Characterization of the immune response to a secondary encephalitogenic epitope of basic protein in Lewis rats. II. Biased T cell receptor V beta expression predominates in spinal cord infiltrating T cells

The immune response of Lewis rat lymph node T cells to guinea pig myelin basic protein (GP-BP) in experimental allergic encephalomyelitis is directed primarily against a region of basic protein encompassed by residues 72-89. T cells that respond to this epitope are restricted by the RT1.B class II molecule of the MHC and use V beta 8.2 exclusively in their TCR. A second region of GP-BP, residues 87-99, also induces experimental allergic encephalomyelitis in Lewis rats but this response is restricted primarily by RT1.D. Elsewhere we describe the biologic characteristics of T cell clones responding to the synthetic peptide, s87-99, and to a related peptide, s85-99. We present a detailed analysis of TCR V beta gene expression among these clones, derived from the lymph node and spinal cord of immunized animals, and among spinal cord derived T cell clones reactive to GP-BP 72-89. We find that spinal cord-derived clones, reactive to s85-99 and to s87-99, use V beta 6 predominantly. In contrast, T cell clones derived from lymph nodes and reactive to the same peptides express multiple V beta genes including V beta 6. This difference in heterogeneity of V beta usage at the clonal level is also seen in T cell lines derived from spinal cord and immune lymph node. DNA sequence comparison of the CDR3 regions in V beta 6+ spinal cord clones revealed a conserved amino acid motif also found in the majority of V beta 6 sequences from the spinal cord anti-s85-99 line. Although V beta 6 was expressed in some lymph node-derived clones, only one contained a CDR3 region similar to that seen in spinal cord isolates. All spinal cord-derived T cell clones reactive to GP-BP 72-89 used V beta 8.2 and most (five of six) contained the AspSer residues in CDR3 previously shown to be associated with V beta 8.2 receptors expressed by the majority of lymph node T cells responding to GP-BP 72-89. These data indicate that TCR V beta usage in peripheral T cells responding to an autoantigen does not always predict the V beta usage among T cells at the site of an autoimmune attack. Possible explantations for the relative homogeneity in TCR V beta expression seen in T cell clones derived from the spinal cord are discussed.

Characterization of the immune response to a secondary encephalitogenic epitope of basic protein in Lewis rats. II. Biased T cell receptor V beta expression predominates in spinal cord infiltrating T cells

The immune response of Lewis rat lymph node T cells to guinea pig myelin basic protein (GP-BP) in experimental allergic encephalomyelitis is directed primarily against a region of basic protein encompassed by residues 72-89. T cells that respond to this epitope are restricted by the RT1.B class II molecule of the MHC and use V beta 8.2 exclusively in their TCR. A second region of GP-BP, residues 87-99, also induces experimental allergic encephalomyelitis in Lewis rats but this response is restricted primarily by RT1.D. Elsewhere we describe the biologic characteristics of T cell clones responding to the synthetic peptide, s87-99, and to a related peptide, s85-99. We present a detailed analysis of TCR V beta gene expression among these clones, derived from the lymph node and spinal cord of immunized animals, and among spinal cord derived T cell clones reactive to GP-BP 72-89. We find that spinal cord-derived clones, reactive to s85-99 and to s87-99, use V beta 6 predominantly. In contrast, T cell clones derived from lymph nodes and reactive to the same peptides express multiple V beta genes including V beta 6. This difference in heterogeneity of V beta usage at the clonal level is also seen in T cell lines derived from spinal cord and immune lymph node. DNA sequence comparison of the CDR3 regions in V beta 6+ spinal cord clones revealed a conserved amino acid motif also found in the majority of V beta 6 sequences from the spinal cord anti-s85-99 line. Although V beta 6 was expressed in some lymph node-derived clones, only one contained a CDR3 region similar to that seen in spinal cord isolates. All spinal cord-derived T cell clones reactive to GP-BP 72-89 used V beta 8.2 and most (five of six) contained the AspSer residues in CDR3 previously shown to be associated with V beta 8.2 receptors expressed by the majority of lymph node T cells responding to GP-BP 72-89. These data indicate that TCR V beta usage in peripheral T cells responding to an autoantigen does not always predict the V beta usage among T cells at the site of an autoimmune attack. Possible explantations for the relative homogeneity in TCR V beta expression seen in T cell clones derived from the spinal cord are discussed.

Characterization of the immune response to a secondary encephalitogenic epitope of basic protein in Lewis rats. I. T cell receptor peptide regulation of T cell clones expressing cross-reactive V beta genes

In Lewis rats, immunization with myelin basic protein induces two distinct encephalitogenic T cell populations, those responding to the immunodominant 72-89 epitope and those specific for a secondary epitope including residues 87-99. The 72-89 specific T cells were I-A restricted and preferentially expressed V beta 8.2 in their TCR. To determine the fine specificity, MHC restriction, and TCR V beta gene use in T cells reactive to the secondary epitope, we characterized 23 T cell clones from the lymph nodes (LN) and spinal cords (SC) of rats immunized with either whole basic protein or synthetic peptides S85-99 and S87-99 that were found to be functionally similar. The S85-99/S87-99 specific clones from LN and SC were all encephalitogenic despite differences in recognition of intact basic protein and class II MHC restriction. Unlike LN clones that overexpressed V beta 8 (46%+) and V beta 6 (31%+), however, SC clones were strongly biased (86%+) in their expression of V beta 6. This V gene bias raised the possibility of TCR peptide therapy using V beta 6 peptides. The V beta 6 sequence was similar to V beta 8.2 in the CDR2 region, and the corresponding peptides from this region were found to be cross-reactive in vivo. Moreover, both peptides were effective in the treatment of EAE induced with either S85-99, biased in V beta 6+ and V beta 8+ T cells, or guinea pig basic protein, biased only in V beta 8+ T cells. These data demonstrate the presence of common immunogenic epitopes among subsets of TCR V region gene families that possess important regulatory activity on effector T cell function.

Characterization of the immune response to a secondary encephalitogenic epitope of basic protein in Lewis rats. I. T cell receptor peptide regulation of T cell clones expressing cross-reactive V beta genes

In Lewis rats, immunization with myelin basic protein induces two distinct encephalitogenic T cell populations, those responding to the immunodominant 72-89 epitope and those specific for a secondary epitope including residues 87-99. The 72-89 specific T cells were I-A restricted and preferentially expressed V beta 8.2 in their TCR. To determine the fine specificity, MHC restriction, and TCR V beta gene use in T cells reactive to the secondary epitope, we characterized 23 T cell clones from the lymph nodes (LN) and spinal cords (SC) of rats immunized with either whole basic protein or synthetic peptides S85-99 and S87-99 that were found to be functionally similar. The S85-99/S87-99 specific clones from LN and SC were all encephalitogenic despite differences in recognition of intact basic protein and class II MHC restriction. Unlike LN clones that overexpressed V beta 8 (46%+) and V beta 6 (31%+), however, SC clones were strongly biased (86%+) in their expression of V beta 6. This V gene bias raised the possibility of TCR peptide therapy using V beta 6 peptides. The V beta 6 sequence was similar to V beta 8.2 in the CDR2 region, and the corresponding peptides from this region were found to be cross-reactive in vivo. Moreover, both peptides were effective in the treatment of EAE induced with either S85-99, biased in V beta 6+ and V beta 8+ T cells, or guinea pig basic protein, biased only in V beta 8+ T cells. These data demonstrate the presence of common immunogenic epitopes among subsets of TCR V region gene families that possess important regulatory activity on effector T cell function.

