Expansion of a recurrent V beta 5.3+ T-cell population in newly diagnosed and untreated HLA-DR2 multiple sclerosis patients

Immunomodulatory and anti-inflammatory effects of probiotics in multiple sclerosis: a systematic review

Multiple sclerosis (MS) is an inflammatory and autoimmune neurological disorder which leads to demyelination. Although the etiology of MS is yet to be known, it appears that regulating the immune system and suppressing inflammatory pathways may possibly have a favorable effect on the healing of this disease. Evidence suggests that probiotics consumption via gut microbiome alteration devises beneficial effects in improving immune and inflammatory responses in MS. All articles were systematically searched (in the main databases) for this paper. Two investigators independently scrutinized full texts of the potentially eligible articles. The quality of the study was evaluated using standardized tools. The methodological quality of seven studies included in this review ranged from fair to good. The findings illustrated that there were statistically significant improvements in the static and dynamic balance in patients and animals with MS. In the paper in hand, the effects of probiotics administration on immune and inflammatory markers in MS disease are evaluated. In addition, the limitations and knowledge gaps were reported while proposing a possible mechanism of probiotics therapy in modulating immune and inflammatory responses. This systematic review indicated that the probiotics could improve immune and inflammatory parameters, the cytokines and cells in MS disease. Probiotics may have efficient effects in management and treatment of MS. More studies are required to clarify the effect of supplementation with probiotics and their mechanisms in MS disease.

Expanded CD8 T-cell sharing between periphery and CNS in multiple sclerosis

Objective

In multiple sclerosis (MS), central nervous system (CNS), cerebrospinal fluid (CSF), and blood display TCR clonal expansions of CD8⁺ T cells. These clones have been assumed – but never demonstrated – to be similar in the three compartments. Addressing this key question is essential to infer the implication of peripheral clonally expanded CD8⁺ T cells in the disease.

Methods

For the first time, TCR Vβ repertoire from paired blood (purified CD8⁺ and CD4⁺ T cells), CSF and CNS (22 lesions, various inflammatory and demyelination statuses) samples from three MS patients was studied using complementary determining region 3 (CDR3) spectratyping and high-throughput sequencing. In parallel, blood and CNS clonally expanded CD8⁺ T cells were characterized by fluorescent staining.

Results

TCR Vβ repertoire analysis revealed strong sharing of predominant T-cell clones between CNS lesions, CSF, and blood CD8⁺ T cells. In parallel, we showed that blood oligoclonal CD8⁺ T cells exhibit characteristics of pathogenic cells, as they displayed a bias toward a memory phenotype in MS patients, with increased expression of CCR5, CD11a and Granzyme B (GZM-B) compared to non oligoclonal counterparts. CNS-infiltrating T cells were mainly CD8 expressing CD11a and GZM-B.

Interpretation

This study highlights the predominant implication of CD8⁺ T cells in MS pathophysiology and demonstrates that potentially aggressive CD8⁺ T cells can be easily identified and characterized from blood and CSF samples.

A novel method for analysis of human T cell repertoires by real-time PCR

T lymphocyte responses to challenges with multiple pathogens depend on the diversity of their T cell receptors (TcRs) that are heteroduplexes of alpha and beta chains. The regions of alpha and beta chains that define TcR specificity are encoded by rearranged variable (V) and joining (J) genes that are separated by variable numbers of nucleotides that encode the complementarity determining region 3 (CDR3). The assumption that a "healthy" T cell compartment exhibits broad TcR and CDR3 diversity has driven development of methods to evaluate diversity of TcR beta transcripts expressed by T lymphocyte populations and subpopulations in inflammatory sites and human malignancies. To that end, we have developed the BV:BJ matrix assay that uniquely generates a single statistic that describes TcR repertoire diversity and improves identification of beta transcripts expressed by expanded T cell clonotypes. The BV:BJ matrix uses rigorously selected primers specific for individual V and J genes to amplify beta transcripts in real-time PCRs driven by 533 BV:BJ primer pairs. The quantitative control of real-time PCRs produces Shannon entropy estimates of diversity that are reproducible over a range of template amounts and amenable to statistical analyses that have been difficult to perform with existing methods of repertoire analysis.

The past, present, and future of immune repertoire biology - the rise of next-generation repertoire analysis

T and B cell repertoires are collections of lymphocytes, each characterized by its antigen-specific receptor. We review here classical technologies and analysis strategies developed to assess immunoglobulin (IG) and T cell receptor (TR) repertoire diversity, and describe recent advances in the field. First, we describe the broad range of available methodological tools developed in the past decades, each of which answering different questions and showing complementarity for progressive identification of the level of repertoire alterations: global overview of the diversity by flow cytometry, IG repertoire descriptions at the protein level for the identification of IG reactivities, IG/TR CDR3 spectratyping strategies, and related molecular quantification or dynamics of T/B cell differentiation. Additionally, we introduce the recent technological advances in molecular biology tools allowing deeper analysis of IG/TR diversity by next-generation sequencing (NGS), offering systematic and comprehensive sequencing of IG/TR transcripts in a short amount of time. NGS provides several angles of analysis such as clonotype frequency, CDR3 diversity, CDR3 sequence analysis, V allele identification with a quantitative dimension, therefore requiring high-throughput analysis tools development. In this line, we discuss the recent efforts made for nomenclature standardization and ontology development. We then present the variety of available statistical analysis and modeling approaches developed with regards to the various levels of diversity analysis, and reveal the increasing sophistication of those modeling approaches. To conclude, we provide some examples of recent mathematical modeling strategies and perspectives that illustrate the active rise of a "next-generation" of repertoire analysis.

Clonal composition of neuroantigen-specific CD8+ and CD4+ T-cells in multiple sclerosis

Patients with multiple sclerosis (MS) show a high prevalence of myelin-reactive CD8+ and CD4+ T-cell responses, which are the putative effectors/modulators of CNS neuropathology. Utilizing a novel combination of short-term culture, CFSE-based sorting and anchored PCR, we evaluated clonal compositions of neuroantigen-targeting T-cells from RRMS patients and controls. CDR3 region analysis of TCRβ chains revealed biased use of specific TCRBV-bearing CD4+ clones. CD8+ clones showed homology to published TCR from CNS-infiltrating T-cells in MS lesions. These studies are the first description of TCR usage of CNS-specific CD8+ T-cells and provide insights into their potential regulatory role in disease.

