OX-40 antibody enhances for autoantigen specific V beta 8.2+ T cells within the spinal cord of Lewis rats with autoimmune encephalomyelitis

The V beta 8.2 T cell receptor (TCR) component is the predominant V beta gene product associated with antigen specific CD4+ T cell response to the major encephalitogenic epitope of myelin basic protein (MBP) in Lewis rats. Lewis rats were actively immunized with MBP in complete Freund's adjuvant and the V beta 8.2 positive and negative cells were analyzed for IFN-gamma mRNA production and OX-40 cell surface expression during the onset of EAE. The V beta 8.2+ T cells isolated from the spinal cord produced the majority of mRNA for IFN-gamma and also showed a marked enhancement for OX-40 expression compared to V beta 8.2+ T cells isolated from the lymph nodes. Only a fraction of IL-2 receptor positive T cells examined ex vivo from the inflammatory compartments co-expressed the OX-40 antigen. These results suggested that OX-40 cell surface expression could be used to identify and isolate the most recently activated T cells ex vivo. OX-40+ T cells isolated from the spinal cord were highly enriched for the V beta 8.2 T cell receptor component compared to OX-40- or unsorted spinal cord lymphocytes. OX-40+ T cells isolated from the spinal cord had an enhanced response to MBP, whereas OX-40+ cells isolated from the lymph nodes responded to both MBP and purified protein derivative. These data suggest that activated T cells can be isolated and characterized with the OX-40 antibody which only respond to the antigens present at the local site. The data also imply that isolation of OX-40+ T cells will be useful in identifying V beta biases and autoantigen specific cells within inflamed tissues even when the antigen specificity is unknown.

Myelin antigen-coupled splenocytes suppress experimental autoimmune encephalomyelitis in Lewis rats through a partially reversible anergy mechanism

Mechanisms of adult tolerance induced by injecting myelin Ag/ECDI (ethyl carbodiimide)-coupled splenocytes (Ag-SPL) were evaluated in Lewis rat experimental autoimmune encephalomyelitis (EAE). Rats could be tolerized against the major encephalitogenic epitope of guinea pig basic protein (Gp-BP), residues 72-89, using either S72-89-SPL or crude spinal cord homogenate (SCH)-SPL. In contrast to lymph node responses that were not affected significantly, the proliferation responses of blood T cells were markedly inhibited at the peak of EAE and during the recovery period to both Gp-BP and S72-89, but not to purified protein derivative (PPD), demonstrating Ag-specific tolerance. Tolerance induction reduced the number of infiltrating spinal cord (SC) cells, especially recruited CD45RC+ cells, as well as SC proliferation responses to S72-89 throughout the course of EAE. In contrast, SC response to PPD was increased at onset of EAE, but later during recovery the PPD response was also decreased compared with control rats. Tolerance induced by S72-89-SPL in blood and SC T cells could be reversed by incubation in IL-2, in accordance with an anergy model. BP-specific T cells preincubated in vitro with Gp-BP-SPL were rendered unresponsive to Gp-BP or S72-89, compared with the same T cells preincubated with histone (Hist)-SPL that remained Ag responsive. Consistent with an anergy model, preincubation with BP-SPL+IL-2 partially prevented tolerance induction to BP. T cells tolerized in vitro to BP-SPL induced milder EAE with delayed onset compared with control-tolerized T cells that produced lethal disease. These results demonstrate the efficacy of myelin Ag-coupled SPL in preventing EAE by selective tolerization of encephalitogenic T cells through a partially reversible anergy-induction mechanism.

Myelin antigen-coupled splenocytes suppress experimental autoimmune encephalomyelitis in Lewis rats through a partially reversible anergy mechanism

Mechanisms of adult tolerance induced by injecting myelin Ag/ECDI (ethyl carbodiimide)-coupled splenocytes (Ag-SPL) were evaluated in Lewis rat experimental autoimmune encephalomyelitis (EAE). Rats could be tolerized against the major encephalitogenic epitope of guinea pig basic protein (Gp-BP), residues 72-89, using either S72-89-SPL or crude spinal cord homogenate (SCH)-SPL. In contrast to lymph node responses that were not affected significantly, the proliferation responses of blood T cells were markedly inhibited at the peak of EAE and during the recovery period to both Gp-BP and S72-89, but not to purified protein derivative (PPD), demonstrating Ag-specific tolerance. Tolerance induction reduced the number of infiltrating spinal cord (SC) cells, especially recruited CD45RC+ cells, as well as SC proliferation responses to S72-89 throughout the course of EAE. In contrast, SC response to PPD was increased at onset of EAE, but later during recovery the PPD response was also decreased compared with control rats. Tolerance induced by S72-89-SPL in blood and SC T cells could be reversed by incubation in IL-2, in accordance with an anergy model. BP-specific T cells preincubated in vitro with Gp-BP-SPL were rendered unresponsive to Gp-BP or S72-89, compared with the same T cells preincubated with histone (Hist)-SPL that remained Ag responsive. Consistent with an anergy model, preincubation with BP-SPL+IL-2 partially prevented tolerance induction to BP. T cells tolerized in vitro to BP-SPL induced milder EAE with delayed onset compared with control-tolerized T cells that produced lethal disease. These results demonstrate the efficacy of myelin Ag-coupled SPL in preventing EAE by selective tolerization of encephalitogenic T cells through a partially reversible anergy-induction mechanism.

Antigen-specific T-cell activations distinguished by in vivo anti-CD4 antibody treatment

This study identifies activation characteristics of PPD-responsive T-cells that emerge after treatment with anti-CD4 monoclonal antibody (Mab). PPD-stimulated T-cell proliferations, OX40 phenotype and protein tyrosine phosphorylations involving p56lck (pp56lck) were compared to Con A stimulations using T-cells isolated from spleen and draining lymph node of CFA/PPD-immunized rats either untreated or treated in vivo with anti-CD4 Mab. Splenocytes stimulated by concanavalin A (Con A) showed correlated increases in proliferation, levels of pp56lck, and OX40 expression; these parameters were not correlated in splenocytes after PPD-stimulations. T-cells isolated from lymph nodes draining the site of CFA/PPD immunization proliferated in response to stimulation by either PPD or Con A, but only PPD-responsive cells showed correlation to the OX40 activation phenotype and increased levels of pp56lck. CD4+ T-cells isolated from either tissue compartment after anti-CD4 Mab treatments showed higher background and PPD-stimulated proliferations, and expressed lower levels of OX40. In contrast, anti-CD4 Mab treatments reduced (60%) and abolished Con A-stimulated proliferations of splenocytes and lymph node T-cells, respectively. The effects of anti-CD4 Mab treatment on pp56lck levels correlated only to the changes observed for Con A stimulations of splenocytes. These results demonstrate that PPD antigen-specific T-cell populations recovered from different tissue compartments were resistant to in vivo anti-CD4 Mab treatments and did not show the activation changes characteristics of CD4+ T-cells after Con A stimulation.

Analysis of V beta 8.2 CDR3 sequences from spinal cord T cells of Lewis rats vaccinated or treated with TCR V beta 8.2-39-59 peptide

Experimental autoimmune encephalomyelitis (EAE) in the Lewis rat can be induced with the administration of Gp-BP. This disease appears to be mediated at least in part by V beta 8.2+CD4+T cells, which specifically recognize the BP72-89 encephalitogenic peptide. Treatment or protection with V beta 8.2 CDR2 39-59 peptide can suppress or prevent clinical signs of EAE, presumably through the activation of regulatory T cells. Interestingly, V beta 8.2+ T cells continue to persist in the spinal cord of protected animals, although their appearance in the central nervous system (CNS) is delayed when compared with control animals with EAE. As part of our effort to elucidate the mechanism(s) of peptide protection and therapy, we sought to determine whether the V beta 8.2+ T cells in the spinal cord of protected or treated rats were truly representative of those found in rats with clinical EAE. Therefore, we examined the following CNS samples for the Asp96Ser97 motif, which has been identified previously in V beta 8.2+ BP-specific, encephalitogenic T cell clones: 1) rats protected with V beta 8.2-39-59 peptide, 2) rats treated with V beta 8.2-39-59 peptide, and 3) control rats with EAE. Our findings indicate that EAE-associated V beta 8.2+ sequences can still be found in both peptide-treated and peptide-protected rats. It appears that administration of V beta 8.2 CDR2 peptide does not prevent EAE-associated V beta 8.2+ T cells from infiltrating the CNS and that other mechanisms are at work to prevent the development of EAE.