Common sequence on distinct V beta genes defines a protective idiotope in experimental encephalomyelitis

Synthetic TCR peptides expressed by encephalitogenic T cells can induce both cellular and humoral responses that protect against experimental encephalomyelitis. In the Lewis rat, encephalitogenic T cells predominantly express V beta 8.2, and a peptide in the CDR2 region representing residues 39-59 could both protect against and treat experimental autoimmune encephalitis (EAE). Similarly, the homologous and cross reactive 39-59 peptide from V beta 8.6 expressed by an EAE-protective clone also had protective and therapeutic activity against EAE. The consensus sequence between the V beta 8.2 and V beta 8.6 peptides, which included residues 44-54, was postulated to contain the protective idiotope. In this report, we demonstrate that this peptide, designated V beta 8-44-54, has comparable activity to the longer peptides for treating both active and passive EAE. Similar to the longer V beta 8.2-39-59 peptide, the V beta 8-44-54 peptide stimulates protective TCR peptide-specific CD4+, CD8dim T cells restricted by MHC I. We also report for the first time the recovery of V beta 8-44-54 reactive T cells that express a variety of V beta genes in their T-cell receptor (TCR), including V beta 4, 8, 10, 12, 15, 17, 19, and 20. Taken together, these data establish that the V beta 8-44-54 sequence constitutes an important autoregulatory idiotope in EAE.(ABSTRACT TRUNCATED AT 250 WORDS)

Human CD8+ T cell clone regulates autologous CD4+ myelin basic protein specific T cells

Normal human CD8+ T cell clones were co-isolated from the same culture wells as CD4+ T effector cell clones specific for myelin basic protein (MBP). Microcultures from which the CD8+ clones were isolated initially proliferated weakly to whole MBP and to an MBP peptide spanning residues 90-170. This pattern of response was similar to strongly proliferating wells that yielded CD4+ T cell clones specific for the 90-170 peptide. After repeated stimulation, however, no response to MBP or MBP 90-170 was detected, even though the number of cells increased after stimulation. Phenotyping and TCR analyses revealed the presence of two CD8+, CD4-, IL-2R+ T cell isolates that expressed a single V beta gene (V beta 17) that differed from the CD4+ isolates that uniformly expressed V beta 14. One of these CD8+ clones (C9) inhibited the antigen-driven proliferation of an autologous MBP 90-170 reactive clone but not an autologous clone specific for Herpes simplex virus (HSV), without affecting MHC non-restricted mitogen responses of the same clones. Moreover, C9 did not inhibit heterologous CD4+ T cell clones specific for MBP 1-38 or 90-170. A culture supernatant of the CD8+ clone showed the same pattern but lower levels of inhibition. C9 had mild cytolytic activity when incubated at high ratios with an autologous MBP-specific CD4+ clone. Lysis was blocked completely by anti-MHC class I antibodies, but not by anti-MHC II antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Location of a new encephalitogenic epitope (residues 43 to 64) in proteolipid protein that induces relapsing experimental autoimmune encephalomyelitis in PL/J and (SJL x PL)F1 mice

Synthetic peptides of proteolipid protein (PLP) were screened for their ability to induce experimental autoimmune encephalomyelitis (EAE) in SJL/J, PL/J, and (SJL x PL)F1 mice, and T cell lines were selected by stimulation of lymph node cells with PLP peptides. PLP 141-151 was found to be less encephalitogenic in SJL/J mice than PLP 139-151, due to deletion of two amino acids from the amino-terminal end. PLP 139-151 immunization induced relapsing EAE in SJL/J and F1 mice but not PL/J mice. In contrast, PLP 43-64 induced relapsing EAE in PL/J and F1 mice but not SJL/J mice. F1 T cell lines specific for either PLP 43-64 or PLP 139-151 adoptively transferred demyelinating EAE to naive F1 recipients. Haplotypes H-2s and H-2u appear to be immunologically co-dominant in F1 mice in the PLP EAE system, which differs from the H-2u dominance in F1 mice in the myelin basic protein EAE system. The identification of a PLP peptide that is encephalitogenic in PL/J mice, in addition to the previous demonstration of PLP peptides that are encephalitogenic for SWR mice (PLP 103-116) and SJL/J mice (PLP 139-151), lends support to a role for PLP as a target Ag in autoimmune demyelinating diseases.

Location of a new encephalitogenic epitope (residues 43 to 64) in proteolipid protein that induces relapsing experimental autoimmune encephalomyelitis in PL/J and (SJL x PL)F1 mice

Synthetic peptides of proteolipid protein (PLP) were screened for their ability to induce experimental autoimmune encephalomyelitis (EAE) in SJL/J, PL/J, and (SJL x PL)F1 mice, and T cell lines were selected by stimulation of lymph node cells with PLP peptides. PLP 141-151 was found to be less encephalitogenic in SJL/J mice than PLP 139-151, due to deletion of two amino acids from the amino-terminal end. PLP 139-151 immunization induced relapsing EAE in SJL/J and F1 mice but not PL/J mice. In contrast, PLP 43-64 induced relapsing EAE in PL/J and F1 mice but not SJL/J mice. F1 T cell lines specific for either PLP 43-64 or PLP 139-151 adoptively transferred demyelinating EAE to naive F1 recipients. Haplotypes H-2s and H-2u appear to be immunologically co-dominant in F1 mice in the PLP EAE system, which differs from the H-2u dominance in F1 mice in the myelin basic protein EAE system. The identification of a PLP peptide that is encephalitogenic in PL/J mice, in addition to the previous demonstration of PLP peptides that are encephalitogenic for SWR mice (PLP 103-116) and SJL/J mice (PLP 139-151), lends support to a role for PLP as a target Ag in autoimmune demyelinating diseases.

Analysis of T cell receptor beta chains in Lewis rats with experimental allergic encephalomyelitis: conserved complementarity determining region 3

This study explores the usage of T cell antigen receptor (TCR) beta chain elements in Lewis rats with experimentally induced allergic encephalomyelitis (EAE). TCRs from 15 different T cell clones and hybridomas derived from animals immunized with myelin basic protein (MBP), and all having specificity for the 21-mer encephalitogenic fragment MBP 68-88, utilized V beta 8.2. In addition, there was a marked conservation of the first two amino acid residues of the junctional complementarity determining region 3 (CDR3) associated with the V beta 8.2 receptors. 12 of 15 contained an aspartic acid followed by serine regardless of the associated J beta element. At the nucleotide level, this conservation of AspSer residues was accomplished with few or no nongermline-encoded nucleotide (N) additions. A similar pattern of AspSer usage and N region nucleotide additions was observed in a number of V beta 8.2 isolates derived from MBP-immunized lymph nodes. In contrast, V beta 8.2 polymerase chain reaction amplified isolates from Lewis T cells activated with concanavalin A or from lymph nodes of complete Freund's adjuvant-immunized animals showed no AspSer utilization (0/31) in the CDR3, and four to nine N region nucleotide additions. We conclude from this finding that AspSer residues in the CDR3, limited N region nucleotide additions, along with V beta 8.2 sequences, contribute to TCR specificity for MBP 68-88. This raises the possibility that encephalitogenic, disease-causing T cells either represent a population that derives from late fetal life or alternatively, that they are rare cells with this particular TCR phenotype contributed to the T cell pool throughout adulthood and are selected by antigen. In either case, the CDR3 AspSer sequences as well as V beta 8.2 sequences are candidates for the receptor target structures recognized by regulator T cells in recovery from and resistance to active EAE. In this respect, a preliminary analysis of TCR utilization in three T cell clones specific for MBP 68-88 isolated from animals recovered from active EAE indicates that while all three use V beta 8.2, only one contains AspSer in the CDR3.