Drug reaction with eosinophilia and systemic symptoms (DRESS): a multiorgan antiviral T cell response

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe, drug-induced reaction that involves both the skin and the viscera. Evidence for reactivation of herpes family viruses has been seen in some DRESS patients. To understand the immunological components of DRESS and their relationship to viral reactivation, we prospectively assessed 40 patients exhibiting DRESS in response to carbamazepine, allopurinol, or sulfamethoxazole. Peripheral blood T lymphocytes from the patients were evaluated for phenotype, cytokine secretion, and repertoire of CD4+ and CD8+ and for viral reactivation. We found Epstein-Barr virus (EBV), human herpes virus 6 (HHV-6), or HHV-7 reactivation in 76% of the patients. In all patients, circulating CD8+ T lymphocytes were activated, exhibited increased cutaneous homing markers, and secreted large amounts of tumor necrosis factor-alpha and interferon-gamma. The production of these cytokines was particularly high in patients with the most severe visceral involvement. In addition, expanded populations of CD8+ T lymphocytes sharing the same T cell receptor repertoire were detected in the blood, skin, liver, and lungs of patients. Nearly half of these expanded blood CD8+ T lymphocytes specifically recognized one of several EBV epitopes. Finally, we found that the culprit drugs triggered the production of EBV in patients' EBV-transformed B lymphocytes. Thus, cutaneous and visceral symptoms of DRESS are mediated by activated CD8+ T lymphocytes, which are largely directed against herpes viruses such as EBV.

Memory CD4 T-cell subsets discriminated by CD43 expression level in A-bomb survivors

PURPOSE

Our previous study showed that radiation exposure reduced the diversity of repertoires of memory thymus-derived cells (T cells) with cluster of differentiation (CD)- 4 among atomic-bomb (A-bomb) survivors. To evaluate the maintenance of T-cell memory within A-bomb survivors 60 years after radiation exposure, we examined functionally distinct memory CD4 T-cell subsets in the peripheral blood lymphocytes of the survivors.

METHODS

Three functionally different subsets of memory CD4 T cells were identified by differential CD43 expression levels and measured using flow cytometry. These subsets consist of functionally mature memory cells, cells weakly responsive to antigenic stimulation, and those cells functionally anergic and prone to spontaneous apoptosis.

RESULTS

The percentages of these subsets within the peripheral blood CD4 T-cell pool all significantly increased with age. Percentages of functionally weak and anergic subsets were also found to increase with radiation dose, fitting to a log linear model. Within the memory CD4 T-cell pool, however, there was an inverse association between radiation dose and the percentage of functionally mature memory cells.

CONCLUSION

These results suggest that the steady state of T cell memory, which is regulated by cell activation and/or cell survival processes in subsets, may have been perturbed by prior radiation exposure among A-bomb survivors.

The application of real-time PCR to the analysis of T cell repertoires

The diversity of T-cell populations is determined by the spectrum of antigen-specific T-cell receptors (TCRs) that are heterodimers of alpha and beta subunits encoded by rearranged combinations of variable (AV and BV), joining (AJ and BJ), and constant region genes (AC and BC). We have developed a novel approach for analysis of beta transcript diversity in mice with a real-time PCR-based method that uses a matrix of BV- and BJ-specific primers to amplify 240 distinct BV-BJ combinations. Defined endpoints (Ct values) and dissociation curves are generated for each BV-BJ combination and the Ct values are consolidated in a matrix that characterizes the beta transcript diversity of each RNA sample. Relative diversities of BV-BJ combinations in individual RNA samples are further described by estimates of scaled entropy. A skin allograft system was used to demonstrate that dissection of repertoires into 240 BV-BJ combinations increases efficiency of identifying and sequencing beta transcripts that are overrepresented at inflammatory sites. These BV-BJ matrices should generate greater investigation in laboratory and clinical settings due to increased throughput, resolution and identification of overrepresented TCR transcripts.

The IgE repertoire in PBMCs of atopic patients is characterized by individual rearrangements without variable region of the heavy immunoglobulin chain bias

BACKGROUND

Patients with atopic diseases are characterized by high levels of specific IgE production. However, little is known about the composition of their B-cell repertoires.

OBJECTIVES

We sought to analyze the complete PBMC-derived IgE repertoire and to compare clonal expansions between different patients.

METHODS

We have analyzed the IgE-bearing B-cell receptor repertoire in highly atopic patients (>1000 IU/mL) using quantitative RT-PCR, complementarity determining region 3 spectratyping, and sequence analysis. Three representative patients were additionally followed during anti-IgE therapy.

RESULTS

Atopic patients exhibited 100 to 1000 times more IgE-specific transcripts than control individuals. These patients used a variable region of the heavy immunoglobulin chain (VH) epsilon repertoire highly similar to their IgM and IgG repertoires, with preference of VH3b, VH4, VH3a, and VH1 segments. Each patient harbored individual clonal expansions, most probably as correlation of allergen-specific IgE production. Common expansions within the complementary determining region 3 shared by several individuals with similar sensitization patterns were found in spectratyping analysis. However, these antigen-driven expansions showed differences on the sequence level. In omalizumab-treated patients the clinical improvement was paralleled by a clear increase in the ratio of IgG/IgE transcripts.

CONCLUSION

The IgE repertoire in atopic patients follows the VH use patterns seen for other immunoglobulins and seems to preferentially recruit individual rearrangements rather than public expansions.

CLINICAL IMPLICATIONS

The detailed analysis of the IgE B-cell repertoire is highly suitable to follow changes in IgE uses during different therapy modalities.

The role of CD4 T cells in the pathogenesis of multiple sclerosis

T lymphocytes play a central role in the pathogenesis of multiple sclerosis (MS) (Zhang et al., 1992). Both CD4+ and CD8+ T cells have been demonstrated in MS lesions, with CD4+ T cells predominating in acute lesions and CD8+ T cells being observed more frequently in chronic lesions (Raine, 1994). Additionally, T cells are found in all four of the described histopathologic subtypes of MS (Lucchinetti et al., 2000). Activated myelin-reactive CD4+ T cells are present in the blood and cerebrospinal fluid (CSF) of MS patients; in contrast, only nonactivated myelin-reactive T cells are present in the blood of controls (Zhang et al., 1994). The success of several T-cell-targeted therapies in MS reinforces the importance of the role of the T cell in MS pathogenesis. Here, we outline basic concepts in CD4+ T-cell immunology and summarize the current understanding of the role of CD4+ T cells in the pathogenesis of MS.

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.

The DR4-DQ8 haplotype and a specific T cell receptor Vbeta T cell subset are associated with absence of allergy to Can f 1

BACKGROUND

The significance of specific T cell receptor (TCR) Vbeta subtypes and human leucocyte antigen (HLA) class II alleles for the development of allergy to lipocalin allergens such as the major dog allergen Can f 1 is not clear at present.

OBJECTIVE

To characterize the TCR Vbeta usage in the Can f 1-specific T cell lines and the HLA class II genotypes of Can f 1-allergic and non-allergic subjects.

METHODS

T cell lines were induced with recombinant Can f 1 from the peripheral blood mononuclear cells of 12 non-atopic dog owners and 26 dog-allergic patients. Thirteen of the dog-allergic subjects were sensitized to Can f 1. Expression of the TCR Vbeta subtypes on CD4(+) T cells in the T cell lines was measured by flow cytometry. The subjects were HLA genotyped for DRB1, DQB1 and DPB1 loci.

RESULTS

Can f 1-specific T cell lines were obtained from 18 subjects, with either positive (n=8) or negative (n=10) skin prick tests (SPTs) to recombinant Can f 1. The frequency of TCR Vbeta5.1(+) T cells was significantly higher in the T cell lines of subjects with negative SPTs to the allergen. Moreover, DR4-DQ8 haplotype was over-represented among these subjects.

