Response of rat encephalitogenic T lymphocyte lines to synthetic peptides of myelin basic protein

T lymphocyte lines and clones selected from Lewis rats immunized with guinea pig basic protein (GP-BP) proliferate and acquire the ability to transfer experimental autoimmune encephalomyelitis (EAE) after activation by the 68-88 peptide of GP-BP in concert with autologous I-A major histocompatibility antigens. In order to evaluate the amino acid sequence required for activation, encephalitogenic T lymphocytes were stimulated with synthetic peptides representing the 69-89, 69-84, 72-84, and 75-84 sequence of GP-BP. The three longest peptides, but not the 75-84 peptide, induced encephalitogenic lines and clones to proliferate and to transfer clinical EAE; none of the peptides, however, could activate T cell lines of a different epitope specificity. The 69-89 sequence was the most efficient of the synthetic peptides, inducing optimal stimulation comparable to GP-BP at 10 micrograms/ml. The 69-84 and 72-84 sequences induced comparable levels of stimulation at 250 micrograms/ml, but the 75-84 sequence was not active at any concentration. These results show that the 11 amino acids representing the 72-84 sequence of GP-BP are sufficient to trigger encephalitogenic T cell activity, and suggest that the 85-89 sequence may stabilize the conformation of the encephalitogenic epitope. The close association observed between proliferation and EAE transfer activities, induced in highly purified T cell populations using synthetic peptides, suggests that these two functional properties of T cells result from a common activation pathway involving a single T cell receptor specificity.     

T cell receptor Vβ gene usage in the recognition of myelin basic protein by cerebrospinal fluid- and blood-derived T cells from patients with multiple sclerosis

Because of its proximity to the central nervous system, the cerebrospinal fluid (CSF) represents an important source of T cells that potentially could mediate putative autoimmune diseases such as multiple sclerosis (MS). To overcome the low CSF cellularity, we evaluated culture conditions that could expand CSF T cells, with a focus on the expression of T-cell receptor Vβ genes utilized by T cells specific for the potentially encephalitogenic autoantigen myelin basic protein (BP). Expansion of “activated” CSF cells with IL-2/IL-4 plus accessory cells optimally retained BP-responsive T cells that over-expressed Vβ1, Vβ2, Vβ;5, or Vβ;18, compared to expansion using supernatants from PHA-stimulated blood cells, or anti-CD3 antibody that led to different V gene bias and rare reactivity to BP. Sequential evaluation of paired CSF and blood samples from a relapsing remitting MS patient indicated that BP-reactive T cells were present in CSF during the period of clinical activity, and the pattern of BP recognition in CSF was partially reflected in blood, even after CSF reactivity had dissipated during remission. Over-expressed Vβ genes were not always constant, however, since in three sequential evaluations of a chronic progressive MS patient, Vβ genes over-expressed in the first BP-reactive CSF switched to a different Vβ gene bias that was present in the second and third CSF samples. Blood samples reflected each pattern of CSF Vβ gene bias, but retained the initial bias for at least 4 months after its disappearance from CSF. These data indicate that selective expansion of IL-2/Il-4-responsive CSF cells favors growth of the BP-reactive subpopulation, and, in a limited number of patients studied, reflected clinical disease activity. In comparison, blood T cells provided a partial but longer lasting reflection of the CSF BP reactivity and Vβ gene bias. © 1994 Wiley-Liss, Inc.     

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.     

Experimental allergic encephalomyelitis: Modulation by intraventricular injection of myelin basic protein

Antigen-induced suppression and therapy of experimental allergic encephalomyelitis in Lewis rats was studied using guinea pig myelin basic protein administered either intravenously or intraventricularly. A small intraventricular dose of basic protein was effective when given shortly before the onset of clinical signs (suppression) as well as when given after the disease (therapy). In contrast, the same amount of basic protein administered intravenously was effective only in the therapy of disease.     