Preferential T-cell receptor beta-chain variable gene use in myelin basic protein-reactive T-cell clones from patients with multiple sclerosis

Multiple sclerosis is an autoimmune disease in which T lymphocytes reactive to myelin basic protein (BP) could play a central role. T cells specific for BP were cloned from the blood of multiple sclerosis patients and normal individuals, and expression of T-cell receptor variable region genes was analyzed. A remarkable bias for use of beta-chain variable region (V beta) 5.2 and, to a lesser extent, V beta 6.1 was seen among BP-specific clones from patients but not from controls. The preferential use of V beta 5.2 for BP recognition did not reflect altered expression of this V beta in the peripheral repertoire. Interestingly, shared V beta 5.2 usage was apparent for clones specific for different BP determinants, even when derived from the same individual. The concurrent demonstration by others (J. R. Oksenberg, M. A. Panzara, A. B. Begovich, H. Erlich, R. Murray, M. Sherritt, S. Stuart, C. C. Bernard, and L. Steinman, personal communication) that T cells within demyelinating areas of multiple sclerosis brains preferentially express V beta 5.2 and V beta 6.1 suggests that the BP-specific clones derived from blood may be relevant to disease pathogenesis. These findings may have important implications for the treatment of multiple sclerosis.

Myelin basic protein specific T cell lines and clones derived from the CNS of rats with EAE only recognize encephalitogenic epitopes

The epitope specificities of myelin basic protein (BP) specific T cell lines derived from the spinal cords (SC) and lymph nodes (LN) of rats with experimental autoimmune encephalomyelitis (EAE) were compared. To induce EAE, Lewis rats were immunized with guinea pig (GP)-BP and complete Freund's adjuvant. Mononuclear cells from the SC and LN of these animals proliferated in response to BP and the purified protein derivative (PPD) of mycobacterium. After initially being cultured in growth medium, SC mononuclear cells had an enhanced response to BP and lost their response to PPD. LN cells cultured in identical conditions lost their response to both BP and PPD. LN-derived BP specific cell lines recognized only two epitopes of GP-BP: an encephalitogenic epitope in residues 72-89 and a non-encephalitogenic epitope in residues 43-68. SC-derived BP specific cell lines and clones recognized the 72-89 epitope and a second encephalitogenic epitope contained in residues 87-99 but not the non-encephalitogenic 43-68 epitope. Unlike those from LN, BP-specific T cell lines and clones derived from the CNS appear to recognize only encephalitogenic epitopes, including epitopes not recognized by LN lines.

Clonal diversity of basic protein specific T cells in Lewis rats recovered from experimental autoimmune encephalomyelitis

T cell lines selected from Lewis rats recovered from experimental autoimmune encephalomyelitis (EAE) respond not only to the immunodominant 72-89 epitope of basic protein (BP), but also to secondary epitopes including the I-A restricted 43-67 region of guinea pig (Gp) BP and the I-E restricted 87-99 sequence of rat (Rt) BP. The current study demonstrates at the clonal level the diversity of T cell responses to Gp- and Rt-BP in EAE-recovered rats. As predicted from the response pattern of BP-selected T cell lines, T cell clones from the lines responded to both the dominant and secondary epitopes of BP. In addition, a new majority clonal type was identified that responded to whole BP but not to epitopes represented on enzymatic cleavage fragments or synthetic peptides spanning the BP molecule. Clones representative of each of the three types of Gp-BP responses were characterized for phenotype, major histocompatibility complex restriction, and biologic activity in vivo. All of the clones were strongly CD4+ and co-expressed CD8 at modest levels as measured by both immunofluorescence and Northern blots. All three T cell specificities were I-A restricted. However, only the 72-89 responsive clone could transfer clinical EAE, due most likely to its unique ability to respond to Rt-BP. In contrast, the Gp-BP 43-67 reactive T cell clone transferred protection against EAE, whereas the whole Gp-BP reactive clone transferred delayed-type hypersensitivity response but was neither encephalitogenic nor protective. Thus, the recovery process from EAE is distinguished by an increased diversity of protective clones as well as innocuous clones that may be spawned as encephalitogenic T cells are regulated.

Ganglioside (GM1)-treated T cells shed CD4

In previous studies (Morrison et al., 1990), we showed that ganglioside (GM1) modulation of CD4 was associated with activation of phospholipase C and increased production of inositol triphosphate, but not with activation of protein kinase C. These results demonstrated a unique signal transduction pathway related to GM1 modulation of CD4 on T cells and raised the question as to whether intracellular Ca2+ levels and related protein kinases would be affected by GM1-induced signalling. We now show that GM1 modulation of CD4 from human T cells corresponds to decreased cellular Ca2+ without significant changes in cellular protein phosphorylation. In the course of this study we discovered that T cells challenged with GM1 exhibited new proteins in their surrounding media. Fractionation of cellular and supernatant proteins show that cells treated with GM1 released proteins with an approximate molecular weight (Mr) of 49,000. This was exclusive of GM1 protein association and GM1-induced protein phosphorylation. Immunoblots demonstrated the presence of CD4 in GM1-treated cell supernatants. Western immunoblots using anti-CD4 antibodies detected a lower Mr form (49,000) of CD4 in the supernatants of GM1-treated cells. These studies further define the unique nature of GM1 signalling relating to modulation of CD4 and demonstrate that the fate of GM1 modulated CD4, in part, involves protein shedding.

Protection against experimental encephalomyelitis. Idiotypic autoregulation induced by a nonencephalitogenic T cell clone expressing a cross-reactive T cell receptor V gene

The recovery process in experimental autoimmune encephalomyelitis (EAE) in Lewis rats is characterized by an increasing diversity of T cell clones directed at secondary epitopes of myelin basic protein. Of particular interest, residues 55 to 69 of guinea pig basic protein could induce protection against EAE. A nonencephalitogenic T cell clone, C455-69, that was specific for this epitope transferred protection against both active and passive EAE. Clone C4 was found to express V beta 8.6 in its Ag receptor, and residues 39 to 59 of the TCR V beta 8.6 sequence were found to be highly crossreactive with the corresponding residues 39 to 59 of TCR V beta 8.2, which is known to induce protective anti-idiotypic T cells and antibodies. Like the TCR V beta 8.2 peptide, the V beta 8.6 sequence induced autoregulation and provided effective treatment of established EAE. Thus, the EAE-protective effect of the guinea pig basic protein 55-69 sequence was most likely mediated by T cell clones such as C4 that could efficiently induce anti-TCR immunity directed at a cross-reactive regulatory idiotope.

Protection against experimental encephalomyelitis. Idiotypic autoregulation induced by a nonencephalitogenic T cell clone expressing a cross-reactive T cell receptor V gene

The recovery process in experimental autoimmune encephalomyelitis (EAE) in Lewis rats is characterized by an increasing diversity of T cell clones directed at secondary epitopes of myelin basic protein. Of particular interest, residues 55 to 69 of guinea pig basic protein could induce protection against EAE. A nonencephalitogenic T cell clone, C455-69, that was specific for this epitope transferred protection against both active and passive EAE. Clone C4 was found to express V beta 8.6 in its Ag receptor, and residues 39 to 59 of the TCR V beta 8.6 sequence were found to be highly crossreactive with the corresponding residues 39 to 59 of TCR V beta 8.2, which is known to induce protective anti-idiotypic T cells and antibodies. Like the TCR V beta 8.2 peptide, the V beta 8.6 sequence induced autoregulation and provided effective treatment of established EAE. Thus, the EAE-protective effect of the guinea pig basic protein 55-69 sequence was most likely mediated by T cell clones such as C4 that could efficiently induce anti-TCR immunity directed at a cross-reactive regulatory idiotope.