CONCLUSION

The DR4-DQ8 haplotype and the TCR Vbeta5.1(+) CD4(+) T cells may be protective against allergy to Can f 1.

Clonotypic analysis of cerebrospinal fluid T cells during disease exacerbation and remission in a patient with multiple sclerosis

Migration of autoreactive T cells into the central nervous system (CNS) compartment is thought to be an important step in the pathogenesis of multiple sclerosis (MS). To follow the evolution of T cell repertoire in the CNS of a patient with relapsing-remitting MS, we analyzed cerebrospinal fluid (CSF) cells obtained during an acute clinical exacerbation, and subsequent disease remission after 13 months of immunomodulatory therapy. T cell receptor CDR3 region length distribution was significantly altered during the relapse, demonstrating the presence of clonally expanded T cells in the CSF. CDR3 spectratyping is a valuable approach to identify disease-associated T cells in the CNS.

Analysis of T-cell repertoire in hepatitis-associated aplastic anemia

Hepatitis-associated aplastic anemia (HAA) is a syndrome of bone marrow failure following an acute attack of seronegative hepatitis. Clinical features and liver histology suggest a central role for an immune-mediated mechanism. To characterize the immune response, we investigated the T-cell repertoire (T-cell receptor [TCR] Vβ chain subfamily) of intrahepatic lymphocytes in HAA patients by TCR spectratyping. In 6 of 7 HAA liver samples, a broad skewing pattern in the 21 Vβ subfamilies tested was observed. In total, 62% ± 18% of HAA spectratypes showed a skewed pattern, similar to 68% ± 18% skewed spectratype patterns in 3 of 4 patients with confirmed viral hepatitis. Additionally, the T-cell repertoire had similarly low levels of complexity. In the peripheral blood lymphocytes (PBLs) of a separate group of HAA patients prior to treatment, 60% ± 15% skewed spectratypes were detected, compared with only 18% ± 8% skewed spectratypes in healthy controls. After successful immunosuppressive treatment, an apparent reversion to a normal T-cell repertoire with a corresponding significant increase in T-cell repertoire complexity was observed in the HAA samples. In conclusion, our data suggest an antigen-driven T-cell expansion in HAA and achievement of a normal T-cell repertoire during recovery from HAA. (Blood. 2004;103:4588-4593)

Theiler's virus infection: a model for multiple sclerosis

Both genetic background and environmental factors, very probably viruses, appear to play a role in the etiology of multiple sclerosis (MS). Lessons from viral experimental models suggest that many different viruses may trigger inflammatory demyelinating diseases resembling MS. Theiler's virus, a picornavirus, induces in susceptible strains of mice early acute disease resembling encephalomyelitis followed by late chronic demyelinating disease, which is one of the best, if not the best, animal model for MS. During early acute disease the virus replicates in gray matter of the central nervous system but is eliminated to very low titers 2 weeks postinfection. Late chronic demyelinating disease becomes clinically apparent approximately 2 weeks later and is characterized by extensive demyelinating lesions and mononuclear cell infiltrates, progressive spinal cord atrophy, and axonal loss. Myelin damage is immunologically mediated, but it is not clear whether it is due to molecular mimicry or epitope spreading. Cytokines, nitric oxide/reactive nitrogen species, and costimulatory molecules are involved in the pathogenesis of both diseases. Close similarities between Theiler's virus-induced demyelinating disease in mice and MS in humans, include the following: major histocompatibility complex-dependent susceptibility; substantial similarities in neuropathology, including axonal damage and remyelination; and paucity of T-cell apoptosis in demyelinating disease. Both diseases are immunologically mediated. These common features emphasize the close similarities of Theiler's virus-induced demyelinating disease in mice and MS in humans.

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.

T cell receptor VB repertoire diversity in patients with immune thrombocytopenia following splenectomy

In recent years, a pathophysiological role for T cells in immune thrombocytopenia (ITP) has been established. We applied cDNA size distribution analysis of the T cell receptor (TCR) beta-variable (VB) complementarity-determining region 3 (CDR3) in order to investigate T cell repertoire diversity among immune thrombocytopenia patients who had either responded or not responded to splenectomy, and compared them to normal controls. ITP patients who had had a durable platelet response to splenectomy showed a mean 2.8 +/- 2.1 abnormal CDR3 size patterns per patient, similar to healthy volunteers (2.9 +/- 2.0 abnormal CDR3 size patterns). In contrast, patients unresponsive to splenectomy demonstrated evidence of significantly more clonal T cell expansions than patients who had responded to splenectomy or controls (11.3 +/- 3.3 abnormal CDR3 size patterns per patient; P < 0.001). Of the VB subfamilies analysed, VB3 and VB15 correlated with response or non-response to splenectomy, each demonstrating oligoclonality in non-responding patients (P < 0.05). These findings suggest that removal of the spleen may lead directly or indirectly to reductions in T cell clonal expansions in responders, or that the extent of T cell clonality impacts responsiveness to splenectomy in patients with ITP.

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.

Follow-up of the T-cell clonality in Sezary patients treated by extracorporeal photopheresis using a new assay: the immunoscope technique

Sezary syndrome is a leukemic form of epidermotropic cutaneous T-cell lymphoma related to the malignant proliferation of clonal CD4+ T-cells. Extracorporeal photochemotherapy (ECP) may induce a transient improvement of the clinical signs but it's efficiency is discussed. In order to investigate the T-cell clonality in the peripheral blood of patients with Sezary syndrome and to monitor its evolution in 8 patients treated by ECP, we used the Immunoscope technique. In one patient, we observed a decrease of the T-cell clonality from 15.6% to 0%, paralleling a complete remission of the clinical disease with a disappearance of the circulating Sezary cells. In the other cases, the evolution of the relative frequency paralleled the clinical status of the patient. In 3 cases, we observed a quick-acting direct cytotoxicity of the association 8MOP + UVA on the T-cell clone present in the cellular product. Immunoscope technique appears to be an efficient assay to appreciate the amount of tumoral cells and monitor the evolution of the clonal component in Sezary syndrome.

Evidence of clonotypic pattern of T-cell repertoire in synovial fluid of children with juvenile rheumatoid arthritis at the onset of the disease

Rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) are characterized by chronic inflammation, synovial cell proliferation and progressive joint damage. It has been speculated that T cells play an important role in the pathogenesis of RA and JRA in the early stage of the disease. Previous studies have demonstrated discrepant results regarding the significance of T-cell clonality in RA or JRA lesions. It can be postulated that the heterogeneity of these data may be linked to the stage of the disease, as the relative importance of selective immunological events is different during the time from onset to established disease. To avoid this problem, we conducted the present study in nine children affected by JRA at the onset of the disease and before treatment. We analysed the T-cell receptor beta chain variable (TCRBV) of CD4+ and CD8+ lymphocytes in peripheral blood (PBL) and synovial fluid (SFL), by a panel of monoclonal antibodies (MoAbs). Furthermore, to assess the clonotypic pattern of T-cell repertoire, the CDR3 length distribution was evaluated by spectratyping analysis. Our results showed no significant expansion of distinct TCRBV subset in either synovial or peripheral compartments. Conversely, when we studied the CDR3 length distribution, an oligoclonal pattern was found in the SFL of six patients, suggesting the presence of a clonotypic restriction of T cells in SFL, which is not detectable in PBL. These findings are consistent with an antigen driven T-cell expansion sequestered at the inflammatory site.