Pathogenic and non-pathogenic T lymphocytes specific for the encephalitogenic epitope of myelin basic protein: Functional characteristics and vaccination properties

Activated CD4⁺ T lymphocytes specific for myelin basic protein (MBP) can cause experimental autoimmune encephalomyelitis (EAE) upon their inoculation into syngeneic recipients. In Lewis rats, most of the pathogenic T cell clones that develop following immunization with MBP are reactive against the 72–84 amino acid sequence of MBP, the major encephalitogenic region for Lewis rats. In this study, some MBP-specific T cell clones were found to be non-pathogenic, in spite of their strong reactivity against the encephalitogenic epitope. One of these non-pathogenic clones, designated Znp, and an encephalitogenic clone, Z1a-p, were derived from Z1a encephalitogenic line cells. These subclones were compared for epitope specificity, T cell receptor variable gene expression and for various functional activities, in order to delineate properties crucialof pathogenicity. The Z1a-p and Znp cells expressed comparable levels of the T cell receptor genes and shared strong reactivity against the 72–84 epitope of MBP. The pathogenic Z1a-p cells displayed MBP-specific cytolytic activity in vitro, provided an in-vivo ‘help’ for elicitation of MBP-specific antibodies, mediated a delayed type hypersensitivity (DTH) response to MBP, caused EAE and vaccinated against the disease, thus demonstrating that a single CD4⁺ T cell clone is capable of eliciting various functions. The non-pathogenic Znp cells could also carry out most of these various functions, but failed to mediate a DTH response to MBP in normal animals. However, when inoculated into sublethally (650 R) irradiated syngeneic recipients, the Znp cells became highly pathogenic and mediated DTH response to MBP. Local irradiation of the recipient facilitated a DTH response to MBP in the irradiated ear, indicating that Znp cells are equipped with the effector mechanisms required for pathogenicity, and that their failure to cause disease may be accounted for by their inability to migrate into extravascular target tissue. Similar data were obtained with an independently isolated non-pathogenic clone, LB-3, specific for the encephalitogenic epitope of MBP. The ability of these non-pathogenic cells to vaccinate against EAE mediated by pathogenic cells raises the possibility that such non-pathogenic cells may play a role in triggering downregulation of pathogenic T cells.     

Myelin basic protein specific T-helper cells induce experimental anterior uveitis

Immunopathological changes in the eyes were examined in Lewis rats after active and passive induction of experimental autoimmune encephalomyelitis (EAE) with myelin basic proteins (MBP) at various stages of EAE. The onset of anterior uveitis (AU) coincided with hind limb paralysis, but uveitis persisted after clinical signs of EAE had subsided. A mild form of uveitis was characteristic for the majority of rats. The changes within the iris and ciliary body consisted of an accumulation of inflammatory cells lining the anterior surface of iris, the trabecular meshwork, and, in some cases, within the ciliary body and the aqueous humor. A similar histopathological picture was observed when rats were injected with the secondary encephalitogenic determinant for Lewis rats, MBP peptide 87–99. Flow cytometry analysis of T cells from the anterior segment of the inflamed eyes after immunization with MBP revealed the presence of CD4⁺ cells exclusively expressing Vβ8.2 and OX-40 markers. Our data suggest that MBP are encephalitogenic and uveitogenic in Lewis rats and that the Vβ8.2-positive T cells in the eye represent encephalitogenic T cells. Many of those T cells were distributed in the iris and the anterior chamber. These findings indicate that these MBP-specific T cells may play a critical role in EAE as well as in AU. © 1996 Wiley-Liss, Inc.     