Specificity of human T cell clones reactive to immunodominant epitopes of myelin basic protein

Several recently discovered lines of evidence support the involvement of myelin basic protein (BP)-specific T cells in multiple sclerosis (MS). To identify potentially relevant immunodominant T cell epitopes, human BP (Hu-BP)-reactive T cell lines were selected from MS and normal donors and tested for reactivity to cleavage fragments and synthetic peptides of Hu-BP. The MS T cell lines responded to more Hu-BP epitopes than did normal lines, showing biased recognition of the N terminal half of the molecule, and one region in the C terminal half, suggesting increased sensitization to BP. The MS lines also differed from normal lines in their decreased percentage of CD8+ T cells. One hundred nine T cell clones isolated from these lines confirmed the reactivity pattern of the lines but did not reflect the mixed phenotype, since all but three clones tested were CD4+. T cell clones from HLA-DR2 homozygous donors responded to a variety of epitopes, indicating that this molecule was permissive in its ability to restrict T cell responses. Other epitopes, including the immunodominant 149-170 sequence, were restricted by several different major histocompatibility complex (MHC) molecules from both MS and normal donors. T cell receptor (TCR) V gene products could be identified on six of 38 clones tested using monoclonal antibodies. From one HLA-DR2 homozygous donor, four of eight clones utilized V beta 5.2 in response to different BP epitopes, providing initial support for the preferential use of a limited set of V region genes in the human response to BP. Preferential TCR V gene use in MS patients would provide the rationale to regulate selectively BP-reactive T cells through immunity directed at the TCR and thus test for the first time the hypothesis that BP-reactive T cells play a critical role in the pathogenesis of MS.

T cell receptor peptide therapy triggers autoregulation of experimental encephalomyelitis

Encephalitogenic T cells specific for myelin basic protein share common V beta 8 peptide sequences in their T cell receptor (TCR) that can induce autoregulatory T cells and antibodies that prevent clinical signs of experimental autoimmune encephalomyelitis (EAE). It is not known, however, if TCR peptides can treat established disease. To test its therapeutic value, TCR-V beta 8-39-59 peptide was injected into rats with clinical signs of EAE. This treatment reduced disease severity and speeded recovery, apparently by boosting anti-V beta 8 T cells and antibodies raised naturally in response to encephalitogenic V beta 8+ T cells. These results demonstrate that synthetic TCR peptides can be used therapeutically, and implicate the TCR-V beta 8-39-59 sequence as a natural idiotope involved in EAE recovery. Similarly, human TCR peptides may be effective in enhancing natural regulation of autoreactive T cells that share common V genes.

T cell lines specific for an immunodominant epitope of human basic protein define an encephalitogenic determinant for experimental autoimmune encephalomyelitis-resistant LOU/M rats

The LOU/M rat (RT-1w) haplotype, although resistant to an encephalitogenic challenge of guinea pig myelin basic protein (Gp-BP)/CFA and unresponsive to Gp-BP, responded strongly to human (Hu)-BP. Both T cell and antibody responses focused on the 110-129 determinant of Hu-BP, and T cells specific for this epitope transferred clinical and histologic experimental autoimmune encephalomyelitis (EAE) to naive LOU/M rats. Moreover, EAE could be induced actively with Hu-BP and a synthetic Hu-S110-129 peptide in CFA, but only with co-immunomodulation by pertussis toxin or cyclophosphamide. Analysis of TCR V region genes revealed the predominant use of the V beta 8.5-J beta 2.3 gene combination, with extensive N region additions to both D beta 1 and D beta 2. These results define the Hu-BP 110-129 peptide sequence as the major encephalitogenic epitope for the LOU/M strain of rat previously considered resistant to EAE, and support the idea that the encephalitogenic property of BP and other CNS Ag for a given MHC is encompassed within immunodominant T cell epitopes. Furthermore, the TCR sequence data indicate the predominant use of a different V beta 8 subfamily member (V beta 8.5) than the V beta 8.2 gene used preferentially by several other rat strains and the PL/J mouse in the T cell response to BP.

T cell lines specific for an immunodominant epitope of human basic protein define an encephalitogenic determinant for experimental autoimmune encephalomyelitis-resistant LOU/M rats

The LOU/M rat (RT-1w) haplotype, although resistant to an encephalitogenic challenge of guinea pig myelin basic protein (Gp-BP)/CFA and unresponsive to Gp-BP, responded strongly to human (Hu)-BP. Both T cell and antibody responses focused on the 110-129 determinant of Hu-BP, and T cells specific for this epitope transferred clinical and histologic experimental autoimmune encephalomyelitis (EAE) to naive LOU/M rats. Moreover, EAE could be induced actively with Hu-BP and a synthetic Hu-S110-129 peptide in CFA, but only with co-immunomodulation by pertussis toxin or cyclophosphamide. Analysis of TCR V region genes revealed the predominant use of the V beta 8.5-J beta 2.3 gene combination, with extensive N region additions to both D beta 1 and D beta 2. These results define the Hu-BP 110-129 peptide sequence as the major encephalitogenic epitope for the LOU/M strain of rat previously considered resistant to EAE, and support the idea that the encephalitogenic property of BP and other CNS Ag for a given MHC is encompassed within immunodominant T cell epitopes. Furthermore, the TCR sequence data indicate the predominant use of a different V beta 8 subfamily member (V beta 8.5) than the V beta 8.2 gene used preferentially by several other rat strains and the PL/J mouse in the T cell response to BP.

Lymphocytes from SJL/J mice immunized with spinal cord respond selectively to a peptide of proteolipid protein and transfer relapsing demyelinating experimental autoimmune encephalomyelitis

Relapsing experimental autoimmune encephalomyelitis (R-EAE) can be induced in SJL/J mice by immunization with spinal cord homogenate and adjuvant. The specific Ag(s) responsible for acute disease and subsequent relapses in this model is unknown. Myelin basic protein (BP), an encephalitogenic peptide of BP (BP 87-99), and proteolipid protein (PLP) can each induce R-EAE in SJL/J mice, and a peptide of PLP (PLP 139-151) has been reported to induce acute EAE. To determine the encephalitogens in cord-immunized mice with R-EAE, the in vitro proliferative responses of lymph node cells (LNC) and central nervous system mononuclear cells to BP, BP peptides, and PLP peptides were examined during acute EAE and during relapses. LNC responded only to PLP peptides 139-151 and 141-151 and did not respond to BP or its peptides during acute or chronic disease. Central nervous system mononuclear cells also preferentially responded to PLP 139-151 and 141-151 during acute and relapsing disease. A PLP 139-151 peptide-specific Th cell line was selected from LNC of cord-immunized donors. Five million peptide-specific line cells transferred severe relapsing demyelinating EAE to naive recipients. We conclude that PLP peptide 139-151 is the major encephalitogen for R-EAE in cord-immunized SJL/J mice. We demonstrate for the first time that Th cells specific for this peptide are sufficient to transfer relapsing demyelinating EAE. The predominance of a PLP immune response rather than a BP response in SJL/J mice suggests that genetic background may determine the predominant myelin Ag response in human demyelinating diseases such as multiple sclerosis.

Lymphocytes from SJL/J mice immunized with spinal cord respond selectively to a peptide of proteolipid protein and transfer relapsing demyelinating experimental autoimmune encephalomyelitis

Relapsing experimental autoimmune encephalomyelitis (R-EAE) can be induced in SJL/J mice by immunization with spinal cord homogenate and adjuvant. The specific Ag(s) responsible for acute disease and subsequent relapses in this model is unknown. Myelin basic protein (BP), an encephalitogenic peptide of BP (BP 87-99), and proteolipid protein (PLP) can each induce R-EAE in SJL/J mice, and a peptide of PLP (PLP 139-151) has been reported to induce acute EAE. To determine the encephalitogens in cord-immunized mice with R-EAE, the in vitro proliferative responses of lymph node cells (LNC) and central nervous system mononuclear cells to BP, BP peptides, and PLP peptides were examined during acute EAE and during relapses. LNC responded only to PLP peptides 139-151 and 141-151 and did not respond to BP or its peptides during acute or chronic disease. Central nervous system mononuclear cells also preferentially responded to PLP 139-151 and 141-151 during acute and relapsing disease. A PLP 139-151 peptide-specific Th cell line was selected from LNC of cord-immunized donors. Five million peptide-specific line cells transferred severe relapsing demyelinating EAE to naive recipients. We conclude that PLP peptide 139-151 is the major encephalitogen for R-EAE in cord-immunized SJL/J mice. We demonstrate for the first time that Th cells specific for this peptide are sufficient to transfer relapsing demyelinating EAE. The predominance of a PLP immune response rather than a BP response in SJL/J mice suggests that genetic background may determine the predominant myelin Ag response in human demyelinating diseases such as multiple sclerosis.