A prospective study on the evolution of the T-cell repertoire in patients with Sézary syndrome treated by extracorporeal photopheresis

Sézary syndrome is a leukemic form of epidermotropic cutaneous T-cell lymphoma related to the malignant proliferation of clonal CD4+ T cells. Extracorporeal photochemotherapy may induce a transient improvement of the clinical signs, but its efficiency is discussed. To investigate the frequency of the T-cell clone in the peripheral blood of patients with Sézary syndrome and to monitor its evolution in patients treated using extracorporeal photopheresis or chemotherapy, we used the immunoscope technique. In one patient, we observed a decrease of the relative frequency of the clone from 15.6% to 0%, paralleling a complete remission of the clinical disease and a disappearance of the circulating Sézary cells. In the other cases, the evolution of the relative frequency paralleled the initial improvement of the clinical status and the absence of long-term efficiency in patients treated with extracorporeal photopheresis or chemotherapy. We observed a quick-acting direct cytotoxicity of the association 8MOP + UVA on the T-cell clone. The immunoscope technique appears to be an efficient tool to appreciate the amount of tumoral cells and to monitor the evolution of the clonal component in the Sézary syndrome.

A prospective study on the evolution of the T-cell repertoire in patients with Sézary syndrome treated by extracorporeal photopheresis

Sézary syndrome is a leukemic form of epidermotropic cutaneous T-cell lymphoma related to the malignant proliferation of clonal CD4+ T cells. Extracorporeal photochemotherapy may induce a transient improvement of the clinical signs, but its efficiency is discussed. To investigate the frequency of the T-cell clone in the peripheral blood of patients with Sézary syndrome and to monitor its evolution in patients treated using extracorporeal photopheresis or chemotherapy, we used the immunoscope technique. In one patient, we observed a decrease of the relative frequency of the clone from 15.6% to 0%, paralleling a complete remission of the clinical disease and a disappearance of the circulating Sézary cells. In the other cases, the evolution of the relative frequency paralleled the initial improvement of the clinical status and the absence of long-term efficiency in patients treated with extracorporeal photopheresis or chemotherapy. We observed a quick-acting direct cytotoxicity of the association 8MOP + UVA on the T-cell clone. The immunoscope technique appears to be an efficient tool to appreciate the amount of tumoral cells and to monitor the evolution of the clonal component in the Sézary syndrome.

Antibody-mediated suppression of Vbeta5.2/5.3(+) T cells in multiple sclerosis: results from an MRI-monitored phase II clinical trial

The objective of this study was to evaluate the safety and efficacy of the humanized antibody ATM-027 in a baseline versus treatment magnetic resonance imaging-monitored study. Expansion of Vbeta5.2/5.3(+) T cells has been demonstrated in the peripheral blood, cerebrospinal fluid, and brain lesions of MS patients. In a phase I study, ATM-027 depleted these cells in peripheral blood and, in parallel, T-cell MBP reactivity and IFN-gamma expression were reduced. We studied 59 patients with relapsing-remitting MS (47 on ATM-027 and 12 on placebo) stratified for HLA-DR2 status. Monthly intravenous injections were given for 6 months. Individual dose titration was employed to obtain depletion of the target T-cell level and downregulation of antigen receptor density as monitored by flow cytometry. Five monthly magnetic resonance imaging scans were performed before treatment to establish baseline activity, six during treatment, and three during follow-up. Additional immunological assessments were performed to elucidate the mechanism of action of ATM-027. The treatment was safe and well tolerated, inducing consistent suppression of the target cell population. During run-in, active lesions were found in 78.7% (37/47) of patients treated with ATM-027. During treatment, the median number of lesions was reduced by 33% (p = 0.13) independent of DR2 status. The corresponding volume of enhancement was 221 mm(3) at baseline, with a reduction of 10% during treatment. Decreased numbers of cells expressing interferon-gamma messenger RNA, and decreased T-cell reactivity to several myelin antigens were found in ATM-027 treated patients. In conclusion, consistent suppression of Vbeta 5.2/5.3(+) T cells was achieved. However, the effect size on magnetic resonance imaging was considerably less than the targeted 60%.

Oligoclonal expansion of memory CD8+ T cells in cerebrospinal fluid from multiple sclerosis patients

Multiple sclerosis is a chronic inflammatory demyelinating disease of the CNS. Although the aetiology of multiple sclerosis is still unknown, it is widely believed that T cells play a central role in its pathogenesis. To identify and characterize disease-relevant T cells, we analysed CD4+ and CD8+ T cells freshly isolated from the CSF and peripheral blood of 36 multiple sclerosis patients for their T-cell receptor variable beta (TCRBV) chain repertoire. In most patients, we found significant overexpression of individual TCRBV chains on CD8+ T cells from CSF compared with peripheral blood. In contrast, only a few multiple sclerosis patients showed differences between the two compartments in TCRBV expression on CD4+ T cells. The overexpression of specific TCRBV chains on CD8+ T cells was found to be stable over several months in selected patients and involved mainly T cells with a memory phenotype. In two patients studied, individual TCRBV chain overexpression was found to be caused by the expansion of T cell populations with identical or highly similar rearranged T-cell receptor beta- and alpha-chain sequences, which were not found among peripheral blood CD8+ T cells. Our findings demonstrate selective enrichment of memory CD8+ T cells in the CSF of multiple sclerosis patients, suggesting a role for these CD8+ T cells in the pathogenesis of multiple sclerosis. Our study provides a basis for future trials to identify disease-associated antigens and disease pathogenesis in multiple sclerosis.

Depletion of Vbeta5.2/5.3 T cells with a humanized antibody in patients with multiple sclerosis

A potentially pathogenic expansion of T cells expressing T cell receptor (TCR) Vbeta5.2/5.3 has been demonstrated in patients with multiple sclerosis (MS). A humanized antibody (ATM-027) directed against these T cells has been developed to further investigate the role of this subpopulation of T cells in MS. The pharmacokinetics/dynamics and safety of ATM-027 (0.3-300 mg intravenously over 30 min) were investigated in 14 patients with MS. The effect of treatment on cytokine expression and autoreactivity to peptides of myelin basic protein (MBP) was also studied. ATM-027 was well tolerated and raised no safety concerns. Clearance of the antibody was low and elimination half-life was approximately 3 weeks. The majority of the target Vbeta5.2/5.3 expressing T cells were depleted for at least 18 months. The small remaining fraction of target cells showed a marked decrease in their TCR expression, which was recovered within 8 months. The numbers of peripheral blood mononuclear cells (PBMCs) with spontaneous expression of IFN-gamma was decreased at 72 h and 8 weeks after treatment, whilst no clear effects on TNF-alpha, IL-4, IL-10, TGF-beta expression were observed. There was also a significant decrease in the number of PBMCs producing IFN-gamma in response to MBP peptide 80-102. We conclude that long-term depletion of T cells expressing defined Vbeta subgroups in MS patients is feasible using selective immunotherapy. The selective depletion of Vbeta5.2/5.3 expressing T cells in this study resulted in a decrease in potentially disease promoting anti-MBP reactivity and pro-inflammatory cytokine production.