Analysis of V beta 8.2 CDR3 sequences from spinal cord T cells of Lewis rats vaccinated or treated with TCR V beta 8.2-39-59 peptide

Experimental autoimmune encephalomyelitis (EAE) in the Lewis rat can be induced with the administration of Gp-BP. This disease appears to be mediated at least in part by V beta 8.2+CD4+T cells, which specifically recognize the BP72-89 encephalitogenic peptide. Treatment or protection with V beta 8.2 CDR2 39-59 peptide can suppress or prevent clinical signs of EAE, presumably through the activation of regulatory T cells. Interestingly, V beta 8.2+ T cells continue to persist in the spinal cord of protected animals, although their appearance in the central nervous system (CNS) is delayed when compared with control animals with EAE. As part of our effort to elucidate the mechanism(s) of peptide protection and therapy, we sought to determine whether the V beta 8.2+ T cells in the spinal cord of protected or treated rats were truly representative of those found in rats with clinical EAE. Therefore, we examined the following CNS samples for the Asp96Ser97 motif, which has been identified previously in V beta 8.2+ BP-specific, encephalitogenic T cell clones: 1) rats protected with V beta 8.2-39-59 peptide, 2) rats treated with V beta 8.2-39-59 peptide, and 3) control rats with EAE. Our findings indicate that EAE-associated V beta 8.2+ sequences can still be found in both peptide-treated and peptide-protected rats. It appears that administration of V beta 8.2 CDR2 peptide does not prevent EAE-associated V beta 8.2+ T cells from infiltrating the CNS and that other mechanisms are at work to prevent the development of EAE.

Studies on T-cell receptors involved in experimental autoimmune encephalomyelitis using the complementary peptide recognition approach

Based upon Blalock's complementary recognition approach, a complementary or antisense peptide (CP) was designed to the experimental autoimmune encephalomyelitis (EAE) epitope peptide, rat myelin basic protein (MBP) peptide 72-82. This peptide (EAE CP) was shown to have some sequence similarities to T-cell receptors (TCR) and MHC II molecules in a sequence homology search. Solid-phase binding assays demonstrated specific and high affinity binding (3 and 4 microM) between the EAE CP and the rat and guinea pig EAE epitope peptides (Rt72-82 and Gp69-82), respectively. This EAE CP was also found to be immunogenic in rats in an ear swelling test for delayed type hypersensitivity (DTH) reactions and an ELISA for antibody responses. However, a rabbit antibody generated to EAE CP was shown to be unable to stain the V beta 8+ EAE susceptible T-cells in immunofluorescence analyses. This EAE CP was also used in attempts to down-regulate EAE and the results showed that prior immunization with EAE CP in complete Freund's adjuvant could not prevent the Lewis rats from developing EAE. Although the data on sense-antisense peptide interaction were positive and the EAE CP was immunogenic, the inability of EAE CP to regulate EAE indicates that the CP approach may not be generally applicable.

Effects of anti-CD4 antibody: enhancement of lymph node PPD-memory T cell response

In vitro incubations of CD4+ T cells with anti-CD4 monoclonal antibody (Mab) demonstrated saturation binding and inhibited both PPD-stimulated proliferation and delayed-type hypersensitivity (DTH) after passive transfer of these cells into naive rats. In comparison, in vivo administration of anti-CD4 Mab into rats, 2 weeks after CFA immunization (PPD priming), saturated CD4 molecules expressed on T lymphocytes and depleted significant percentages of CD4+ T cells from blood, spleen, and lymph nodes, yet failed to cause significant inhibition of PPD-stimulated DTH ear swelling. Only repeated in vivo administration of anti-CD4 Mabs during the CFA/PPD antigen priming caused significant decreases (36 +/- 5%) in PPD-stimulated DTH ear swelling. T cells isolated from the blood and spleen showed insignificant relative decreases in PPD-stimulated proliferation after anti-CD4 treatments. In contrast, PPD-stimulated proliferation of T cells isolated from the draining lymph nodes after anti-CD4 treatments showed dramatic increases in PPD reactivity. PPD stimulation of T cells isolated from the draining lymph nodes of anti-CD4 Mab-treated rats produced relative phenotypic changes in CD4 coexpressions with CD45RC (inverse memory), CD49d (inflammatory adhesion integrin VLA-4), and OX40 (CD4+ blast), representative of memory CD4+ T cell blasts with reduced capacity for endothelial infiltration. These data demonstrate that depletion of CD4+ T cells by anti-CD4 Mab injections, administered either during or after antigen priming, selectively enhanced memory responses in T lymphocytes in the draining lymph nodes.

Increased severity of experimental autoimmune encephalomyelitis in rats tolerized as adults but not neonatally to a protective TCR V beta 8 CDR2 idiotope

The ability of synthetic V region peptides to induce regulatory T cells and Abs in rodents and humans provides clear evidence that these idiotopes do not naturally induce tolerance. In this study, we investigated the ability of TCR V beta 8.2 peptides to experimentally induce specific T cell tolerance, as measured by loss of Ag-specific proliferation and delayed-type hypersensitivity responses, and by increased susceptibility to experimental autoimmune encephalomyelitis (EAE). We found that both neonatal and adult exposure to V beta 8.2-39-59 or V beta 8-44-54 peptides could induce efficient T cell tolerance, resulting in a significant inhibition of peptide-specific proliferative responses. In addition, neonatal tolerance resulted in a partial reduction in delayed-type hypersensitivity response and an inability to vaccinate against EAE after adult immunization with the tolerizing peptide. We further evaluated the contribution of naturally induced TCR-specific responses to EAE resistance induced by challenging neonatally or adult tolerized rats with myelin basic protein in adjuvant. The clinical course of EAE was not significantly altered in rats tolerized neonatally to V beta 8.2 peptides, but both the severity and incidence of mortality from EAE was increased in rats tolerized as adults with V beta 8.2 peptides conjugated to syngeneic splenocytes. These results demonstrate that V beta 8.2 peptides are tolerogenic as well as immunogenic. Moreover, the observation of different effects of neonatal vs adult tolerization on the course of EAE suggests either the emergence of additional protective idiotopes after neonatal tolerization and/or mechanistic differences in the two tolerance-inducing protocols. Most importantly, the enhancement of clinical EAE in rats tolerized as adults with V beta 8.2 peptides provides evidence for an innate regulatory role of the CDR2 idiotope in recovery from EAE.

Increased severity of experimental autoimmune encephalomyelitis in rats tolerized as adults but not neonatally to a protective TCR V beta 8 CDR2 idiotope

The ability of synthetic V region peptides to induce regulatory T cells and Abs in rodents and humans provides clear evidence that these idiotopes do not naturally induce tolerance. In this study, we investigated the ability of TCR V beta 8.2 peptides to experimentally induce specific T cell tolerance, as measured by loss of Ag-specific proliferation and delayed-type hypersensitivity responses, and by increased susceptibility to experimental autoimmune encephalomyelitis (EAE). We found that both neonatal and adult exposure to V beta 8.2-39-59 or V beta 8-44-54 peptides could induce efficient T cell tolerance, resulting in a significant inhibition of peptide-specific proliferative responses. In addition, neonatal tolerance resulted in a partial reduction in delayed-type hypersensitivity response and an inability to vaccinate against EAE after adult immunization with the tolerizing peptide. We further evaluated the contribution of naturally induced TCR-specific responses to EAE resistance induced by challenging neonatally or adult tolerized rats with myelin basic protein in adjuvant. The clinical course of EAE was not significantly altered in rats tolerized neonatally to V beta 8.2 peptides, but both the severity and incidence of mortality from EAE was increased in rats tolerized as adults with V beta 8.2 peptides conjugated to syngeneic splenocytes. These results demonstrate that V beta 8.2 peptides are tolerogenic as well as immunogenic. Moreover, the observation of different effects of neonatal vs adult tolerization on the course of EAE suggests either the emergence of additional protective idiotopes after neonatal tolerization and/or mechanistic differences in the two tolerance-inducing protocols. Most importantly, the enhancement of clinical EAE in rats tolerized as adults with V beta 8.2 peptides provides evidence for an innate regulatory role of the CDR2 idiotope in recovery from EAE.