Myelin basic protein-specific T cells induce demyelinating experimental autoimmune encephalomyelitis in Buffalo rats

This is the first description of acute demyelinating experimental autoimmune encephalomyelitis (EAE) induced in rats by myelin basic protein (BP)-specific T lymphocytes without the administration of demyelinating antibodies. BP-specific T cell lines were selected from inbred Buffalo-strain rats (Rt-1b) following techniques used to develop similar lines from Lewis rats (Rt-1l). Unlike those of Lewis rats, the spinal cords of Buffalo rats with T cell line-mediated EAE had prominent perivascular demyelination associated with mononuclear inflammation. Like Lewis rat lines. Buffalo rat BP-specific T cell lines transferred acute, non-relapsing EAE into syngeneic recipients, demonstrating that demyelination in passive acute EAE can occur without subsequent clinical relapses.

Transmembrane signalling associated with ganglioside-induced CD4 modulation

Ganglioside (GM1) treatment of CD4+ human CEM lymphoma cells stimulated transient phosphoinositide (PI) breakdown, production of inositol phosphates (IP), protein phosphorylation and rapid decrease of CD4 surface expression. A comparison between the actions of GM1 and other agents that affect these signal transduction pathways demonstrated a distinct mechanism for GM1-induced decrease of CD4. GM1 stimulated both phospholipase C activity and protein phosphorylation but had no effect on either cellular cAMP levels or tyrosine kinase activity. Phorbol myristate acetate (PMA) stimulated protein phosphorylation and caused a significant decrease in surface display of CD4. Both of these processes were blocked by pretreating cells with the protein kinase C (PKC) inhibitor H7. These results demonstrate that GM1 stimulates PI turnover and induces a rapid decrease of CD4 surface expression by processes that do not activate adenylate cyclase or tyrosine kinase. They further demonstrate that the mechanism for GM1-induced decrease of CD4 is distinct from the CD4 internalization processes mediated by PKC activity.

Recombinant human beta-galactoside binding lectin suppresses clinical and histological signs of experimental autoimmune encephalomyelitis

Human placental tissue contains regulatory molecules that may prevent allo-sensitization. Recently, a 14 kDa beta-galactoside binding protein with demonstrated immunoregulatory properties has been cloned using cDNA from human placenta and expressed in Escherichia coli. The present study assesses the ability of this recombinant immunomodulatory lectin (rIML-1), to prevent experimental autoimmune encephalomyelitis (EAE), a paralytic T cell-mediated disease directed against myelin basic protein (BP). Injection of rIML-1 into Lewis rats inhibited the induction of both clinical and histological signs of EAE, apparently by blocking sensitization of encephalitogenic BP-specific T cells and inducing BP-dependent suppressor cells. Because it is neither immunogenic nor toxic, rIML-1 may have application in humans, and would have distinct advantages over unselective cytotoxic immunosuppressive agents used currently in the treatment of autoimmune diseases and transplantation.

Antibodies specific for VB8 receptor peptide suppress experimental autoimmune encephalomyelitis

Recent studies from our laboratory have shown, for the first time, that a synthetic peptide from that TCR VB chain used preferentially by encephalitogenic T cells induced the formation of protective, MHC class I-restricted T cells and prevented the development of EAE in Lewis rats. In this report we 1) demonstrate that immunization with the TCR-VB8-39-59 peptide generated peptide-specific antibodies that protect against experimental autoimmune encephalomyelitis induced by either of the two distinct encephalitogenic epitopes of basic protein, and 2) characterize the production and biologic functions of rat and rabbit antibody responses to the TCR peptide. The antibodies in both species increased in titer over time, were highly specific for the immunogen by direct reaction and inhibition assays, stained only VB8+ T cells, and suppressed clinical signs and to lesser extent the number of histologic lesions of experimental autoimmune encephalomyelitis mediated by VB8+ T cells. Coupled with our previous work, these results indicate that both humoral and cellular responses to the TCR-VB8-39-59 peptide can contribute independent immunoregulatory effects on encephalitogenic T lymphocytes that use common V region genes in response to epitopes of myelin basic protein.

Antibodies specific for VB8 receptor peptide suppress experimental autoimmune encephalomyelitis

Recent studies from our laboratory have shown, for the first time, that a synthetic peptide from that TCR VB chain used preferentially by encephalitogenic T cells induced the formation of protective, MHC class I-restricted T cells and prevented the development of EAE in Lewis rats. In this report we 1) demonstrate that immunization with the TCR-VB8-39-59 peptide generated peptide-specific antibodies that protect against experimental autoimmune encephalomyelitis induced by either of the two distinct encephalitogenic epitopes of basic protein, and 2) characterize the production and biologic functions of rat and rabbit antibody responses to the TCR peptide. The antibodies in both species increased in titer over time, were highly specific for the immunogen by direct reaction and inhibition assays, stained only VB8+ T cells, and suppressed clinical signs and to lesser extent the number of histologic lesions of experimental autoimmune encephalomyelitis mediated by VB8+ T cells. Coupled with our previous work, these results indicate that both humoral and cellular responses to the TCR-VB8-39-59 peptide can contribute independent immunoregulatory effects on encephalitogenic T lymphocytes that use common V region genes in response to epitopes of myelin basic protein.

Suppressor cell regulation of encephalitogenic T cell lines: generation of suppressor macrophages with cyclosporin A and myelin basic protein

Chronic relapsing experimental allergic encephalomyelitis (CR-EAE) can be adoptively transferred using myelin basic protein (BP)-specific helper T cell lines, and suppressor cells may be important in recovery from EAE. In order to generate suppressor cells, spleen cells obtained from BP-complete Freund's adjuvant (CFA) inoculated SJL/J mice and from normal mice were cultured for 7 days with medium, with cyclosporin A (CsA), or with CsA and antigen (BP or purified protein derivative of mycobacterium (PPD)). Cultured spleen cells were assayed for suppressor activity in vitro by coculture with BP-specific and PPD-specific helper T cell lines derived from SJL/J mice. Immunized donor spleen cells cultured with cyclosporin A (CsA) and BP were potent inhibitors of T cell line proliferation, and suppressor activity was increased 17-fold compared with control splenocytes. The number of suppressor cells required to suppress PPD-specific line proliferation by 50% (I50) was significantly higher than the number required to suppress BP-specific line proliferation, suggesting an antigen-specific component to the suppression. The major effector cell required for suppression was a large granular Mac-1+ cell with the functional characteristics of a macrophage. Suppressor activity persisted after depletion of Thy 1.2+ cells, but suppression was no longer antigen-specific, suggesting that culture of spleen cells with CsA and BP may generate suppressor macrophages which are antigen-nonspecific and Thy 1.2+ suppressor cells which are antigen-specific. These suppressor cells may be important in the regulation of CR-EAE and the techniques described for their generation may prove useful for treatment and prevention of disease.

Characterization of basic protein-specific T cell lines selected from Lewis rats with relapsing experimental autoimmune encephalomyelitis

Relapsing experimental autoimmune encephalomyelitis (EAE) was induced in Lewis rats by intraperitoneal immunization with guinea pig whole central nervous system tissue. Basic protein (BP)-specific T cell lines selected from rats with relapsing EAE proliferated in response to BP, the 44-89 peptidase fragment of BP and the synthetic peptide, S72-89, as did lines selected from rats with non-relapsing EAE induced by immunization with guinea pig BP. BP-specific T cell lines selected from rats with relapsing EAE transferred acute but not relapsing EAE. BP-specific T cell lines selected from Lewis rats with relapsing EAE appear not to differ from those selected from rats with non-relapsing EAE.