Human T lymphocytes specific for the immunodominant 83–99 epitope of myelin basic protein: Recognition of golli MBP HOG 7

Myelin basic protein (MBP) is a candidate auto-antigen in the disease multiple sclerosis. Although MBP was thought to be sequestered behind the blood-brain barrier, isoforms of MBPs have recently been demonstrated in lymphoid tissues. These isoforms, termed golli MBPs, contain sequences that are shared with “classic” MBP within the CNS. In the present study, we have determined that epitopes within golli MBP isoforms may be recognized by human T lymphocyte clones specific for classic MBP. Ten of 12 T-cell clones recognized golli MBP. Although 11 clones were specific for the immunodominant 83–99 sequence, the clones differed with respect to human leukocyte antigen (HLA) restriction, T-helper phenotype, cytolytic activity, and T-cell receptor usage. Greater responses to classic MBP than to golli MBP suggested a difference in the ability of the two proteins to be processed and to present epitopes therein. These data advance the hypothesis that golli MBP sequences expressed within lymphoid tissues may be recognized by classic MBP-specific T lymphocytes during central or peripheral tolerance. © 1996 Wiley-Liss, Inc.     

T cell responses to myelin basic protein in experimental autoimmune encephalomyelitis-resistant BALB/c mice

In strains of mice that are susceptible to experimental autoimmune encephalomyelitis (EAE), cloned CD4⁺ T cells reactive with autologous myelin basic protein (MBP) have been shown to cause disease when transferred to naive syngeneic recipients. Recent reports indicate that under particular experimental conditions, ‘resistant’ strains of mice can also develop EAE, although cloned cells have not been isolated and characterized. An analyis of the characteristics of a panel of MBP-specific T cells and the antigen presenting capability of CNS-derived cells obtained from the resistant strain BALB/c is presented here. The data demonnstrate that immunization of EAE-resistant BALB/c mice results in the activation of a heterogeneous group of T cells reactive with autologous MBP. Both peripheral antigen presenting cells, as well as microglia isolated from brains of BALB/c mice, are capable of stimulating these cloned MBP-specific T cells to proliferate. When optimally activated in vitro and then injected in vivo into syngeneic BALB/c recipients, three clones studied induced severe cachexia, resulting in loss of up to 35% of body weight before death. Two of the clones also induced clinical and histological EAE, while the third induced only occasional histological evidence of disease. Differences in epitope recognition, T cell receptor usage, cytokine profiles or regulatory mechanisms of self tolerance, may play important roles in preventing potentially destructive autoimmune reactions by these T cells capable of recognizing autologous myelin in the central nervous system.     

T cell immunity to myelin basic protein induces anterior uveitis in Lewis rats

Uveitis of unknown etiology is known to occur in association with various systemic disorders. We now report that anterior uveitis (AU) can be produced by T cell immunity to myelin basic protein (BP) and accompanies experimental autoimmune encephalomyelitis (EAE). EAE with AU was induced in Lewis rats by immunization to BP in CFA or by immunization to various BP peptides including the encephalitogenic 71–90 peptide. Slit-lamp biomicroscopy of BP-immunized Lewis rats revealed AU, characterised by inflammation of the iris, in 73% of the eyes. The onset of AU in actively immunized rats varied between days 12 and 26, often appearing after spontaneous remission of the paralysis, the hallmark of EAE. The course of AU was progressive, affecting more than 50% of the surface of the iris in 16 of 29 diseased eyes. Like the paralysis, the AU was self-limiting: within 2 weeks the disease remitted. In addition, AU could be adoptively transferred to naive and irradiated rats by a T cell clone specific for BP peptide 71–90. The present observations are compatible with the idea that AU may be triggered by BP-reactive T cells. The myelinated nerves present in the iris have been shown to contain BP. However, these peripheral nerves would now appear to be the only peripheral nerves susceptible to acute EAE.     

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.     