Colitis-related public T cells are selected in the colonic lamina propria of IL-10-deficient mice

IL-10 is an important regulatory cytokine in the mucosal immune system, as supported by the fact that mice deficient in IL-10 spontaneously develop Crohn's disease-like colitis. An aberrant, Th1-driven CD4(+) T-cell response to enteric bacteria seems to be important in the pathogenesis of this murine colitis. However, no specific bacteria or bacterial products have been identified, and whether the colitis is mediated by the activation of CD4(+) T cells that recognize specific peptide-MHC complexes is controversial. In this study, we analyzed the TCR beta chain complementarity determining region 3 length spectratype of colonic CD4(+) T cells isolated from diseased IL-10-deficient mice by using the Immunoscope technique. Screening of the diseased interleukin-10-deficient mice resulted in a restricted clonotype in TCR V beta 13 and 14 subfamilies of colonic CD4(+) T cells. In contrast, a Gaussian distribution of clonotype of individual TCR V beta subsets was observed in CD4(+) T cells from the peripheral lymphoid tissues. Although individual variability in the disease-related response was also noted in other IL-10-deficient mice maintained in La Jolla and Osaka, perhaps because of different stages of the disease, genetic background, or the housing environment, colitis-related public clones seemed to be shared in all the diseased mice tested. To address whether public clones were involved, we determined the DNA sequence of the clones. Public motifs were shared in colonic CD4(+) T cells from different background interleukin-10-deficient mice with colitis. The frequently found motifs were SXDWG and SATGNYAEQ. These motifs were not seen in the peripheral lymphoid tissues of diseased mice as well as the colon of non-diseased mice. Thus, the common motif may be related to a public gut-derived antigen, which could be important for the development of pathogenic CD4(+) T cells in this inflammatory bowel disease (IBD) model. The selection of V beta-J beta usage is perhaps stochastic in individual mice; however, the epigenetic generation of SXDWG motif by the recombination machinery and selection for this motif in the gut environment could be important for triggering IBD.

Preferential survival of an MBP-specific T cell clone in an HLA-DR2 multiple sclerosis patient

Anti-myelin basic protein (MBP) autoreactive T cells play a key role in the pathogenesis of multiple sclerosis. Thus, we applied the Immunoscope strategy to cerebrospinal fluid (CSF) and peripheral blood lymphocytes (PBLs) of an HLA-DR2 patient. Both compartments showed major expansion for the V(beta)13S5 chain, which was associated in peripheral blood with significant proliferation of PBLs in response to MBP and the 84-102 HLA-DR2-restricted peptide. Sequencing revealed a unique nucleotide sequence in the CSF that gives rise to the amino acid sequence V(beta)13S5-RPGQGDQETQ-J(beta)2.5 if translated. This CDR3 sequence had already been reported to be reactive against the 84-102 peptide. This specific sequence was not detected in PBLs on day 0, whereas it was readily detectable on day 6 culture samples. Thus, cell culture may lead to enrichment in a T cell clone identified as autoreactive.

Presence of oligoclonal T cells in cerebrospinal fluid of a child with multiphasic disseminated encephalomyelitis following hepatitis A virus infection

We have investigated the clonality of beta-chain T-cell receptor (TCR) transcripts from the cerebrospinal fluid (CSF) and peripheral blood from a 7-year old child who developed a multiphasic disseminated encephalomyelitis following an infection with hepatitis A virus. We amplified beta-chain TCR transcripts by nonpalindromic adaptor (NPA)-PCR-Vbeta-specific PCR. TCR transcripts from only five Vbeta families (Vbeta13, Vbeta3, Vbeta17, Vbeta8, and Vbeta20) were detected in CSF. The amplified products were combined, cloned, and sequenced. Sequence analysis revealed in the CSF substantial proportions of identical beta-chain of TCR transcripts, demonstrating oligoclonal populations of T cells. Seventeen of 35 (48%) transcripts were 100% identical, demonstrating a major Vbeta13.3 Dbeta2.1 Jbeta1.3 clonal expansion. Six of 35 (17%) transcripts were also 100% identical, revealing a second Vbeta13 clonal expansion (Vbeta13.1 Dbeta2.1 Jbeta1.2). Clonal expansions were also found within the Vbeta3 family (transcript Vbeta3.1 Dbeta2.1 Jbeta1.5 accounted for 5 of 35 transcripts [14%]) and within the Vbeta20 family (transcript Vbeta20.1 Dbeta1.1 Jbeta2.4 accounted for 3 of 35 transcripts [8%]). These results demonstrate the presence of T-cell oligoclonal expansions in the CSF of this patient following infection with hepatitis A virus. Analysis of the CDR3 motifs revealed that two of the clonally expanded T-cell clones exhibited substantial homology to myelin basic protein-reactive T-cell clones. In contrast, all Vbeta TCR families were expressed in peripheral blood lymphocytes. Oligoclonal expansions of T cells were not detected in the peripheral blood of this patient. It remains to be determined whether these clonally expanded T cells are specific for hepatitis A viral antigen(s) or host central nervous system antigen(s) and whether molecular mimicry between hepatitis A viral protein and a host protein is responsible for demyelinating disease in this patient.

In vitro T-cell receptor V beta repertoire analysis may identify which T-cell V beta families mediate graft-versus-leukaemia and graft-versus-host responses after human leucocyte antigen-matched sibling stem cell transplantation

We studied oligoclonal T-cell expansions of 24 T-cell receptor (TCR) V beta families in normal donor lymphocytes stimulated with patient's cells and in recipient blood after transplant, using a polymerase chain reaction-based assay (spectratyping). T cells from donor blood were incubated with separated myeloid leukaemia cells or T cells from the HLA-identical sibling recipient. In five of the six patients tested, the T-cell V beta skewing pattern observed in vitro was seen in vivo after transplant. After transplant, the myeloid-specific V beta skewing coincided with the disappearance of residual disease in three patients and in one patient skewing was lost at the time of leukaemic relapse. In functional tests, T cells generated against leukaemic cells in vitro produced interferon gamma in response to the leukaemia. Removal of the leukaemia-expanded skewed V beta families significantly decreased cytotoxic killing of the leukaemia. However, while there was a general concordance in the V beta family exhibiting clonal expansion in vitro and in vivo, the exact clonotype expanded in vitro and in vivo differed. These findings suggest that alloresponses involve multiple T-cell clones within a restricted TCR V beta repertoire that undergo different selection pressures in vitro and in vivo.