Determinants of human myelin basic protein that induce encephalitogenic T cells in Lewis rats

Due to critical amino acid changes in the 72-89 sequence, the determinant of human (Hu) basic protein (BP) that induces experimental autoimmune encephalomyelitis (EAE) in Lewis rats most likely differs from rat and guinea pig BP. To discern encephalitogenic sequence(s), the immunodominant epitopes recognized by Hu-BP-specific T cell lines were identified using synthetic peptides that corresponded to the Hu-BP sequence. The Hu-BP-reactive T cell line contained two distinct specificities, one directed at the 87-99 (Hu) sequence restricted by I-E, and the second directed at the 55-74 (Hu) sequence restricted by I-A. T cells specific for the 87-99 determinant recognized both Hu- and Rt-BP, were highly encephalitogenic, and accounted for the experimental autoimmune encephalomyelitis-inducing activity of the Hu-BP line. T cells directed at the S55-74 (Hu) sequence did not recognize Rt-BP and were not encephalitogenic. The same TCR V genes (homologous to the mouse V alpha 2 and V beta 8 families) that we showed previously were utilized preferentially in response to the I-A restricted 72-89 encephalitogenic sequence were also present in T cell lines specific for both the S55-74 and S87-99 epitopes. These data indicate that encephalitogenic activity of BP in Lewis rats is related to discrete T cell epitopes that are present on or cross-react with rat-BP. Furthermore it would appear that genes in the TCR V alpha 2 and V beta 8 families are widely used in response to different BP epitopes restricted by either I-A or I-E molecules.

Determinants of human myelin basic protein that induce encephalitogenic T cells in Lewis rats

Due to critical amino acid changes in the 72-89 sequence, the determinant of human (Hu) basic protein (BP) that induces experimental autoimmune encephalomyelitis (EAE) in Lewis rats most likely differs from rat and guinea pig BP. To discern encephalitogenic sequence(s), the immunodominant epitopes recognized by Hu-BP-specific T cell lines were identified using synthetic peptides that corresponded to the Hu-BP sequence. The Hu-BP-reactive T cell line contained two distinct specificities, one directed at the 87-99 (Hu) sequence restricted by I-E, and the second directed at the 55-74 (Hu) sequence restricted by I-A. T cells specific for the 87-99 determinant recognized both Hu- and Rt-BP, were highly encephalitogenic, and accounted for the experimental autoimmune encephalomyelitis-inducing activity of the Hu-BP line. T cells directed at the S55-74 (Hu) sequence did not recognize Rt-BP and were not encephalitogenic. The same TCR V genes (homologous to the mouse V alpha 2 and V beta 8 families) that we showed previously were utilized preferentially in response to the I-A restricted 72-89 encephalitogenic sequence were also present in T cell lines specific for both the S55-74 and S87-99 epitopes. These data indicate that encephalitogenic activity of BP in Lewis rats is related to discrete T cell epitopes that are present on or cross-react with rat-BP. Furthermore it would appear that genes in the TCR V alpha 2 and V beta 8 families are widely used in response to different BP epitopes restricted by either I-A or I-E molecules.

Immunization with a synthetic T-cell receptor V-region peptide protects against experimental autoimmune encephalomyelitis

T cells expressing the alpha beta T-cell receptor (TCR) for antigen can elicit anti-idiotypic antibodies specific for the TCR that regulate T-cell function. Defined sequences of the TCR, however, have not been used to elicit specific antibodies and the role of cellular immunity directed against TCR determinants has not been studied. We immunized Lewis rats with a synthetic peptide representing a hypervariable region of the TCR V beta 8 molecule. Subsequent induction of experimental autoimmune encephalomyelitis, a paralytic disease of the central nervous system mediated primarily by V beta 8+ T cells specific for myelin basic protein was prevented. T cells specific for the TCR V beta 8 peptide conferred passive protection against the disease to naive rats, apparently by shifting the predominant T-cell response away from the major encephalitogenic epitope of basic protein. This is the first report demonstrating the use of a synthetic TCR V-region peptide to induce specific regulatory immunity and has important implications for the regulation of human disease characterized by common TCR V-gene usage.

PHA activation of encephalitogenic T cells: in vitro line selection overcomes splenic suppression

In this study we compared myelin basic protein (MBP) and phytohemagglutinin (PHA) for their ability to induce proliferation and experimental autoimmune encephalomyelitis (EAE) transfer activity in mixed cell cultures obtained from spleen and lymph nodes versus highly selected MBP-specific T cell lines and clones. Established MBP-specific cells derived initially from immune lymph nodes attained both proliferative and EAE-transfer activities after in vitro activation with either MBP or PHA. In contrast, PHA was unable to induce immune spleen cells to transfer EAE, in spite of its potent mitogenic activity. On the basis of these results, we evaluated the in vitro proliferation and differentiation responses of MBP-specific T cells during the line selection process using cells derived from both immune lymph node and immune spleen. During the initial selection process with MBP, proliferation of MBP-specific T cell precursors from immunized spleen populations was reduced relative to lymph node cells. After antigen-dependent selection the encephalitogenic cells from either organ exhibited identical in vitro response characteristics. Freshly isolated immune spleen cells were potent suppressors of MBP-specific T cell proliferation suggesting that the in vitro differences between the two organs was due to splenic suppression of the encephalitogenic cells.

Defective T helper cell epitope responsible for the failure of region 69-84 of the human myelin basic protein to induce experimental allergic encephalomyelitis in the Lewis rat

Studies from our laboratory have shown that region 69-84 (synthetic peptide S49S) of myelin basic protein (MBP) defines an encephalitogenic sequence for experimental allergic encephalomyelitis (EAE) in Lewis rats. The most potent EAE inducers are the guinea pig MBP (Gp-MBP) and region 69-84, known as synthetic peptide Gp-S49S: (See text: formula). Human (H-MBP) was considerably less potent than Gp-MBP, and region 69-84 (H-S49S) of H-MBP did not induce hind leg paralysis or any histological signs of EAE. Since the development of EAE requires the expression of specific T and B cell epitopes, sequence analysis of H-S49S and Gp-S49S revealed phylogenetic variations in the H-S49S sequence, characterized by positions 77 and 78, and substitution of Ser with Thr at position 80: (See text: formula). Like Gp-S49S, peptide H-S49S induced the formation of antibodies with specificities directed against the C-terminal of the H-S49S, Gp-S49S, and homologous sequences. In contrast to Gp-S49S, neither II-S49S nor shorter peptides induced clonal T cell expansion when either of the peptides was added to encephalitogenic T cell clone D in culture. Clone D, which expresses T helper phenotype, was selected from encephalitogenic peptide-primed Lewis rats. The results of the study show that the failure of H-S49S to induce EAE is related to sequence alterations in the T helper cell epitope but not in the B cell epitope located in the N- and C-terminal portions of the S49S sequence, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Human B cell lines secreting IgM antibody specific for myelin basic protein

In this study we describe for the first time the production of stable human B cell lines and clones that secrete IgM antibody specific for human myelin basic protein. The technique based on limiting dilutions of Epstein-Barr virus-transformed peripheral B cells from patients with multiple sclerosis, precluded the need for preselecting or stimulating antigen-specific B cells. Most of the cell lines were stable for at least 6 months in continuous culture and produced 5-12 micrograms/ml antibody after 2 weeks in culture. The myelin basic protein-specific B cells were surface IgM positive, and occurred with a frequency of approximately 1/2500 mononuclear cells in peripheral blood. The successful selection and quantitation of specific B cell clones described here suggests that this technique is well suited for evaluating B cell responses to known and suspected antigens and autoantigens.