一种新的基质金属蛋白酶抑制剂ONO-4817对实验性自身免疫性脑脊髓炎的治疗作用

目的　探讨一种新合成的含氧肟酸的基质金属蛋白酶 ( MMP)抑制剂 ONO-481 7对实验性自身免疫性脑脊髓炎 ( EAE)的治疗效果。方法　给 EAE大鼠口服 ONO-481 7,观察临床症状、T淋巴细胞增殖以及血清肿瘤坏死因子 ( TNF) -α水平。结果　 ONO-481 7能显著改善 EAE临床症状 ( P <0 .0 1 ) ,同时明显抑制 T淋巴细胞增殖 ( P <0 .0 1 ) ,显著降低大鼠血清 TNF-α水平 ( P <0 .0 5 )。结论　研究表明 ,ONO-481 7通过抑制 MMPs活性、T淋巴细胞增殖和减少 TNF-α生成 ,进而能显著减轻血脑屏障 ( BBB)的破坏 ,又可抑制炎细胞浸润和髓鞘破坏 ,从而有效缓解 EAE。     

Autoantibodies to myelin basic protein are not present in the serum and CSF of MS patients

Myelin basic protein (MBP) is one of the main constituents of the CNS myelin sheaths, and an autoimmune response directed against MBP may be crucial in the demyelination process in patients with multiple sclerosis (MS). In this study sera and cerebrospinal fluid (CSF) from 25 MS patients, 25 patients with other neurological diseases and 16 healthy controls were examined for antibodies against MBP by using radio immunoblot, western blot, radio immunoassay and enzyme-linked immunosorbant assay. No evidence for the presence of antibodies to MBP was found in sera or CSFs in either the MS patients, or in the control groups tested.     

FK506 and a nonimmunosuppressant derivative reduce axonal and myelin damage in experimental autoimmune encephalomyelitis: neuroimmunophilin ligand-mediated neuroprotection in a model of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) in which demyelination and axonal loss result in permanent neurologic disability. We examined the neuroprotective property of the immunosuppressant FK506 (tacrolimus), FK1706 (a nonimmunosuppressant FK506 derivative) and cyclosporin A (CsA) in a chronic relapsing experimental autoimmune encephalomyelitis (EAE) model of MS. Female SJL/J mice were immunized by subcutaneous (s.c.) injection with proteolipid protein 139-151 peptide in complete Freund's adjuvant. At the onset of paralysis, 12-14 days after immunization, mice received daily s.c. injections of FK506 (0.2, 1, and 5 mg/kg), FK1706 (5 mg/kg), CsA (2, 10, and 50 mg/kg), saline or vehicle (30% dimethylsulfoxide) for 30 days. FK506 (at a dose of 5 mg/kg) reduced the severity of the initial disease and suppressed relapses. FK1706 did not significantly alter the clinical course and CsA (at a dose of 50 mg/kg) lessened the severity of the initial episode of EAE but did not alter relapses. In the thoracic spinal cord, FK506 (5 mg/kg), FK1706 (5 mg/kg), and CsA (50 mg/kg) significantly (P < 0.001) reduced the extent of damage in the dorsal, lateral, and ventral white matter by a mean of up to 95, 68, and 30%, respectively. A nonimmunosuppressant dose of FK506 (0.2 mg/kg) also significantly (P < 0.001) reduced the extent of damage in the spinal cord by a mean of up to 45%. Other dosages of these compounds were ineffective. FK506 markedly protects against demyelination and axonal loss in this MS model through immunosuppression and neuroprotection.     

Phenotype and function of hematopoietic-derived cells in the CNS of SCID mouse-lewis rat bone marrow chimeras

Severe combined immunodeficient (SCID) mice previously transplanted with Lewis rat hematopoietic cells (SCID mouse-Lewis rat chimeras) developed experimental autoimmune encephalomyelitis (EAE) following injection with myelin basic protein (BP)-specific Lewis rat T lymphocytes. Rat T cells did not cause EAE in non-chimeric SCID mice. Thus, in addition to BP-specific rat T cells, transplanted rat hematopoietic cells were involved in the development of EAE in SCID mice. In order to examine the role of hematopoietic rat cells in the development of EAE, chimeras were constructed in SCID mice by transplanting 40 × 10⁶ T cell-depleted adult Lewis rat bone marrow cells. Single cell suspensions of brain, blood and spleen from chimeric mice were phenotyped by monoclonal antibody staining specific for mouse or rat cellular differentiation markers at 2 week intervals. Brain cells from chimeric mice were also evaluated for the presence of rat antigen-presenting cells (APC). Four and six weeks after hematopoietic cell transfer, mouse brain contained rat cells expressing the phenotypic markers (CD45+, CD11b/c+) of CNS antigen-presenting cells (APC). Six weeks after hematopoietic cell transfer, rat cells populating the CNS of chimeras were shown to function as APC, stimulating BP-specific Lewis rat T lymphocytes in vitro. © 1996 Wiley-Liss, Inc.     