Coculture of TCR peptide-specific T cells with basic protein-specific T cells inhibits proliferation, IL-3 mRNA, and transfer of experimental autoimmune encephalomyelitis

TCR peptides, namely V beta 8.2-39-59 or the minimal idiotope, V beta 8-44-54, can treat experimental autoimmune encephalomyelitis (EAE) in Lewis rats, presumably by activating naturally induced TCR peptide-specific T cells that arise in response to the focused appearance of V beta 8.2+ encephalitogenic T cells. The purpose of the present study was to evaluate the mechanisms by which TCR peptides inhibit EAE. We found that treatment of EAE with the V beta 8.2-39-59 peptide did not induce any evidence of DNA fragmentation (apoptosis) in spinal cord cells isolated from clinically well rats, implicating a regulatory rather than a deletional mechanism. TCR peptide-specific T cell lines failed to inhibit EAE induced by already activated BP-specific T cells when the two T cell specificities were co-injected. However, coculturing the encephalitogenic T cells in the presence of the regulatory T cells during the activation step before transfer almost completely inhibited the induction of EAE. Inhibition could be induced by direct contact between the two cell types or by soluble factors produced in a transwell system, but was greatly enhanced when soluble V beta 8.2-39-59 peptide was used to optimally activate the regulatory T cells. The inhibition was regulatory cell dose dependent, and was reflected in vitro by reduced proliferation response and mRNA production for IL-3, and to a lesser extent, IFN-gamma and IL-2. These results indicate that regulation induced by TCR peptides involves cell-cell interactions that lead to the production and release of soluble factors that locally inhibit the activation of encephalitogenic T cells expressing MHC-bound idiotopes of the target V beta-chain, and possibly "bystander" specificities expressing different V beta-chains.

Coculture of TCR peptide-specific T cells with basic protein-specific T cells inhibits proliferation, IL-3 mRNA, and transfer of experimental autoimmune encephalomyelitis

TCR peptides, namely V beta 8.2-39-59 or the minimal idiotope, V beta 8-44-54, can treat experimental autoimmune encephalomyelitis (EAE) in Lewis rats, presumably by activating naturally induced TCR peptide-specific T cells that arise in response to the focused appearance of V beta 8.2+ encephalitogenic T cells. The purpose of the present study was to evaluate the mechanisms by which TCR peptides inhibit EAE. We found that treatment of EAE with the V beta 8.2-39-59 peptide did not induce any evidence of DNA fragmentation (apoptosis) in spinal cord cells isolated from clinically well rats, implicating a regulatory rather than a deletional mechanism. TCR peptide-specific T cell lines failed to inhibit EAE induced by already activated BP-specific T cells when the two T cell specificities were co-injected. However, coculturing the encephalitogenic T cells in the presence of the regulatory T cells during the activation step before transfer almost completely inhibited the induction of EAE. Inhibition could be induced by direct contact between the two cell types or by soluble factors produced in a transwell system, but was greatly enhanced when soluble V beta 8.2-39-59 peptide was used to optimally activate the regulatory T cells. The inhibition was regulatory cell dose dependent, and was reflected in vitro by reduced proliferation response and mRNA production for IL-3, and to a lesser extent, IFN-gamma and IL-2. These results indicate that regulation induced by TCR peptides involves cell-cell interactions that lead to the production and release of soluble factors that locally inhibit the activation of encephalitogenic T cells expressing MHC-bound idiotopes of the target V beta-chain, and possibly "bystander" specificities expressing different V beta-chains.

Definition of encephalitogenic and immunodominant epitopes of guinea pig myelin basic protein (Gp-BP) in Lewis rats tolerized neonatally with Gp-BP or Gp-BP peptides

Two distinct epitopes of guinea pig basic protein (Gp-BP), residues 72-89 and 87-99, possess encephalitogenic activity in Lewis rats. The purpose of this study was to determine to what degree the 87-99 epitope functions in rats that have been injected with whole Gp-BP, and whether additional epitopes in Gp-BP are encephalitogenic. To address these questions, we induced neonatal tolerance to the dominant synthetic (S)72-89 peptide or to the combination of both S72-89 and S87-99 peptides, and evaluated resistance to experimental autoimmune encephalomyelitis (EAE) induced by Gp-BP, as well as T cell responses to peptides that encompassed most of the Gp-BP molecule. The results demonstrated that virtually all of the encephalitogenic activity of Gp-BP resides within the two described encephalitogenic epitopes. Moreover, deletion of responses to the dominant epitopes prompted T cell responses to other nonencephalitogenic epitopes of Gp-BP, a pattern of response observed previously in rats that had recovered from EAE and in those protected from EAE by vaccination with TCR peptides. These data may have relevance to human autoimmune diseases such as multiple sclerosis in that naturally or immunologically regulated responses to dominant epitopes that are likely to be encephalitogenic may be obscured by increased responses to relatively innocuous determinants of basic protein. Elevated responses to potentially pathogenic autoantigens will likely involve both types of determinants, thus, underscoring the importance of distinguishing encephalitogenic from nonencephalitogenic determinants.

Definition of encephalitogenic and immunodominant epitopes of guinea pig myelin basic protein (Gp-BP) in Lewis rats tolerized neonatally with Gp-BP or Gp-BP peptides

Two distinct epitopes of guinea pig basic protein (Gp-BP), residues 72-89 and 87-99, possess encephalitogenic activity in Lewis rats. The purpose of this study was to determine to what degree the 87-99 epitope functions in rats that have been injected with whole Gp-BP, and whether additional epitopes in Gp-BP are encephalitogenic. To address these questions, we induced neonatal tolerance to the dominant synthetic (S)72-89 peptide or to the combination of both S72-89 and S87-99 peptides, and evaluated resistance to experimental autoimmune encephalomyelitis (EAE) induced by Gp-BP, as well as T cell responses to peptides that encompassed most of the Gp-BP molecule. The results demonstrated that virtually all of the encephalitogenic activity of Gp-BP resides within the two described encephalitogenic epitopes. Moreover, deletion of responses to the dominant epitopes prompted T cell responses to other nonencephalitogenic epitopes of Gp-BP, a pattern of response observed previously in rats that had recovered from EAE and in those protected from EAE by vaccination with TCR peptides. These data may have relevance to human autoimmune diseases such as multiple sclerosis in that naturally or immunologically regulated responses to dominant epitopes that are likely to be encephalitogenic may be obscured by increased responses to relatively innocuous determinants of basic protein. Elevated responses to potentially pathogenic autoantigens will likely involve both types of determinants, thus, underscoring the importance of distinguishing encephalitogenic from nonencephalitogenic determinants.

Analysis of V beta 8-CDR3 sequences derived from central nervous system of Lewis rats with experimental autoimmune encephalomyelitis

We have recently demonstrated that a strong bias for expression of V beta 8.2 is manifested early during the onset of experimental autoimmune encephalomyelitis (EAE) induced by guinea pig basic protein (Gp-BP) immunization of Lewis rats. More importantly, the V beta 8.2 bias was observed in T cells infiltrating the spinal cord (SC) and in cerebrospinal fluid (CSF), but was not present in T cells isolated from the periphery. Here, we report the V beta 8-CDR3 sequences found in unselected SC, CSF, and lymph node (LN) T cell populations at onset of Gp-BP-induced EAE. Striking similarities were observed among sequences derived from SC and CSF. Evidence for oligoclonal expansion of V beta 8.2 sequences associated with previously characterized encephalitogenic clones was observed in both SC and CSF, but not in LN. An AspSer CDR3 motif identified in encephalitogenic clones recognizing the dominant 72-89 epitope of Gp-BP was found in 9/22 SC cDNA clones, 11/24 CSF cDNA clones, and 1/16 LN cDNA clones. Interestingly, J beta 2.7 and J beta 1.3 were also highly represented in SC and CSF, but not in LN. Given that these sequences were derived from T cells present at the site of autoimmune attack and not selected by in vitro manipulation, the data offer compelling evidence that 1) selective recruitment and/or expansion of V beta 8.2+ T cells are occurring in the central nervous system; 2) these events are at least partially dependent on V beta residues which are likely to influence Ag binding; and 3) CSF-derived T cells provide a representative view of CNS events at the onset of EAE.