TCR peptide therapy in human autoimmune diseases

Inflammatory Th1 cells reacting to tissue/myelin derived antigens likely contribute to the pathogenesis of diseases such as multiple sclerosis (MS), rheumatoid arthritis (RA), and psoriasis. One regulatory mechanism that may be useful for treating autoimmune diseases involves an innate second set of Th2 cells specific for portions of the T cell receptor of clonally expanded pathogenic Th1 cells. These Th2 cells are programmed to respond to internally modified V region peptides from the T cell receptor (TCR) that are expressed on the Th1 cell surface in association with major histocompatibility molecules. Once the regulatory Th2 cells are specifically activated, they may inhibit inflammatory Th1 cells through a non-specific bystander mechanism. A variety of strategies have been used by us to identify candidate disease-associated TCR V genes present on pathogenic Th1 cells, including BV5S2, BV6S5, and BV13SI in MS, BV3, BV14, and BV17 in RA, and BV3 and BV13S1 in psoriasis. TCR peptides corresponding to the mid region of these BV genes were found to be consistently immunogenic in vivo when administered either i.d. in saline or i.m. in incomplete Freund's adjuvant (IFA). In MS patients, repeated injection of low doses of peptides (100-300 microg) significantly boosted the number of TCR-reactive Th2 cells. These activated cells secreted cytokines, including IL-10, that are known to inhibit inflammatory Th1 cells. Cytokine release could also be induced in TCR-reactive Th2 cells by direct cell-cell contact with Th1 cells expressing the target V gene. These findings indicate the potential of regulatory Th2 cells to inhibit not only the target Th1 cells, but also bystander Th1 cells expressing different V genes specific for other autoantigens. TCR peptide vaccines have been used in our studies to treat a total of 171 MS patients (6 trials), 484 RA patients (7 trials), and 177 psoriasis patients (2 trials). Based on this experience in 824 patients with autoimmune diseases, TCR peptide vaccination is safe and well tolerated, and can produce significant clinical improvement in a subset of patients that respond to immunization. TCR peptide vaccination represents a promising approach that is well-suited for treating complex autoimmune diseases.

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.

Abnormal T-cell repertoire is consistent with immune process underlying the pathogenesis of paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal disorder of the hematopoietic stem cell (HSC). Somatic mutations in thePIG-A gene result in the deficiency of several glycosylphosphatidylinositol-linked proteins from the surface of blood cells. This explains intravascular hemolysis but does not explain the mechanism of bone marrow failure that is almost invariably seen in PNH. In view of the close relationship between PNH and idiopathic aplastic anemia (IAA), it has been suggested that the 2 disorders might have a similar cellular pathogenesis, namely, that autoreactive T-cell clones are targeting HSCs. In this paper, we searched for abnormally expanded T-cell clones by size analysis of the complementarity-determining region 3 (CDR3) in the beta variable chain (BV) messenger RNA (mRNA) of the T-cell receptor (TCR) in 19 patients with PNH, in 7 multitransfused patients with hemoglobinopathy. and in 11 age-matched healthy individuals. We found a significantly higher degree of skewness in the TCR BV repertoire of patients with PNH, compared with controls (R2 values 0.82 vs 0.91,P &lt; .001). The mean frequency of skewed families per individual was increased by more than 2-fold in patients with PNH, compared with controls (28% ± 19.6% vs 11.4% ± 6%,P = .002). In addition, several TCR BV families were significantly more frequently skewed in patients with PNH than in controls. These findings provide experimental support for the concept that PNH, like IAA, has an immune pathogenesis. In addition, the identification of expanded T-cell clones by CDR3 size analysis will help to investigate the effect of HSC-specific T cells on normal and PNH HSCs.

Abnormal T-cell repertoire is consistent with immune process underlying the pathogenesis of paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal disorder of the hematopoietic stem cell (HSC). Somatic mutations in thePIG-A gene result in the deficiency of several glycosylphosphatidylinositol-linked proteins from the surface of blood cells. This explains intravascular hemolysis but does not explain the mechanism of bone marrow failure that is almost invariably seen in PNH. In view of the close relationship between PNH and idiopathic aplastic anemia (IAA), it has been suggested that the 2 disorders might have a similar cellular pathogenesis, namely, that autoreactive T-cell clones are targeting HSCs. In this paper, we searched for abnormally expanded T-cell clones by size analysis of the complementarity-determining region 3 (CDR3) in the beta variable chain (BV) messenger RNA (mRNA) of the T-cell receptor (TCR) in 19 patients with PNH, in 7 multitransfused patients with hemoglobinopathy. and in 11 age-matched healthy individuals. We found a significantly higher degree of skewness in the TCR BV repertoire of patients with PNH, compared with controls (R2 values 0.82 vs 0.91,P < .001). The mean frequency of skewed families per individual was increased by more than 2-fold in patients with PNH, compared with controls (28% ± 19.6% vs 11.4% ± 6%,P = .002). In addition, several TCR BV families were significantly more frequently skewed in patients with PNH than in controls. These findings provide experimental support for the concept that PNH, like IAA, has an immune pathogenesis. In addition, the identification of expanded T-cell clones by CDR3 size analysis will help to investigate the effect of HSC-specific T cells on normal and PNH HSCs.

Residual public repertoires to self

The consensus view about the constitution of the T cell receptor repertoire has shifted greatly even during this decade. Although the discovery of autoimmunity in the fifties had clearly shown that a repertoire must exist directed against self antigens, the extent of this repertoire was not fully appreciated. In our work we have tried to elucidate the nature of the antigenic specificities against which this self-directed repertoire is directed. The non-tolerized (residual) self-directed repertoire is a direct consequence of the hierarchy of antigenic determinant display, and is the most important influence in the organism's choice of which T cells to delete. Certain determinants remain "silent" and are neither displayed in the thymus nor in the periphery: these are a heterogeneous group which are invisible to T cells for a variety of reasons. One reason relates to the processing and presentation of determinants, and a second derives from the nature of the T cell receptor (TcR) and the avidity of the T cell for its target specificity.

Systemic activation and antigen-driven oligoclonal expansion of T cells in a mouse model of colitis

Transfer of CD4+CD45RBhigh T cells into immunodeficient mice results in both the expansion of the transferred T cells and colitis. Here we show that colitis pathogenesis requires expression of MHC class II molecules by the immune-deficient host. Analysis of the TCRbeta repertoire of the cells found in the large intestine of diseased mice revealed a population with restricted TCR diversity. Furthermore, nucleotide sequence analysis demonstrated the selection for particular CDR3beta amino acid sequence motifs. Collectively, these data indicate that the expansion of T cells in the intestine and colitis pathogenesis are likely to require the activation of Ag-specific T cells, as opposed to nonspecific or superantigen-mediated events. There is relatively little overlap, however, when the TCR repertoires of different individuals are compared, suggesting that a number of Ags can contribute to T cell expansion and the generation of a T cell population in the intestine. Surprisingly, many of the expanded clones found in the large intestine also were found in the spleen and elsewhere, although inflammation is localized to the colon. Additionally, donor-derived T cells appear to be activated in both the intestine and the spleen at early time points after cell transfer. Together, these results strongly suggest that disease induction in this model involves either the early and systemic activation of antigen-specific T cells or the rapid dispersal of T cells activated at a particular site.