Murine monoclonal anti-myelin basic protein (MBP) antibodies inhibit proliferation and cytotoxicity of MBP-specific human T cell clones

Myelin basic protein (MBP)-specific T cell clones, isolated from two patients with multiple sclerosis, expressed the CD4+ phenotype and induced MBP-dependent cytolysis of autologous Epstein-Barr virus (EBV)-transformed B cells. The proliferation and cytolytic activity of the T cell clones were inhibited by four of a panel of five murine monoclonal anti-MBP antibodies in a dose-dependent manner. An isotype-matched antibody with an irrelevant specificity did not have such an effect. These MBP-specific monoclonal antibodies did not block phytohemagglutinin-induced T cell proliferation or allospecific cytotoxicity. These results suggest that some antibodies directed at the autoantigen MBP may play a regulatory role in T cell activation, rather than a pathogenic role, for which there is currently little supporting evidence.

Human B cell lines secreting IgM antibody specific for myelin basic protein

In this study we describe for the first time the production of stable human B cell lines and clones that secrete IgM antibody specific for human myelin basic protein. The technique based on limiting dilutions of Epstein-Barr virus (EBV)-transformed peripheral B cells from patients with multiple sclerosis precluded the need for preselecting or stimulating antigen-specific B cells. Most of the cell lines were stable for at least 6 months in continuous culture and produced 5-12 micrograms/ml antibody after 2 weeks in culture. The myelin basic protein (MBP)-specific B cells were surface IgM positive, and occurred with a frequency of approximately 1/2500 mononuclear cells in peripheral blood. The successful selection and quantitation of specific B cell clones described here suggests that this technique is well suited for evaluating B cell responses to known and suspected antigens and autoantigens.

T cell determinants of myelin basic protein include a unique encephalitogenic I-E-restricted epitope for Lewis rats

The major encephalitogenic epitope for Lewis rats is the 72-89 sequence of guinea pig basic protein (GP-BP) or rat basic protein (Rt-BP). T cells responsive to this epitope are I-A restricted and preferentially express the V alpha 2:V beta 8 gene combination in their TCR. In this work, we describe for the first time the delayed appearance of T cells specific for additional discrete determinant of BP, the nonencephalitogenic 55-68 sequence of GP-BP restricted by I-A, and the encephalitogenic 87-99 sequence of Rt-BP restricted by I-E. The TCR V alpha 2:V beta 8 gene combination was expressed by both encephalitogenic GP-BP S72-89 and Rt-BP S87-99 T cell specificities but not by GP-BP 44-68-specific T cells. This is the first demonstration of I-E-restricted encephalitogenic T cells in Lewis rats and supports the conclusion that the I-E class II locus is involved in autoimmune diseases.

A common epitope on human myelin basic protein and the human T lymphocyte CD3 molecule

In this report, we describe for the first time an epitope common to human myelin basic protein (H.MBP), a structural component of central nervous system myelin, and T lymphocyte CD3, an activation molecule important in signal transduction. This cross-reactive determinant was recognized by a murine mAb WW.B1, which was raised against H.MBP. WW.B1 recognized PBMC and the Jurkat T leukemic cell line, immunoprecipitated both H.MBP and a complex indistinguishable from CD3, and possessed the same biologic properties--induction of T lymphocyte proliferation and inhibition of CTL function--as commercially available anti-CD3 antibodies. It is likely, however, that the epitope recognized by WW.B1 is distinct from those recognized by the anti-CD3 mAb OKT3 and anti-Leu-4. Although the biologic importance of this common determinant awaits further clarification, it is conceivable that autoimmunization to MBP could induce similar immunoregulatory antibody specificities.

Response of human T lymphocyte lines to myelin basic protein: association of dominant epitopes with HLA class II restriction molecules

In animals, the selection in vitro of T cell lines to myelin basic protein (MBP) can define immunodominant and encephalitogenic epitopes which are preferentially associated with class II major histocompatibility (MHC) molecules. These principles were used to evaluate the specificity and MHC restriction of 14 human MBP-reactive T cell lines selected from normal individuals and patients with multiple sclerosis (MS) and other neurological diseases (OND). The four normal T cell lines recognized single, separate immunodominant MBP epitopes which were restricted by MHC molecules from the DR or in one case the DP class II locus. In contrast, the MS and OND T cell lines recognized multiple MBP epitopes, each in association with a discrete class II MHC molecule from the DR or DQ locus. Overall, HLA-DR molecules were used preferentially to associate with epitopes on human MBP, restricting 26/33 responses. As predicted from animal studies, T cells from genetically disparate individuals responded to different immunodominant epitopes on human MBP in association with distinct MHC class II molecules. HLA-DR2, which is overrepresented in MS patients, possessed an unusual capacity to restrict all eight epitopes identified on MBP in this study. These data provide the first evidence of genetically restricted human T cell recognition of potentially encephalitogenic epitopes of MBP.

A common epitope on human myelin basic protein and the human T lymphocyte CD3 molecule

In this report, we describe for the first time an epitope common to human myelin basic protein (H.MBP), a structural component of central nervous system myelin, and T lymphocyte CD3, an activation molecule important in signal transduction. This cross-reactive determinant was recognized by a murine mAb WW.B1, which was raised against H.MBP. WW.B1 recognized PBMC and the Jurkat T leukemic cell line, immunoprecipitated both H.MBP and a complex indistinguishable from CD3, and possessed the same biologic properties--induction of T lymphocyte proliferation and inhibition of CTL function--as commercially available anti-CD3 antibodies. It is likely, however, that the epitope recognized by WW.B1 is distinct from those recognized by the anti-CD3 mAb OKT3 and anti-Leu-4. Although the biologic importance of this common determinant awaits further clarification, it is conceivable that autoimmunization to MBP could induce similar immunoregulatory antibody specificities.

Human T lymphocyte response to myelin basic protein: selection of T lymphocyte lines from MBP-responsive donors

The goal of this study was to delineate the importance of blood T lymphocyte responses to several myelin basic protein (MBP) preparations in the ultimate selection of MBP-specific T lymphocyte lines. Proliferation responses to human myelin basic protein (MBP) were assessed in blood samples from 27 multiple sclerosis (MS) patients, 20 patients with other neurologic diseases (OND), and 26 normal subjects, using five MBP preparations with different histories and electrophoretic characteristics to enhance the spectrum of epitopes represented. Substantial variations were observed in the ability of different MBP preparations to induce blood T cell proliferation in a given donor. However, four out of five of the MBPs induced modest but significant proliferation in the MS study population relative to normal individuals, with intermediate responses occurring in OND patients. Positive responses occurred more frequently in MS patients (78%) than in normal donors (31%), and were an important prerequisite for the successful selection of MBP-specific T cell lines.

T cell lines selected with synthetic peptides are highly encephalitogenic in SJL/J mice

T cell lines were selected from basic protein (BP)-immunized SJL/J mice using synthetic peptides encompassing the major SJL/J encephalitogenic determinant. Synthetic peptide-derived T cell lines proliferated in response to BP, the 89-169 peptidase fragment of BP and the synthetic peptides, pM87-99, pM90-99 and pM91-99. These lines transferred a demyelinating and chronic relapsing form of experimental autoimmune encephalomyelitis (EAE) into naive mice, and EAE induced by synthetic peptide-derived lines was more severe than that induced by whole BP-derived lines. This study demonstrates that T cell lines selected with synthetic peptides are encephalitogenic in SJL/J mice and offers an improved means for selecting SJL/J encephalitogenic T cell lines.

Selection of encephalitogenic rat T-lymphocyte clones recognizing an immunodominant epitope on myelin basic protein

Using the soft agar-cloning technique, we isolated 13 T-cell clones from guinea pig basic protein (GP-BP)-specific T-cell lines derived from Lewis rats. The clonal frequency was approximately 2.5 x 10(-5). Each of these clones had a similar but not identical pattern of response to a battery of synthetic peptides representing overlapping epitopes in the encephalitogenic region for Lewis rats (69-89 sequence). All clones responded to the minimal encephalitogenic sequence (residues 72-84) restricted by I-A but not I-E molecules, and all transferred clinical experimental autoimmune encephalomyelitis (EAE) and delayed-type hypersensitivity (DTH) reaction to naive rats. Phenotypically, the clones were W3/13+ (total T), W3/25+ (T helper), and OX-22+ (DTH associated). This report demonstrates for the first time the applicability of the soft agar-cloning technique for obtaining encephalitogenic T-cell clones. The exclusive recovery of 72-84-specific T-cell clones after only two rounds of stimulation with GP-BP indicates the immunodominance of this epitope and the power of the line selection technique for obtaining encephalitogenic T-cell specificities.