Analysis of V beta 8-CDR3 sequences derived from central nervous system of Lewis rats with experimental autoimmune encephalomyelitis

We have recently demonstrated that a strong bias for expression of V beta 8.2 is manifested early during the onset of experimental autoimmune encephalomyelitis (EAE) induced by guinea pig basic protein (Gp-BP) immunization of Lewis rats. More importantly, the V beta 8.2 bias was observed in T cells infiltrating the spinal cord (SC) and in cerebrospinal fluid (CSF), but was not present in T cells isolated from the periphery. Here, we report the V beta 8-CDR3 sequences found in unselected SC, CSF, and lymph node (LN) T cell populations at onset of Gp-BP-induced EAE. Striking similarities were observed among sequences derived from SC and CSF. Evidence for oligoclonal expansion of V beta 8.2 sequences associated with previously characterized encephalitogenic clones was observed in both SC and CSF, but not in LN. An AspSer CDR3 motif identified in encephalitogenic clones recognizing the dominant 72-89 epitope of Gp-BP was found in 9/22 SC cDNA clones, 11/24 CSF cDNA clones, and 1/16 LN cDNA clones. Interestingly, J beta 2.7 and J beta 1.3 were also highly represented in SC and CSF, but not in LN. Given that these sequences were derived from T cells present at the site of autoimmune attack and not selected by in vitro manipulation, the data offer compelling evidence that 1) selective recruitment and/or expansion of V beta 8.2+ T cells are occurring in the central nervous system; 2) these events are at least partially dependent on V beta residues which are likely to influence Ag binding; and 3) CSF-derived T cells provide a representative view of CNS events at the onset of EAE.

Immunity to T cell receptor peptides: theory and applications

In this review, we describe an anti-idiotypic regulatory mechanism that is naturally induced by the autoimmune disease process, and that can be boosted by injection of TCR peptides that mimic epitopes generated naturally from germline sequences. The striking similarities in the induction and characteristics of rodent and human T cells specific for TCR peptides support the generality of the observation, and enhance the probability that this immunoregulatory mechanism will have application in human organ-specific autoimmune diseases that are characterized by oligoclonal expression of TCR V genes. The major challenges that remain to be resolved to make the TCR peptide therapy more widely applicable include (1) establishing disease-relevant V gene biases in individual patients, (2) identifying biologically active TCR peptide sequences, and (3) demonstrating that the induction of anti-TCR peptide immunity in humans can reduce the pernicious activity of autoreactive T cells putatively directed at organ-specific target antigens.

Understanding the CD4 molecule: surface expression and function

Surface expression of the CD4 glycoprotein molecule is postulated to facilitate antigen recognition through the T cell receptor (TCR) and is itself a receptor for human immunodeficiency virus (HIV)-gp120 glycoprotein. Both antigen-stimulated TCR activation and HIV infectivity can be blocked by whole anti-CD4 antibodies. Although selective modulation of CD4 from the surface by gangliosides (GM1) blocks HIV infectivity, it enhances associated TCR function. Enhanced TCR function has also been observed after intracellular delivery of synthetic CD4 mRNA-antisense oligodeoxynucleotides (ODN) that block de novo synthesis of CD4. These specific CD4 modulations were mechanistically different from one another yet they both selectively removed the CD4 molecule from the T cell surface and enhanced antigen-stimulated function through the TCR. The proposed role of CD4 during TCR function and HIV infectivity was developed, in part, according to decreases following CD4 antagonism by whole antibody or down-modulation of CD4 by phorbol-stimulated protein kinase C activity. Selective CD4 modulations have independently redefined the specific contributions of CD4 surface expression during T cell activation and may establish a role for CD4 receptor subtypes during HIV-1 infection of CD4+ cells.

Target organ-specific up-regulation of the MRC OX-40 marker and selective production of Th1 lymphokine mRNA by encephalitogenic T helper cells isolated from the spinal cord of rats with experimental autoimmune encephalomyelitis

Lewis x Buffalo F1 rat lymphocytes express both forms of the allelic marker RT7.1 (Lewis) and RT7.2 (Buffalo). We generated myelin basic protein (MBP)-specific encephalitogenic F1 T helper cell lines and adoptively transferred them into naive irradiated Lewis recipients, which enabled us to detect and isolate donor T cells (with RT7.2) within the recipients. The spinal cord and cerebrospinal fluid (CSF) were highly enriched for the donor T cells compared with the blood and spleen. The donor cell number peaked on the first day of disease in the spinal cord and CSF and decreased as the disease progressed. A high percentage of the donor T cells isolated from the spinal cord were positive for the T helper cell activation marker OX-40, whereas a (lower) percentage of CSF donor cells expressed OX-40. Donor cells isolated from blood or spleen were negative for OX-40 expression. In contrast, the IL-2 receptor (CD25) was positive on all the transferred T cells in all tissue sites examined. Cell-sorting experiments showed that the MBP-specific donor cells were enriched for IFN-gamma, IL-2, TNF-alpha, and IL-3 mRNA when compared with the host-recruited spinal cord cells, whereas similar amounts of IL-10 mRNA were produced by both populations. Lymphokine mRNA production was also enriched in donor T cells isolated from the spinal cord compared with donor T cells isolated from the spleen. The spinal cord donor cells produced higher levels of IL-2, IFN-gamma, and IL-3 mRNA, whereas similar amounts of IL-10 and TNF-alpha mRNA were produced from donor cells isolated from the spleen and the spinal cord. Our data suggest that the amount/percentage, activation state, and enhanced lymphokine production at the site of inflammation are all important factors in determining the autoimmune potential of Ag-specific effector T helper cells.

Target organ-specific up-regulation of the MRC OX-40 marker and selective production of Th1 lymphokine mRNA by encephalitogenic T helper cells isolated from the spinal cord of rats with experimental autoimmune encephalomyelitis

Lewis x Buffalo F1 rat lymphocytes express both forms of the allelic marker RT7.1 (Lewis) and RT7.2 (Buffalo). We generated myelin basic protein (MBP)-specific encephalitogenic F1 T helper cell lines and adoptively transferred them into naive irradiated Lewis recipients, which enabled us to detect and isolate donor T cells (with RT7.2) within the recipients. The spinal cord and cerebrospinal fluid (CSF) were highly enriched for the donor T cells compared with the blood and spleen. The donor cell number peaked on the first day of disease in the spinal cord and CSF and decreased as the disease progressed. A high percentage of the donor T cells isolated from the spinal cord were positive for the T helper cell activation marker OX-40, whereas a (lower) percentage of CSF donor cells expressed OX-40. Donor cells isolated from blood or spleen were negative for OX-40 expression. In contrast, the IL-2 receptor (CD25) was positive on all the transferred T cells in all tissue sites examined. Cell-sorting experiments showed that the MBP-specific donor cells were enriched for IFN-gamma, IL-2, TNF-alpha, and IL-3 mRNA when compared with the host-recruited spinal cord cells, whereas similar amounts of IL-10 mRNA were produced by both populations. Lymphokine mRNA production was also enriched in donor T cells isolated from the spinal cord compared with donor T cells isolated from the spleen. The spinal cord donor cells produced higher levels of IL-2, IFN-gamma, and IL-3 mRNA, whereas similar amounts of IL-10 and TNF-alpha mRNA were produced from donor cells isolated from the spleen and the spinal cord. Our data suggest that the amount/percentage, activation state, and enhanced lymphokine production at the site of inflammation are all important factors in determining the autoimmune potential of Ag-specific effector T helper cells.

Immunity to TCR peptides in multiple sclerosis. II. T cell recognition of V beta 5.2 and V beta 6.1 CDR2 peptides

The biased expression of V beta 5.2 and V beta 6.1 by T cells specific for myelin basic protein (BP) has led to our use of TCR peptides from these V gene sequences to induce anti-TCR immunity in patients with multiple sclerosis (MS). Injection of V beta 5.2-39-59 or V beta 6.1-39-59 peptides significantly increased the peptide specific T cell frequency in 7 of 11 MS patients, often with an accompanying delayed hypersensitivity reaction at the injection site. Here, we validate these cellular immune responses by characterizing TCR peptide specific T cells from an MS patient with biased V beta 5.2 expression in BP reactive T cells before treatment with TCR peptides, and from two MS patients in whom the frequencies of anti-TCR peptide specific T cells were significantly boosted after injection with low doses of TCR peptides. In both cases, T cell lines were established with relative ease, especially after boosting with the peptides. A V beta 5.2-39-59 reactive line responded selectively to the boosting peptide and was restricted by both MHC class I (HLA-B7) and MHC class II (HLA-DR2) molecules. Characterization of 22 clonal isolates revealed that the responding T cells were predominantly activated CD4+CD8lo, circulating memory cells restricted by either HLA-B7 or HLA-DR2, that utilized mainly V beta 4, V beta 6, V beta 12, and V beta 14, but not V beta 5.2 in their TCR. T cell isolates specific for V beta 6.1-39-59 possessed similar characteristics but contained specificities cross-reactive with an N-terminal sequence on V beta 5.2-39-59. Upon stimulation with peptide or Con A, the TCR peptide specific T cell lines had increased message production for IFN-gamma, GM-CSF, IL-4, IL-5, and to a lesser degree, IL-2. This lymphokine mRNA profile differed from a BP-specific T cell line that produced message for IFN-gamma and GM-CSF but low or absent levels of IL-4 and IL-5. The extensive parallels between human T cells specific for V beta 5.2 and V beta 6.1 CDR2 peptides and rat T cells specific for V beta 8.2 CDR2 peptide that are highly protective against experimental encephalomyelitis strengthen the rationale for the therapeutic use of TCR peptides in human autoimmunity.