T cell receptor V genes in multiple sclerosis: increased use of TCRAV8 and TCRBV5 in MBP-specific clones

It is probable that myelin-reactive T cells, including those specific for myelin basic protein (MBP) contribute to the pathogenesis of multiple sclerosis (MS). Although many studies have characterized the specificity, MHC restriction, and V gene use of MBP-specific T cells, there is little agreement as to whether there are differences between MS and controls, and how HLA-DR2, a risk factor for MS, might influence selection of MBP-specific T cells. We here discuss models in which MHC class II alleles could help shape the TCR repertoire, and then review more than 750 clones reported in the literature. The major finding from our analysis is that both TCRAV8 and BV5, but not BV6 were utilized more frequently in MS patients than non-MS patients in response to MBP, although no differences were found between DR2+ versus DR2- donors. These data indicate HLA-independent differences in the T cell repertoire between MS patients and controls that may be important for targeted TCR-based therapy. Moreover, we conclude that (1) HLA-DR alleles preferentially restrict MBP responses, although MS patients tend to use HLA-DQ and -DP alleles more often than control donors; (2) HLA-DR2 alleles are used to restrict only about half the MBP responses in MS patients, significantly less than in control patients; (3) the DRB1*1501 and DRB5*0101 subtypes within the Dw2 haplotype are used relatively equally to restrict MBP responses. In this context, we review the results of our previous clinical trials in progressive MS patients, demonstrating the ability of TCRBV5S2 peptides to induce clinically relevant regulatory responses that inhibit MBP-specific Th1 cells through a bystander suppression mechanism.

T-cell repertoire analysis in chronic plaque psoriasis suggests an antigen-specific immune response

Psoriasis is a chronic inflammatory cutaneous disease of unknown etiology. Activation of T cells is thought to play a major role in the pathophysiology of psoriasis. In order to gain insight into the nature of the antigen (superantigen or nominal protein antigen) involved in psoriatic lesions, we have used a RT-PCR method to analyze the frequency of the 24 T cell receptor V beta chain (TCRBV) subfamilies and the size of the antigen-binding region (CDR3), using the immunoscope assay, in skin lesions of patients with chronic plaque-type psoriasis. Semi-quantitative analysis showed that no significant difference in V beta subfamily usage could be detected in T lymphocytes infiltrating lesional skin as compared to blood lymphocytes. Alternatively, determination of the size distribution of the CDR3 of all the V beta subfamilies revealed only in psoriatic skin a marked TCR oligoclonality defined by the presence in 3 to 5 V beta subfamilies of a single predominant CDR3 size which was associated with a unique V beta-J beta combination. Identical patterns of CDR3 length and V beta-J beta combination profiles were found in symetrical lesional sites from two psoriatic patients. This type of skewed CDR3 size profile is reminiscent of a local stimulation of T lymphocytes by nominal protein antigens. These data suggest that T lymphocytes infiltrating plaque-type psoriatic skin comprise expansions of oligoclonal T cells in response to stimulation by an antigen present in the skin.

T-cell clonality in immune responses

Recent methodological advances allow the analysis of clonal composition within T-cell subsets. Here, Mala Maini and colleagues review the available data on clonality in acute immune responses and steady-state situations. They highlight and explore reasons for the striking differences in clonality between the CD4+ and CD8+ T-cell subsets.

Characterization of T-Cell Repertoire of the Bone Marrow in Immune-Mediated Aplastic Anemia: Evidence for the Involvement of Antigen-Driven T-Cell Response in Cyclosporine-Dependent Aplastic Anemia

To determine whether the antigen-driven T-cell response is involved in the pathogenesis of aplastic anemia (AA), we examined the complementarity-determining region 3 (CDR3) size distribution of T-cell receptor (TCR) β-chain (BV) subfamilies in the bone marrow (BM) of untreated AA patients. AA patients who did not respond to immunosuppressive therapy and those who obtained unmaintained remission early after cyclosporine (CyA) or antithymocyte globulin (ATG) therapy exhibited essentially a normal CDR3 size pattern. In contrast, five patients who needed continuous administration of CyA to maintain remission exhibited a skewed CDR3 size pattern in a number (>40%) of BV subfamilies suggestive of clonal predominance. The skewing of CDR3 size distribution became less pronounced in one of the CyA-dependent patients when the patient achieved unmaintained remission after a 4-year therapy with CyA, whereas it persisted longer than 7 years in the other patient requiring maintenance therapy. Sequencing of BV15 cDNA for which the CDR3 size pattern exhibited apparent clonal predominance in all CyA-dependent patients showed high homology of the amino acid sequence of the CDR3 between two different patients. These findings indicate that antigen-driven expansion of T cells is involved in the pathogenesis of AA characterized by CyA-dependent recovery of hematopoiesis.

Characterization of T-Cell Repertoire of the Bone Marrow in Immune-Mediated Aplastic Anemia: Evidence for the Involvement of Antigen-Driven T-Cell Response in Cyclosporine-Dependent Aplastic Anemia

To determine whether the antigen-driven T-cell response is involved in the pathogenesis of aplastic anemia (AA), we examined the complementarity-determining region 3 (CDR3) size distribution of T-cell receptor (TCR) β-chain (BV) subfamilies in the bone marrow (BM) of untreated AA patients. AA patients who did not respond to immunosuppressive therapy and those who obtained unmaintained remission early after cyclosporine (CyA) or antithymocyte globulin (ATG) therapy exhibited essentially a normal CDR3 size pattern. In contrast, five patients who needed continuous administration of CyA to maintain remission exhibited a skewed CDR3 size pattern in a number (&gt;40%) of BV subfamilies suggestive of clonal predominance. The skewing of CDR3 size distribution became less pronounced in one of the CyA-dependent patients when the patient achieved unmaintained remission after a 4-year therapy with CyA, whereas it persisted longer than 7 years in the other patient requiring maintenance therapy. Sequencing of BV15 cDNA for which the CDR3 size pattern exhibited apparent clonal predominance in all CyA-dependent patients showed high homology of the amino acid sequence of the CDR3 between two different patients. These findings indicate that antigen-driven expansion of T cells is involved in the pathogenesis of AA characterized by CyA-dependent recovery of hematopoiesis.

Common Intra-Articular T Cell Expansions in Patients with Reactive Arthritis: Identical β-Chain Junctional Sequences and Cytotoxicity Toward HLA-B27

Spondyloarthropathies constitute a group of autoimmune diseases of special interest because of their tight association with the MHC class I molecule HLA-B27 and the bacterial triggering of some clinical forms called reactive arthritis (ReA). One current hypothesis is the presentation by HLA-B27 of a so-called arthritogenic peptide to T cells. To better focus on the relevant T cell populations within the joint, we performed an extensive β-chain T cell repertoire analysis of synovial fluid compared with PBL in seven patients, four of whom were characterized as having ReA triggered by Yersinia enterocolitica, Chlamydia trachomatis, or Shigella sonnei. Analysis of the size diversity of the β-chain complementarity-determining region 3 (CDR3) allowed us to evaluate the degree of T cell clonality in the samples. Oligoclonal T cell expansions were frequently observed in the joint. In one patient, CDR3 amino acid sequences of major expansions using two different BV genes were identical. One dominant T cell expansion and several CDR3 amino acid sequences were identical in two different patients. Furthermore, one sequence was identical with a sequence reported independently in a Salmonella-induced ReA patient. Together, these data indicate a surprisingly high degree of conservation in the T cell responses in recent-onset ReA triggered by different micro-organisms. A CD8+ synovial line expressing shared clonotypes was established and reacted toward several B*2705 lymphoblastoid cell lines, therefore supporting a molecular mimicry phenomenon at the T cell level in the disease mechanism.