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.     

T-cell hybridoma specific for myelin oligodendrocyte glycoprotein-35-55 peptide produced from HLA-DRB1*1501-transgenic mice

The goal of this study was to establish an unlimited and standardized source of humanized myelin peptide-specific T cells for in vitro testing of biological function. Thus, we perpetuated myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide-specific T cells obtained from immunized HLA-DRB1*1501-transgenic (Tg) mice by somatic fusions with BW5147 thymoma cells or BW5147 T-cell receptor (TCR) alpha(-)beta(-) variant (BW5147 variant) cells. The resulting T-cell hybridomas responded strongly to both mouse MOG-35-55 (42S) and human MOG-35-55 peptide (42P), regardless of which peptide was used for initial immunization, and were DRB1*1501 restricted. The MOG-35-55-reactive T-cell hybridomas were CD3(+)CD4(+)CD8(-) and expressed intracellular Th1 cytokines upon concanavalin A stimulation. Clones from either human MOG-35-55- or mouse MOG-35-55-selected hybridomas uniquely expressed the TCR BV8 gene in combination with AV17 and AV11 genes. V gene analyses confirmed the expression of TCR AV1, AV11, AV16, BV1, and BV5 gene segments in the widely used fusion partner BW5147 and demonstrated deletion of TCR AV1, AV11, and BV1 in the BW5147 variant. T-cell hybridomas were positively stained with anti-TCR beta-chain antibody on the cell surface, whereas neither BW5147 nor its variant had positive TCR surface expression. For functional application, we found that a monomeric form of the human HLA-DR2-derived recombinant T-cell receptor ligand (RTL) covalently linked to human MOG-35-55 peptide specifically inhibited proliferation of a hybridoma clone selected with human MOG-35-55 but not a different hybridoma clone selected with myelin basic protein. The RTL-induced inhibition in vitro of the human MOG-35-55 peptide-specific hybridoma reflected the ability of the RTL to inhibit experimental autoimmune encephalomyelitis induced by human MOG-35-55 peptide in HLA-DR2 transgenic mice. Thus, the MOG-35-55 peptide-specific T-cell hybridoma from DR2-Tg mice represents a novel humanized T-cell reagent useful for standardized biological screening of both DR2-restricted stimulation and RTL-dependent inhibition of response to human MOG-35-55 peptide.     

Recent advances in the immunopathology of experimental autoimmune encephalomyelitis: With special reference to cytokine production in the central nervous system

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease that can be induced by immunization with encephalitogenic antigens such as myelin basic protein. Recent in vitro studies have demonstrated that cytokines play an important role in immune reactions in the central nervous system (CNS), suggesting that cytokines released by infiltrating cells and glial cells may contribute to the pathogenesis of EAE. In this review, we focus on the interactions between infiltrating cells and brain cells during the inflammatory process in EAE and discuss the roles of cytokines in the CNS. After immunization with proper myelin antigens, encephalitogenic T cells increase in number and infiltrate the CNS parenchyma via the subarachnoid space or the blood vessels. Once inflammatory cells infiltrate the CNS, microglia and astrocytes are activated, and some of these cells proliferate in response to cytokines released by infiltrating cells. Following this, activated microglia present antigens to induce T cell proliferation and cytokine production. In contrast, astrocytes induce T cell unresponsiveness, probably due to a lack of costimulatory signals. Furthermore, infiltrating T cells are the main producers of Th1 cytokines and are involved in T cell-brain cell interactions. This cascade of events indicates that immune reactions take place in the CNS, although the CNS has previously been considered to be an immunologically privileged site. Based on these findings, we also discuss the feasibility of using various cytokines to stimulate the immunomodulation of brain inflammation as a treatment for autoimmune demyelinating diseases.     