Immunity to TCR peptides in multiple sclerosis. I. Successful immunization of patients with synthetic V beta 5.2 and V beta 6.1 CDR2 peptides

Immunization with disease-associated TCR V region peptides is an effective treatment for experimental autoimmune encephalomyelitis. Myelin basic protein-specific T cells, which induce experimental autoimmune encephalomyelitis in many animal strains, may be important in the pathogenesis of multiple sclerosis. Myelin basic protein-specific T cell clones from some multiple sclerosis patients preferentially use TCR V genes from the V beta 5.2 and V beta 6.1 families. To assess the safety and immunogenicity of TCR V beta 5.2 and V beta 6.1 peptides, we injected 11 multiple sclerosis patients with varying doses of two synthetic peptides, TCR V beta 5.2(39-59) and V beta 6.1(39-59), encompassing the CDR2 region of these V gene families. Low doses (100 to 300 micrograms) of peptide induced T cell immunity in 7 of 11 patients to one or both peptides. Delayed type hypersensitivity skin responses to the peptides were observed in three of seven responders, and TCR peptide-specific Ab occurred in two of seven T cell responders. Low doses of TCR peptides produced no side effects and did not cause broad spectrum immunosuppression. Synthetic TCR V region peptides can induce T cell immunity safely in humans and may prove useful in treating human autoimmune diseases.

Immunity to TCR peptides in multiple sclerosis. I. Successful immunization of patients with synthetic V beta 5.2 and V beta 6.1 CDR2 peptides

Immunization with disease-associated TCR V region peptides is an effective treatment for experimental autoimmune encephalomyelitis. Myelin basic protein-specific T cells, which induce experimental autoimmune encephalomyelitis in many animal strains, may be important in the pathogenesis of multiple sclerosis. Myelin basic protein-specific T cell clones from some multiple sclerosis patients preferentially use TCR V genes from the V beta 5.2 and V beta 6.1 families. To assess the safety and immunogenicity of TCR V beta 5.2 and V beta 6.1 peptides, we injected 11 multiple sclerosis patients with varying doses of two synthetic peptides, TCR V beta 5.2(39-59) and V beta 6.1(39-59), encompassing the CDR2 region of these V gene families. Low doses (100 to 300 micrograms) of peptide induced T cell immunity in 7 of 11 patients to one or both peptides. Delayed type hypersensitivity skin responses to the peptides were observed in three of seven responders, and TCR peptide-specific Ab occurred in two of seven T cell responders. Low doses of TCR peptides produced no side effects and did not cause broad spectrum immunosuppression. Synthetic TCR V region peptides can induce T cell immunity safely in humans and may prove useful in treating human autoimmune diseases.

Immunity to TCR peptides in multiple sclerosis. II. T cell recognition of V beta 5.2 and V beta 6.1 CDR2 peptides

The biased expression of V beta 5.2 and V beta 6.1 by T cells specific for myelin basic protein (BP) has led to our use of TCR peptides from these V gene sequences to induce anti-TCR immunity in patients with multiple sclerosis (MS). Injection of V beta 5.2-39-59 or V beta 6.1-39-59 peptides significantly increased the peptide specific T cell frequency in 7 of 11 MS patients, often with an accompanying delayed hypersensitivity reaction at the injection site. Here, we validate these cellular immune responses by characterizing TCR peptide specific T cells from an MS patient with biased V beta 5.2 expression in BP reactive T cells before treatment with TCR peptides, and from two MS patients in whom the frequencies of anti-TCR peptide specific T cells were significantly boosted after injection with low doses of TCR peptides. In both cases, T cell lines were established with relative ease, especially after boosting with the peptides. A V beta 5.2-39-59 reactive line responded selectively to the boosting peptide and was restricted by both MHC class I (HLA-B7) and MHC class II (HLA-DR2) molecules. Characterization of 22 clonal isolates revealed that the responding T cells were predominantly activated CD4+CD8lo, circulating memory cells restricted by either HLA-B7 or HLA-DR2, that utilized mainly V beta 4, V beta 6, V beta 12, and V beta 14, but not V beta 5.2 in their TCR. T cell isolates specific for V beta 6.1-39-59 possessed similar characteristics but contained specificities cross-reactive with an N-terminal sequence on V beta 5.2-39-59. Upon stimulation with peptide or Con A, the TCR peptide specific T cell lines had increased message production for IFN-gamma, GM-CSF, IL-4, IL-5, and to a lesser degree, IL-2. This lymphokine mRNA profile differed from a BP-specific T cell line that produced message for IFN-gamma and GM-CSF but low or absent levels of IL-4 and IL-5. The extensive parallels between human T cells specific for V beta 5.2 and V beta 6.1 CDR2 peptides and rat T cells specific for V beta 8.2 CDR2 peptide that are highly protective against experimental encephalomyelitis strengthen the rationale for the therapeutic use of TCR peptides in human autoimmunity.

Enhanced T-helper cell function following CD4 modulation

T cells made CD4- by ganglioside (GM1) treatment were cultured in antisense oligodeoxynucleotides complementary to mRNA for CD4. Antisense treatments decreased CD4 levels by 45% but did not prolong the total CD4 modulation by GM1 pretreatment. Northern blot analysis demonstrated that CD4 message production did not change after ganglioside modulation and consequently that it was different from antisense CD4 modulation. However, modulation of CD4 from the cell surface by either GM1 or antisense resulted in greater proliferation and enhanced DTH when challenged with recall antigen. These results demonstrate that selective decrease of CD4 increased antigen-specific T cell responses.

The effect of TCR V beta 8 peptide protection and therapy on T cell populations isolated from the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis

Vaccination or treatment of Lewis rats with TCR V beta 8 peptides can prevent or reverse the clinical signs of experimental autoimmune encephalomyelitis (EAE) which is mediated predominantly by V beta 8.2+ CD4+/CD45R lo T cells. However, rats protected or treated with V beta 8 peptides still developed histological lesions in the spinal cord (SC), even though they remained clinically well. We sought to discern phenotypic changes characteristic of these SC infiltrating lymphocytes. In particular, we focused on whether the immunoregulatory mechanism induced by TCR peptides caused a reduction of V beta 8.2+ T cells, or induced changes in CD45R lo or hi/CD4+ subpopulations that have been associated respectively with EAE induction or recovery. In the V beta 8 peptide vaccinated rats there was a dramatic decrease in the number of V beta 8.2+ T cells isolated from the SC early in disease. During the recovery phase, however, the number of V beta 8.2+ SC T cells was similar in protected and control groups; in contrast, there was striking reduction in the number and size of CD45R hi/CD4+ T cells in the protected animals. In rats treated with V beta 8.2 peptide, no changes were observed in the number of SC V beta 8.2+ T cells or expression of V beta 8.2 message, but similar to vaccinated rats, there was a marked decrease in the number of CD45R hi/CD4+ T cells. These data suggest that vaccination with TCR peptides prevented the initial influx of encephalitogenic V beta 8.2+ T cells into the central nervous system (CNS), whereas treatment appeared to inactivate V beta 8.2+ T cells already present in the CNS. In both cases, TCR peptide-induced inhibition of the encephalitogenic T cells apparently preempted the need for CD45R hi/CD4+ T cells that may normally be necessary to resolve the disease.

