CDR3 from a large panel of well-characterized human T-cell clones and lines specific for individual snRNP polypeptides. The results presented here reveal highly restricted TCR usage across patients by the snRNP-reactive T cells based on the deduced amino acid sequence of the CDR3 loop. These data support the hypothesis that T-cell responses against self antigens in SLE and MCTD are antigen driven and that there are a limited number of T-cell epitopes present on the snRNP autoantigens.

Characterization of T cell receptor (TCR) of organ-specific autoimmune disease-inducing T cells and TCR-based immunotherapy with DNA vaccines

Organ-specific autoimmune diseases and their animal models are characterized by the finding that the development of the diseases is closely associated with, or induced by, T cells reactive to organ-specific antigens. Therefore, the identification of T cell receptors (TCR) used by disease-inducing T cells within a short period of time is a key factor for designing TCR-based immunotherapy. The findings introduced in this article show that TCR associated with the development of multiple sclerosis and experimental autoimmune diseases including encephalomyelitis (EAE), neuritis (EAN) and carditis (EAC) are identifiable by complementarity-determining region 3 (CDR3) spectratyping analysis and subsequent sequencing of the CDR3 region of spectratype-derived TCR clones. It is also demonstrated that immunotherapy targeting disease-associated TCR using monoclonal antibodies and DNA vaccines significantly reduced the histological severity, and completely suppressed the inflammation in some animals. Since depletion or suppression of one of several types of effector cells does not significantly improve the severity of the disease, combined TCR-based immunotherapy should be considered as a primary therapy for T cell-mediated autoimmune diseases. TCR-based immunotherapy after rapid identification of autoimmune disease-associated TCR by CDR3 spectratyping can be applicable, not only to animal, but also to human autoimmune diseases whose pathomechanism is poorly understood.