The proximal peripheral nervous system is a major site of demyelination in experimental autoimmune encephalomyelitis induced in the Lewis rat by a myelin basic protein-specific T cell clone

Experimental autoimmune encephalomyelitis (EAE) was induced in the Lewis rat by the passive transfer of a cytotoxic CD4⁺ T cell clone specific for the 72–89 peptide of guinea-pig myelin basic protein (MBP). Histological studies on rats with neurological signs showed that inflammation was present in the proximal peripheral nervous system (PNS), namely the spinal roots, as well as in the central nervous system (CNS). The main sites of demyelination were the spinal roots in the PNS, and the spinal cord root entry and exit zones in the CNS. The major involvement of the proximal PNS in autoimmune disease directed at MBP is in marked contrast to EAE induced by immunisation with myelin proteolipid protein, where the inflammation and demyelination are restricted to the CNS. These findings may have implications for the human inflammatory demyelinating diseases including multiple sclerosis, in which MBP is a putative target antigen.     

Multiple sclerosis: occurrence of myelin basic protein peptide-reactive T cells in healthy family members

Genetic factors influence the susceptibility to multiple sclerosis (MS). This disease is accompanied by augmented T cell responses to CNS myelin components such as myelin basic protein. To evaluate the familial occurrence of such T cell autoreactivity, we have studied 12 MS families including 37 healthy first-degree relatives for occurrence of numbers of interferon-gamma (IFN-γ) secreting cells among blood mononuclear after culture in presence of myelin basic protein (MBP), eight synthetic MBP peptides and the control antigen acetylcholine receptor (AChR). There were no differences between MS patients and healthy family members regarding frequencies of autoreactive T cells recognizing MBP, the eight different MBP peptides or AChR. None of the MBP peptides predominated as T cell antigen among the MS patients or their unaffected family members. In some families the highest number of MBP peptide reactive T cells were found among unaffected family members. No correlation was observed between numbers of MBP or MBP peptide reactive T cells in various subjects and their HLA-DR-DQ phenotypes. In conclusion, this study has revealed the presence of MBP and MBP peptide reactive T cells of similar frequencies in MS patients and their healthy family members.     

Experimental allergic encephalomyelitis: Characterization of serum factors causing demyelination and swelling of myelin

Serum factors in rabbits with white matter-induced experimental allergic encephalomyelitis (WM-EAE) were studied with respect to their role in demyelination in vitro in organotypic central nervous system (CNS) tissue cultures and in vivo in the myelinated retina of the rabbit eye. By absorption with staphylococcal protein A, IgG was quantitatively separated from the other serum proteins. No IgG was demonstrable in the absorbed IgG-depleted sera by Ouchterlony double diffusion, immunoelectrophoresis and SDS-polyacrylamide gel electrophoresis. Both the IgG-depleted WM-EAE sera and the IgG fractions had complement-dependent demyelinating activity on CNS cultures, and both contained immunoglobulin binding to myelin and oligodendroglia of the cultures, as demonstrated by an immunoperoxidase technique. However, only the purified IgG fractions in the absence of complement induced swelling of myelin and proliferation of oligodendroglial processes with redundant myelin in tissue cultures. The IgG-depleted complement-inactivated WM-EAE sera produced no morphological changes. In the rabbit eye model, antibody-dependent cell-mediated demyelination was observed only with the IgG fractions but not with the IgG-depleted EAE sera. No oligodendroglial proliferation occurred. These studies demonstrate for the first time that in CNS cultures, non-IgG immunoglobulins as well as IgG mediate complement-dependent demyelination and that these bind to myelin and oligodendrocytes, whereas only IgG causes myelin swelling and oligodendrocyte proliferation.