Human myelin basic protein (MBP) epitopes recognized by mouse MBP-selected T cell lines from multiple sclerosis patients

We investigated whether myelin basic protein (MBP)-reactive T cells from multiple sclerosis (MS) patients can recognize mouse MBP since this is an expected requirement for the transfer of experimental autoimmune encephalomyelitis (EAE) into severe combined immunodeficiency (SCID) mouse-human chimeras. Peripheral blood mononuclear cells from 11 MS patients were analyzed for in vitro proliferation to mouse MBP. Six patients (55%) responded to mouse MBP at the first or second stimulation. Five T cell lines, selected with mouse MBP from five MS patients, were analyzed for their proliferation to mouse and human MBP and to a panel of synthetic peptides of human MBP. Four of the five lines recognized mouse MBP. In vitro proliferation was restricted by MHC class II in one line tested for MHC restriction. One of the five lines recognized whole human MBP and all five of the lines responded to at least one of the five synthetic peptides corresponding to human MBP residues 8-28, 67-90, 84-102, 87-99 or 130-149. These results show that MS patient T cells recognize mouse MBP and suggest that distinct human MBP epitopes are immunologically cross-reactive with epitopes of mouse MBP.

Lymphokine mRNA expression in the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis is associated with a host recruited CD45R hi/CD4+ population during recovery

To evaluate CD4+ T cell subpopulations involved in the induction and recovery from experimental autoimmune encephalomyelitis (EAE), the CD45R phenotype and lymphokine mRNA profile was evaluated for encephalitogenic CD4+ T cell lines in vitro and compared to CD4+ T cells isolated from the spinal cord of Lewis rats with EAE. All of the myelin basic protein (MBP)-specific T cell lines and clones that adoptively transferred EAE were > 90% CD4+ and > 90% CD45R lo. A time course of EAE disease progression was monitored as a function of the percentage of CD45R hi/CD4+ T cells isolated from the spinal cords of diseased animals. The majority of CD4+ T cells found in the central nervous system during the early phase of passive EAE were CD45R lo (the same as the encephalitogenic lines/clones). A large increase of the CD45R hi/CD4+ T cells (up to 45%) was observed during the peak and recovery phases of EAE. Lymphokine mRNA production was analyzed from antigen-stimulated MBP-specific lines, and from spinal cord lymphocytes isolated from rats with EAE. The BP-specific lines produced Th1 lymphokines (IL-2, IFN-gamma, and TNF-alpha), while the spinal cord lymphocytes produced the same Th1 lymphokines as well as IL-4 and IL-10. The CD45R hi/CD4+ T cells isolated from the spinal cords were larger and expressed more lymphokine RNA per cell than the CD45R lo/CD4+ T cells. The encephalitogenic cells (CD45R lo) were detected in the spinal cords of rats with a fluorescent dye and by allelic transfers and all of the CD45R hi/CD4+ T cells were found to be host recruited. Thus, it appears that the CD45R hi/CD4+ lymphocytes found in the spinal cord represent a host-recruited, activated cellular infiltrate that increased in number in the recovery phase of EAE and synthesized both Th1 and Th2 lymphokines.

Where, when, and how to detect biased expression of disease-relevant V beta genes in rats with experimental autoimmune encephalomyelitis

The biased use of V beta 8.2 and V beta 6 in rats by encephalitogenic T cells specific for the S72-89 and S87-99 epitopes of guinea pig basic protein (Gp-BP) has allowed the use of anti-V beta antibodies and synthetic TCR peptides for treatment of experimental autoimmune encephalomyelitis (EAE). Striking V gene biases also occur in human autoimmune diseases, raising the question of to what degree these biases reflect potentially pathogenic T cells. To address this question, we evaluated the expression of the EAE-associated marker V beta 8.2 and V beta 6 molecules in the periphery, spinal cord (SC), and cerebrospinal fluid (CSF) during the course of EAE, in unselected, IL-2-expanded, and Gp-BP-restimulated populations. In CSF cells, there was a strong bias for the marker V beta before the onset of EAE, but this bias was not enhanced by IL-2, which skewed the CSF population to > 80% CD8+ T cells. In SC, the marker V beta were expressed optimally during the onset of EAE, even in unselected cells, and this bias could be enhanced sequentially by IL-2 expansion and Gp-BP restimulation. During the recovery phase, however, the marker V beta 8.2 bias was obfuscated by the appearance of a heterogeneous V beta T cell population. Biased expression of the marker V genes was not detected in unselected or IL-2-expanded peripheral cells at any time during EAE. These data suggest that peripheral T cells bearing the disease-relevant V genes first appeared in CSF before disease onset and then migrated to SC beginning on the first day of clinical signs. During the recovery phase of the disease, these cells were diluted by an influx of T cells bearing other V beta genes, requiring restimulation with Gp-BP to observe the V beta 8.2 bias. These data have important implications for the interpretation of V beta gene biases that have been reported in human autoimmune diseases.

Where, when, and how to detect biased expression of disease-relevant V beta genes in rats with experimental autoimmune encephalomyelitis

The biased use of V beta 8.2 and V beta 6 in rats by encephalitogenic T cells specific for the S72-89 and S87-99 epitopes of guinea pig basic protein (Gp-BP) has allowed the use of anti-V beta antibodies and synthetic TCR peptides for treatment of experimental autoimmune encephalomyelitis (EAE). Striking V gene biases also occur in human autoimmune diseases, raising the question of to what degree these biases reflect potentially pathogenic T cells. To address this question, we evaluated the expression of the EAE-associated marker V beta 8.2 and V beta 6 molecules in the periphery, spinal cord (SC), and cerebrospinal fluid (CSF) during the course of EAE, in unselected, IL-2-expanded, and Gp-BP-restimulated populations. In CSF cells, there was a strong bias for the marker V beta before the onset of EAE, but this bias was not enhanced by IL-2, which skewed the CSF population to > 80% CD8+ T cells. In SC, the marker V beta were expressed optimally during the onset of EAE, even in unselected cells, and this bias could be enhanced sequentially by IL-2 expansion and Gp-BP restimulation. During the recovery phase, however, the marker V beta 8.2 bias was obfuscated by the appearance of a heterogeneous V beta T cell population. Biased expression of the marker V genes was not detected in unselected or IL-2-expanded peripheral cells at any time during EAE. These data suggest that peripheral T cells bearing the disease-relevant V genes first appeared in CSF before disease onset and then migrated to SC beginning on the first day of clinical signs. During the recovery phase of the disease, these cells were diluted by an influx of T cells bearing other V beta genes, requiring restimulation with Gp-BP to observe the V beta 8.2 bias. These data have important implications for the interpretation of V beta gene biases that have been reported in human autoimmune diseases.

Treatment of relapsing experimental autoimmune encephalomyelitis with T cell receptor peptides

Restricted T cell receptor (TCR) VB gene usage by T cells for recognition of antigens involved in the production of experimental autoimmune encephalomyelitis (EAE) offers the possibility of selective immunotherapy. We determined the preferential VB gene usage of lymph node-derived clones from SJL/J mice to recognize the encephalitogenic epitope PLP 139-151 and from PL/J mice to recognize the newly described encephalitogenic epitope PLP 43-64. In addition, the VB gene usage for recognition of PLP 139-151 by T cell lines derived from SJL/J spinal cords was analyzed. Lymph node-derived SJL/J lines and clones specific for PLP 139-151 expressed VB2, VB4, and VB17a preferentially, and PL/J lines and clones specific for PLP 43-64 expressed VB2 and VB8.2 preferentially. A VB4 + SJL/J clone and a VB8.2 + PL/J clone were encephalitogenic. Encephalitogenic SJL/J lines derived from spinal cord expressed VB2, VB10, VB16, and VB17a preferentially, with a predominance of VB2. Candidate TCR peptides were synthesized and tested from the VB gene families VB4, VB8.2, and VB17a, based on our data and previous data on BP-induced EAE in mice. Treatment of relapsing EAE (R-EAE) in SJL/J mice with VB4 and VB17a peptides reduced clinical and histological disease severity, and treatment of R-EAE in (PLxSJL)F1 mice with VB4 and VB8.2 peptides also reduced clinical and histological disease. The use of TCR peptide therapy may have applications for the treatment of human autoimmune diseases such as multiple sclerosis.