Both rat and mouse T cell receptors specific for the encephalitogenic determinant of myelin basic protein use similar V alpha and V beta chain genes even though the major histocompatibility complex and encephalitogenic determinants being recognized are different

Prospects for specific immune intervention in T cell-mediated autoimmune disease via anti-idiotypic regulation depend on the degree of diversity of the responder cell antigen receptor repertoire. A highly heterogenous response against self epitopes offers little chance for such regulation. We report here that the Lewis rat autoimmune disease experimental allergic encephalomyelitis, generally considered to be a model of human multiple sclerosis, is caused by T cells that use a limited set of TCR V genes. We have cloned the rat TCR alpha and beta chain cDNAs from the Lewis rat x mouse T cell hybridoma 510, which retains the rat specificity for the encephalitogenic determinant of myelin basic protein (MBP). Using Northern blot analysis of T cell RNA with the cloned V region probes, we have found a specific, and near perfect, correlation between expression of TCR message hybridizing to the V alpha 510 and VB510 probes and specificity for the encephalitogenic determinant of MBP in both T cell hybridomas and encephalitogenic T cell clones. This restricted V gene usage provides a basis for observed idiotypic regulation of auto-reactive T cells, and possible therapy for autoimmune disease. A curious and unexplained observation is that the Lewis rat V alpha/V beta combination that dominates the encephalitogenic response to the 68-88 peptide of MBP is precisely the same V alpha/V beta combination used by the B10.PL mouse response to the encephalitogenic response to the 1-9 peptide of MBP.

Lymphocyte vaccination against experimental autoimmune encephalomyelitis: evaluation of vaccination protocols

Repeated vaccination with encephalitogenic but not other T cell lines could effect marked resistance to 'active' experimental autoimmune encephalomyelitis (EAE) induced by injection of GP-BP in adjuvant. Partial resistance to active EAE was observed in rats recovered from 'passive' line-mediated EAE and in rats vaccinated with T cells attenuated by irradiation or ganglioside treatment. However, no resistance was observed in animals given low doses of activated encephalitogenic T cells. Treatment with hydrostatic pressure alone was found to be ineffective as a means of attenuation, and vaccination with pressure-treated encephalitogenic T cells actually induced mild signs of EAE. However, vaccination with cells that were first pressure treated and then irradiated prevented both clinical and histologic signs of active EAE. In contrast, protection against passive EAE appeared to be clonotypic. Lymphocyte vaccination induced delayed type hypersensitivity (DTH) reactions against autologous T cells, mostly to shared antigens, demonstrating the immunogenicity of multiple antigens on the vaccinating cells.

Specific ganglioside binding to receptor sites on T lymphocytes that couple to ganglioside-induced decrease of CD4 expression

The binding of different gangliosides to rat T-helper lymphocytes was characterized under conditions that decrease CD4 expression on different mammalian T-helper lymphocytes. Saturation binding by monosialylated [3H]-GM1 to rat T-lymphocytes was time- and temperature-dependent, had a dissociation constant (KD) of 2.2 +/- 1.4 microM and a binding capacity near 2 fmoles/cell. Competitive inhibition of [3H]-GM1 binding demonstrated a structural-activity related to the number of unconstrained sialic acid moieties on GM1-congeneric gangliosides. A comparison between the results of these binding studies and ganglioside-induced decrease of CD4 expression demonstrated that every aspect of [3H]-GM1 binding concurs with ganglioside modulation of CD4 expression. It is concluded that the specific decrease of CD4 expression induced by pretreatment with gangliosides involves the initial process of ganglioside binding to specific sites on CD4+ T-helper lymphocytes.

Encephalitogenic T cell clones with variant receptor specificity

We explored antigenic differences between guinea pig (GP)-basic protein (BP), rat (Rt)-BP, and respective peptides from the encephalitogenic region for Lewis rats by comparing the fine specificity of T lymphocyte lines and clones selected from animals primed with these Ag. Encephalitogenic T cell lines specific for GP-BP or Rt-BP predictably recognized the corresponding 72-89 and to a lesser degree the 72-84 (S55S) amino acid sequence. T cell lines selected from rats primed with GP-S55S responded preferentially to GP-S55S compared to other peptides. A T cell line raised to Rt-S55S, however, initially recognized the S55S and S72-89 peptides but were nearly unresponsive to the intact GP-BP or Rt-BP. T cell clones selected from the Rt-S55S line at that point had two distinct patterns of response: clones that recognized both of the BP and the S55S peptides adoptively transferred delayed-type hypersensitivity and experimental autoimmune encephalomyelitis. These clones also recognized residues 69-81 (S67) but not peptide S75-89. In contrast, T cell clones that responded only to synthetic peptides GP-S55S and Rt-S55S but not to the parent BP adoptively transferred delayed-type hypersensitivity but not disease in Lewis rats. The same clones failed to respond to either the S67 or the S75-89 sequences. These results demonstrate that the encephalitogenic Rt-S55S sequence houses a minimum of two T cell epitopes with differing specificities and functions. One epitope is immuno-dominant and resembles the encephalitogenic region of the intact BP molecule. The second non-encephalitogenic epitope is restricted to the S55S sequences and is not shared by the parent BP, the S67, or the S75-89 sequences. Both types of Rt-S55S-specific clones differ in fine specificity from encephalitogenic clones selected from GP-BP immunized rats, thus indicating that uniformity of T cell recognition of the encephalitogenic epitope is not an absolute condition for T cells to be encephalitogenic.

Encephalitogenic T cell clones with variant receptor specificity

We explored antigenic differences between guinea pig (GP)-basic protein (BP), rat (Rt)-BP, and respective peptides from the encephalitogenic region for Lewis rats by comparing the fine specificity of T lymphocyte lines and clones selected from animals primed with these Ag. Encephalitogenic T cell lines specific for GP-BP or Rt-BP predictably recognized the corresponding 72-89 and to a lesser degree the 72-84 (S55S) amino acid sequence. T cell lines selected from rats primed with GP-S55S responded preferentially to GP-S55S compared to other peptides. A T cell line raised to Rt-S55S, however, initially recognized the S55S and S72-89 peptides but were nearly unresponsive to the intact GP-BP or Rt-BP. T cell clones selected from the Rt-S55S line at that point had two distinct patterns of response: clones that recognized both of the BP and the S55S peptides adoptively transferred delayed-type hypersensitivity and experimental autoimmune encephalomyelitis. These clones also recognized residues 69-81 (S67) but not peptide S75-89. In contrast, T cell clones that responded only to synthetic peptides GP-S55S and Rt-S55S but not to the parent BP adoptively transferred delayed-type hypersensitivity but not disease in Lewis rats. The same clones failed to respond to either the S67 or the S75-89 sequences. These results demonstrate that the encephalitogenic Rt-S55S sequence houses a minimum of two T cell epitopes with differing specificities and functions. One epitope is immuno-dominant and resembles the encephalitogenic region of the intact BP molecule. The second non-encephalitogenic epitope is restricted to the S55S sequences and is not shared by the parent BP, the S67, or the S75-89 sequences. Both types of Rt-S55S-specific clones differ in fine specificity from encephalitogenic clones selected from GP-BP immunized rats, thus indicating that uniformity of T cell recognition of the encephalitogenic epitope is not an absolute condition for T cells to be encephalitogenic.