Immune-Mediated Destruction of Melanocytes in Halo Nevi Is Associated with the Local Expansion of a Limited Number of T Cell Clones

The β-chain repertoire of the T cells that infiltrate spontaneously regressing nevi (the halo nevus phenomenon) was studied. In addition to the infiltration of the halo nevi by cutaneous lymphocyte-associated Ag-positive lymphocytes, oligoclonal expansion of T cells was observed in all halo nevi of all patients. T cells using the same TCR β-chain were observed in distinct halo nevi of the same patient but not in his peripheral blood, demonstrating a local expansion of common clones that are most likely activated by the Ag(s) shared by independent halo nevi of the same patient.

A comparison of two techniques for the molecular tracking of specific T-cell responses; CD4+ human T-cell clones persist in a stable hierarchy but at a lower frequency than clones in the CD8+ population

Oligoclonal or clonal T-cell expansions, presumed to be antigen driven, are frequently sought and followed for diagnostic and prognostic purposes, as well as to understand more about their natural history. Techniques based on conservation of T-cell receptor CDR3 length are increasingly widely used, often without assessment of sensitivity or specificity. We present a comparative evaluation of a novel modified heteroduplex technique and a CDR3-length-based assay. Dilution of a known clone in a mixed T-cell population shows that in our hands the heteroduplex technique is at least 10-fold more sensitive than the CDR3-length-based assay. However, even with this level of sensitivity, we do not detect clonal expansions in unstimulated CD4+ T cells. This contrasts with the frequent detection of CD8+ clones in fresh samples and suggests different mechanisms of clonal homeostasis in the two subsets. We show that both techniques detect functional expansions after in vitro stimulation with a recall antigen. The distinct molecular footprint seen with the heteroduplex technique allows reproducible follow up of specific clonal expansions. We have exploited this to demonstrate that the repertoire of clones expanded by in vitro tetanus toxoid stimulation shows stability within an individual, implying long-term maintenance of multiple CD4+ clones.

T cell receptor V beta 5 and V beta 17 clonal diversity in cerebrospinal fluid and peripheral blood lymphocytes of multiple sclerosis patients

To better characterize the cellular immune response taking place in the MS central nervous system, we investigated the blood and CSF T cell receptor (TCR) V beta 5 and V beta 17 repertoire in HLA-typed patients with recently diagnosed MS or other neurological diseases (OND). Using a RT-PCR based technique, we analysed directly ex vivo the CDR3 size of TCR beta chains utilizing V beta 5 (eight patients with MS and one with OND) or V beta 17 (eight patients with MS and six with OND) gene segments on paired blood-CSF samples. Globally, the analysis of V beta 5-J beta and V beta 17-J beta repertoire showed a less diverse pattern in the CSF samples than in the corresponding peripheral blood lymphocytes both in MS and in OND patients. However, we did not detect any recurrent clonal expansion within the V beta 5+ T cells in MS patients, underlining the potential limits of V beta 5-based immunotherapy in MS. We found an expanded T cell population using the same V beta 17-J beta 1.6 combination with identical CDR3 length in the CSF of three MS patients and none of the control patients. These results suggest selective expansion of T cells expressing this segment gene in the MS central nervous system.

Quantitative analysis of the T cell repertoire selected by a single peptide-major histocompatibility complex

The positive selection of CD4+ T cells requires the expression of major histocompatibility complex (MHC) class II molecules in the thymus, but the role of self-peptides complexed to class II molecules is still a matter of debate. Recently, it was observed that transgenic mice expressing a single peptide-MHC class II complex positively select significant numbers of diverse CD4+ T cells in the thymus. However, the number of selected T cell specificities has not been evaluated so far. Here, we have sequenced 700 junctional complementarity determining regions 3 (CDR3) from T cell receptors (TCRs) carrying Vbeta11-Jbeta1.1 or Vbeta12-Jbeta1.1 rearrangements. We found that a single peptide-MHC class II complex positively selects at least 10(5) different Vbeta rearrangements. Our data yield a first evaluation of the size of the T cell repertoire. In addition, they provide evidence that the single Ealpha52-68-I-Ab complex skews the amino acid frequency in the TCR CDR3 loop of positively selected T cells. A detailed analysis of CDR3 sequences indicates that a fraction of the beta chain repertoire bears the imprint of the selecting self-peptide.

Lack of over-expression of T cell receptor Vbeta5.2 in myelin basic protein-specific T cell lines derived from HLA-DR2 positive multiple sclerosis patients and controls

Based on studies reporting an overexpression of certain V genes in myelin basic protein (MBP)-specific T cells from MS patients, immunotherapies targeting single TCR (Vbeta5.2, Vbeta6.1) are currently under way. In order to assess the basic assumption for one of these therapeutic strategies, i.e. the overexpression of Vbeta5.2 by MBP-specific T cells, we analyzed 100 MBP-specific T cell lines (TCL) for Vbeta5.2 expression. Only 4 out of 100 TCL expressed Vbeta5.2, and expression of this TCR gene is therefore not more frequent than expected from the normal peripheral blood distribution.

Comparative sequence analysis of the human T cell receptor beta chain in juvenile rheumatoid arthritis and juvenile spondylarthropathies: evidence for antigenic selection of T cells in the synovium

OBJECTIVE

To identify features of the T cell receptors (TCRs) present on clonally expanded T cells in the joints of patients with similar types of childhood rheumatic disease. Vbeta8 and Vbeta20 TCRs were selected as prototypic for polyarticular juvenile rheumatoid arthritis (JRA) and pauciarticular/juvenile spondylarthropathy (SpA), respectively.

METHODS

The portion of the TCR beta chain involved in antigen recognition in the synovial tissue, synovial fluid, and peripheral blood from patients with JRA and juvenile SpA was cloned and sequenced. The frequency of expanded clonotypes, size of expansions, the Jbeta region, and sequence motifs were determined for >2,000 sequences.

RESULTS

The majority of Vbeta20 and Vbeta8 clonal expansions were found in the joint rather than the peripheral blood. While instances of both Vbeta8 and Vbeta20 clonal expansion were detected in all disease types, the features of these expanded clonotypes were specific for disease type and Vbeta family. For example, Vbeta20 clonal expansion was characterized by many small expanded clonotypes in samples from patients with pauciarticular JRA and juvenile SpA while single large Vbeta8-specific expansions were found only in patients with polyarticular disease. Motifs specific to individual patients were identified, and for Vbeta20 clonotypes, a motif was found in synovial tissue samples.

CONCLUSION

Identification of common TCR features in oligoclonal expansions within individual patients and between patients with the same type of JRA suggests the recognition of a common or limited group of antigens in these diseases.