Induction of experimental autoimmune encephalomyelitis in severe combined immunodeficient mice reconstituted with allogeneic or xenogeneic hematopoietic cells

Severe combined immunodeficient (SCID) C.B-17-scid/scid (H-2d) strain mice are deficient for T and B lymphocytes and lack all of the immune functions associated with these cell types. Experimental autoimmune encephalomyelitis (EAE) was induced in chimeric SCID mice that had been previously reconstituted with allogeneic mouse or xenogeneic rat hematopoietic stem cells from EAE-susceptible donor strains. Encephalitogenic, myelin Ag-specific, T lymphocytes selected from SJL mice, Lewis rats, or Buffalo rats transferred passive EAE into chimeric SCID mice reconstituted with SJL mouse, Lewis rat, or Buffalo rat hematopoietic cells, respectively. SCID mice reconstituted with Lewis rat hematopoietic tissue and thymus were also susceptible to EAE induced by active immunization with the myelin proteolipid protein synthetic peptide PLP S139-151. T lymphocytes recovered from the spleens of SCID mouse-rat chimeras with EAE proliferated upon in vitro stimulation with myelin Ag presented by APC syngeneic to the transplant donor, and rat T lymphocytes selected in vitro from SCID mouse-rat chimeras with EAE transferred EAE back into naive recipient rats. Thus, the immunodeficiency present in SCID mice can be overcome at least partially by hematopoietic tissue transplantation from allogeneic or xenogeneic donors. Furthermore, allogeneic SJL mouse and xenogeneic Lewis or Buffalo rat myelin Ag-specific T cells can transfer EAE between strains and species, respectively, into recipient SCID mouse chimeras.

Induction of experimental autoimmune encephalomyelitis in severe combined immunodeficient mice reconstituted with allogeneic or xenogeneic hematopoietic cells

Severe combined immunodeficient (SCID) C.B-17-scid/scid (H-2d) strain mice are deficient for T and B lymphocytes and lack all of the immune functions associated with these cell types. Experimental autoimmune encephalomyelitis (EAE) was induced in chimeric SCID mice that had been previously reconstituted with allogeneic mouse or xenogeneic rat hematopoietic stem cells from EAE-susceptible donor strains. Encephalitogenic, myelin Ag-specific, T lymphocytes selected from SJL mice, Lewis rats, or Buffalo rats transferred passive EAE into chimeric SCID mice reconstituted with SJL mouse, Lewis rat, or Buffalo rat hematopoietic cells, respectively. SCID mice reconstituted with Lewis rat hematopoietic tissue and thymus were also susceptible to EAE induced by active immunization with the myelin proteolipid protein synthetic peptide PLP S139-151. T lymphocytes recovered from the spleens of SCID mouse-rat chimeras with EAE proliferated upon in vitro stimulation with myelin Ag presented by APC syngeneic to the transplant donor, and rat T lymphocytes selected in vitro from SCID mouse-rat chimeras with EAE transferred EAE back into naive recipient rats. Thus, the immunodeficiency present in SCID mice can be overcome at least partially by hematopoietic tissue transplantation from allogeneic or xenogeneic donors. Furthermore, allogeneic SJL mouse and xenogeneic Lewis or Buffalo rat myelin Ag-specific T cells can transfer EAE between strains and species, respectively, into recipient SCID mouse chimeras.

Epitope specificity and V gene expression of cerebrospinal fluid T cells specific for intact versus cryptic epitopes of myelin basic protein

Recent evidence supports the possible involvement of myelin basic protein (BP) as one of the target autoantigens in multiple sclerosis (MS), including elevated frequencies of MS blood and cerebrospinal fluid (CSF) T cells, and the presence in MS plaque tissue of V beta gene sequences and CDR3 motifs characteristic of BP-reactive T cells. Because of its proximity to the target organ, the CSF has long been thought to harbor T cells involved in the pathogenic process. In order to evaluate their frequency and response characteristics, BP-reactive T cells were isolated by limiting dilution from the CSF of patients with MS and other neurological diseases (OND) for quantitation and determination of epitope specificity and V alpha and V beta gene expression. In addition to isolates responsive to intact BP epitopes that were present at a significantly higher frequency in MS versus OND CSF, we here describe a second clonotype responsive to 'cryptic' BP epitopes that is present at approximately equal frequencies in MS and OND patients. In spite of their difference in recognition of intact versus 'cryptic' BP determinants, both clonotypes predominantly recognized epitopes in the N terminal half of human BP, using a similar V gene repertoire that included biased use of V alpha 2 and to a lesser degree V beta 7 and V beta 18. These V gene biases were not related to the epitope specificity of the T cells, indicating that V gene selection is not epitope-driven. These data suggest that there is differential recognition of intact versus 'cryptic' BP determinants in MS versus OND patients that may be related to the processing and presentation of BP to the immune system.

T-cell receptor peptide therapy in EAE and MS

Synthetic peptides corresponding to germline TCR V beta 8.2 sequences overexpressed by Lewis rat encephalitogenic T cells are effective in the prevention and treatment of autoimmune encephalomyelitis (EAE). In evaluating optimal conditions for identifying disease-relevant target V beta genes, we found that the biased expression of V beta 8.2 was most pronounced in the CNS among activated, IL-2 responsive T cells, but was weakly reflected in the cerebrospinal fluid. Evaluation of basic protein reactive T cells from patients with multiple sclerosis revealed biased expression of V beta 5.2 and to a lesser degree, V beta 6.1. Treatment of 11 MS patients with synthetic TCR V beta 5.2 and V beta 6.1 CDR2 peptides boosted the frequency of anti-TCR reactive T cells in a majority of patients, without compromising recall immunity or causing side effects. TCR peptides may be useful in the treatment of human autoimmune diseases, providing that disease-relevant V genes can be identified.

Spontaneous development of protective anti-T cell receptor autoimmunity targeted against a natural EAE-regulatory idiotope located within the 39-59 region of the TCR-V beta 8.2 chain

The development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats is mediated by V beta 8.2+ T cells specific for myelin basic protein. One consequence of this biased expression of V beta 8.2 is the spontaneous development of regulatory T cells and antibodies against residues 39-59 of the V beta 8.2 sequence. Moreover, a synthetic V beta 8.2-39-59 peptide could induce protection against and speed recovery from EAE. T cells and antibodies specific for V beta 8.2-39-59 could transfer protection from EAE. Recently, we reported that the protective T cell epitope is subsumed within the V beta 8-44-54 sequence. We now report that protection induced by V beta 8-44-54 lasted at least 102 days and produced "split tolerance," enhancing anti-myelin basic protein antibody titers but reducing anti-myelin basic protein T cell frequency. The shorter V beta 8-44-54 peptide induced a distinct set of antibodies that did not cross-react with the longer V beta 8.2-39-59 peptide, although both specificities could stain V beta 8.2+ T cells and were equally protective against EAE. However, the V beta 8.2-39-59 peptide, but not the V beta 8-44-54 peptide, would appear to represent the natural idiotope: antibodies to V beta 8.2-39-59 that develop spontaneously during EAE could be boosted to higher titers only by the V beta 8.2-39-59, but not by other TCR peptides from the V beta 8.2 sequence, including V beta 8-44-54 that contains the functional T cell epitope. These results suggest that natural processing of the TCR V beta-chain favors the formation of a peptide that resembles the V beta 8.2-39-59 sequence. The B cell epitope present on the V beta 8-44-54 sequence was evident only in the absence of residues 39-43 and 55-59, suggesting that the two peptides possess distinct conformations. However, the V beta 8-44-54 B cell epitope is most likely expressed on the V beta 8.2+ T cells, either as a low affinity determinant on the intact TCR alpha/beta heterodimer or as a cryptic epitope bound in the cleft of surface MHC molecules.

Spontaneous development of protective anti-T cell receptor autoimmunity targeted against a natural EAE-regulatory idiotope located within the 39-59 region of the TCR-V beta 8.2 chain

The development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats is mediated by V beta 8.2+ T cells specific for myelin basic protein. One consequence of this biased expression of V beta 8.2 is the spontaneous development of regulatory T cells and antibodies against residues 39-59 of the V beta 8.2 sequence. Moreover, a synthetic V beta 8.2-39-59 peptide could induce protection against and speed recovery from EAE. T cells and antibodies specific for V beta 8.2-39-59 could transfer protection from EAE. Recently, we reported that the protective T cell epitope is subsumed within the V beta 8-44-54 sequence. We now report that protection induced by V beta 8-44-54 lasted at least 102 days and produced "split tolerance," enhancing anti-myelin basic protein antibody titers but reducing anti-myelin basic protein T cell frequency. The shorter V beta 8-44-54 peptide induced a distinct set of antibodies that did not cross-react with the longer V beta 8.2-39-59 peptide, although both specificities could stain V beta 8.2+ T cells and were equally protective against EAE. However, the V beta 8.2-39-59 peptide, but not the V beta 8-44-54 peptide, would appear to represent the natural idiotope: antibodies to V beta 8.2-39-59 that develop spontaneously during EAE could be boosted to higher titers only by the V beta 8.2-39-59, but not by other TCR peptides from the V beta 8.2 sequence, including V beta 8-44-54 that contains the functional T cell epitope. These results suggest that natural processing of the TCR V beta-chain favors the formation of a peptide that resembles the V beta 8.2-39-59 sequence. The B cell epitope present on the V beta 8-44-54 sequence was evident only in the absence of residues 39-43 and 55-59, suggesting that the two peptides possess distinct conformations. However, the V beta 8-44-54 B cell epitope is most likely expressed on the V beta 8.2+ T cells, either as a low affinity determinant on the intact TCR alpha/beta heterodimer or as a cryptic epitope bound in the cleft of surface MHC molecules.

TCR peptide therapy decreases the frequency of encephalitogenic T cells in the periphery and the central nervous system

The V beta 8 CDR2 consensus peptide, residues 44-54, is highly effective in the treatment of clinical experimental autoimmune encephalomyelitis (EAE) in Lewis rats. To monitor immunological changes during EAE resulting from TCR peptide therapy, the frequencies of encephalitogenic and regulatory T cells were quantitated in lymph nodes, blood, and spinal cord. The frequency of T cells specific for basic protein and its major encephalitogenic epitope, residues 72-89, increased during EAE to about 1 cell per 100,000 lymph node or blood cells at the peak of clinical disease, and then declined. In contrast, the frequency of these T cells in spinal cord was highest, 50 per 100,000, prior to onset of clinical signs, and then decreased rapidly prior to spontaneous recovery. Injection of 100 micrograms of TCR V beta 8-44-54 peptide caused a decrease within 1-5 days in the frequencies of guinea pig basic-protein (GP-BP) and 72-89-reactive T cells in blood and spinal cord, and in the total number of infiltrating cells in spinal cord. In lymph nodes, 72-89-reactive T cells decreased as T cells specific for a protective epitope, residues 55-69 of GP-BP increased, suggesting epitope switching at the site of GP-BP immunization. Conversely, the frequency of T cells specific for the V beta 8-44-54 peptide increased, especially in blood and spinal cord, whereas T cell frequencies to control antigens were unchanged. These data document the critical presence of encephalitogenic T cells within the spinal cord during clinical EAE, and demonstrate that rapid and profound changes in T cell frequencies in the periphery and spinal cord are triggered by TCR peptide therapy.

Frequency of T cells specific for myelin basic protein and myelin proteolipid protein in blood and cerebrospinal fluid in multiple sclerosis

T cell sensitization to two myelin components, myelin basic protein (MBP) and myelin proteolipid protein (PLP), may be important to the pathogenesis of multiple sclerosis (MS). Using the limiting dilution assay, we demonstrated that the blood of MS patients had an increased frequency of MBP-reactive T cells compared with normal subjects and patients with other neurological diseases (OND) and rheumatoid arthritis. There was no difference in T cell frequency to a synthetic peptide, PLP139-151, or Herpes simplex virus. Within cerebrospinal fluid (CSF), 37% of IL-2/IL-4-reactive T cell isolates from MS patients responded either to MBP or PLP139-151 while only 5% of similar isolates from OND patients responded to these myelin antigens. The mean relative frequency of MBP-reactive T cells within CSF from MS patients was significantly higher than that of OND patients (22 x 10(-5) cells versus 1 x 10(-5) cells) and was similar to that of MBP reactive T cells within the central nervous system of rats with experimental autoimmune encephalomyelitis. These results lend new support to the hypothesis that myelin-reactive T cells mediate disease in MS.

T cell receptor peptide therapy for autoimmune disease

Synthetic peptides corresponding to germline T cell receptor (TCR) V beta sequences shared by encephalitogenic T cells can prevent and treat experimental autoimmune encephalomyelitis in rats. The operative mechanism apparently involves boosting of anti-TCR immunity that develops during the course of experimental autoimmune encephalomyelitis (EAE), leading to the induction of autoregulatory T cells and antibodies. Striking parallels are present between patients with multiple sclerosis and animals with EAE in the T cell frequency and TCR V gene bias of BP reactive T cells, suggesting the involvement of an encephalitogenic process in multiple sclerosis. Preliminary trials with the appropriate human TCR peptides indicate that anti-TCR immunity can be boosted efficiently and safely, with concomitant loss of BP response, thus providing an effective strategy for selective regulation of autoimmunity in man.

Transforming growth factor-beta enhances the in vivo effector function and memory phenotype of antigen-specific T helper cells in experimental autoimmune encephalomyelitis

Transforming growth factor-beta (TGF-beta) had a profound effect on the in vitro phenotypic development of Ag-activated Th cells and enhanced the in vivo effector function of these cells upon adoptive transfer. Previous studies have shown that there are two types of Th cell populations found in unimmunized animals, naive helper cells, which are short-lived and express low levels of CD44 and high levels of CD45R and Mel-14, and memory helper cells, which have a long life span and express high levels of CD44 and low levels of CD45R and Mel-14. Culturing of Ag-specific murine Th cell lines and clones in the presence of TGF-beta greatly enhanced both the memory phenotype of the cultured cells and the effector function upon adoptive transfer in experimental autoimmune encephalomyelitis. Histologic evaluation of spinal cords from recipients receiving passively transferred murine T cell lines cultured with TGF-beta revealed large demyelinated plaques (multiple sclerosis-like) that were not present in animals receiving cells cultured with Ag alone. TGF-beta also enhanced the capability of myelin basic protein-specific Lewis rat T cell lines to transfer experimental autoimmune encephalomyelitis and potentiated a purified protein derivative-specific rat helper cell line to transfer delayed type hypersensitivity. Thus, the effects of TGF-beta did not appear to be limited by species specificity, Ag specificity, or in vivo T cell function. This is the first study showing that TGF-beta can potentiate the development and maintenance of the Th cell memory phenotype in vitro and enhance their in vivo effector function in an animal disease model.

Transforming growth factor-beta enhances the in vivo effector function and memory phenotype of antigen-specific T helper cells in experimental autoimmune encephalomyelitis

Transforming growth factor-beta (TGF-beta) had a profound effect on the in vitro phenotypic development of Ag-activated Th cells and enhanced the in vivo effector function of these cells upon adoptive transfer. Previous studies have shown that there are two types of Th cell populations found in unimmunized animals, naive helper cells, which are short-lived and express low levels of CD44 and high levels of CD45R and Mel-14, and memory helper cells, which have a long life span and express high levels of CD44 and low levels of CD45R and Mel-14. Culturing of Ag-specific murine Th cell lines and clones in the presence of TGF-beta greatly enhanced both the memory phenotype of the cultured cells and the effector function upon adoptive transfer in experimental autoimmune encephalomyelitis. Histologic evaluation of spinal cords from recipients receiving passively transferred murine T cell lines cultured with TGF-beta revealed large demyelinated plaques (multiple sclerosis-like) that were not present in animals receiving cells cultured with Ag alone. TGF-beta also enhanced the capability of myelin basic protein-specific Lewis rat T cell lines to transfer experimental autoimmune encephalomyelitis and potentiated a purified protein derivative-specific rat helper cell line to transfer delayed type hypersensitivity. Thus, the effects of TGF-beta did not appear to be limited by species specificity, Ag specificity, or in vivo T cell function. This is the first study showing that TGF-beta can potentiate the development and maintenance of the Th cell memory phenotype in vitro and enhance their in vivo effector function in an animal disease model.

The synthetic 87–99 peptide of myelin basic protein is encephalitogenic in Buffalo rats

A synthetic peptide corresponding to residues 87-99 (S87-99) of myelin basic protein (BP) induced the proliferation of an encephalitogenic, BP-specific T cell line selected in vitro from inbred Buffalo-strain rats (RT1b). Active immunization with guinea pig (GP)-BP or S87-99 in complete Freund's adjuvant (CFA) and intravenous pertussigen induced acute experimental autoimmune encephalomyelitis (EAE) 10-12 days after immunization. Fifty percent of recovered rats developed a single relapse 17-21 days after immunization. T lymphocytes selected in vitro with S87-99 transferred acute, non-relapsing EAE into naive recipients. Histological examination during acute EAE revealed foci of inflammatory cells associated with demyelination in the spinal cords and peripheral nerve roots. Thus, as in several other rodent strains, the 87-99 region of BP is antigenic and encephalitogenic in the inbred Buffalo-strain rat. Additionally, the 87-99 sequence of GP-BP was predicted to be antigenic by two different methods. These results suggest that the 87-99 region of BP, which is highly conserved among mammalian species, may be widely encephalitogenic due to antigen-intrinsic properties.