A conformational study of the human and rat encephalitogenic myelin oligodendrocyte glycoprotein peptides 35-55

Myelin oligodendrocyte glycoprotein (MOG), is considered an important central-nervous system-specific target autoantigen for primary demyelination in autoimmune diseases like multiple sclerosis. We have recently demonstrated that MOG or its derived peptide, MOG-(35-55)-peptide, are able to produce in animals, clinicopathologic signs that mimic multiple sclerosis. The rat MOG sequence spanning amino acids 35-55 [rMOG-(35-55)-peptide] differs from the human sequence [hMOG-(35-55)-peptide] by a single amino acid substitution, i.e. Pro42-->Ser. Mice injected with rMOG-(35-55)-peptide showed severe inflammation and demyelination throughout the central nervous system but, interestingly, mice injected with hMOG-(35 -55)-peptide showed only a few foci of mild inflammation with no demyelination. Circular dichroism and nuclear magnetic resonance spectroscopy have been used to structurally characterise the bioactive peptides hMOG-(35-55)-peptide and rMOG-(35-55)-peptide. In 0.1 M K2HPO4/KOH, 90% H2O/D2O solutions, these derived peptides have been shown, by NMR spectroscopy, to adopt detectable levels of short-range structure in equilibrium with unfolded conformers. On addition of 2,2,2-trifluoro-(2H3)ethanol, rMOG-(35-55)-peptide and hMOG-(35-55)-peptide adopt folded structures which have nuclear Overhauser enhancements characteristic of a poorly defined alpha-helix over residues 44-51. There are some indications of secondary structure also evident in the N-terminal region of rMOG-(35-55)-peptide. CD spectroscopy has revealed that in aqueous solution both peptides are unfolded but in 2.2.2-trifluoroethanol and, at micellar concentrations of sodium dodecyl sulfate, rMOG-(35-55)-peptide and, to a lesser extent, hMOG-(35-55)-peptide adopt helical conformations. In contrast, at non-micellar concentrations of SDS rMOG-(35-55)-peptide and hMOG-(35-55)-peptide adopt, according to CD spectroscopy, a beta-structure indicating that the peptides change conformation depending on the microenvironment of the amino acids.

Myelin oligodendrocyte glycoprotein: a novel candidate autoantigen in multiple sclerosis

Myelin oligodendrocyte glycoprotein (MOG) is a member of the immunoglobulin superfamily expressed exclusively in central nervous system (CNS) myelin. While the function of MOG is unknown, a number of studies have shown that immune responses to MOG contribute to the autoimmune-mediated demyelination seen in animals immunized with whole CNS tissue. This paper summarizes our recent studies, which unequivocally demonstrate that MOG by itself is able to generate both an encephalitogenic T cell response and an autoantibody response in Lewis rats and in several strains of mice. In Lewis rats the injection of both native MOG and MOG35-55 peptide produces a paralytic relapsing-remitting neurological disease with extensive plaque-like demyelination. The antibody response to MOG35-55 was highly restricted, as no reactivity to either other MOG peptides or myelin proteins could be detected. Fine epitope mapping showed that antibody from serum and cerebrospinal fluid of injected rats reacted strongly to MOG37-46, which is contiguous to the dominant T cell epitope contained within MOG44-55. NOD/Lt and C57BL/6 mice were also susceptible to severe neurological disease following injection with recombinant MOG or MOG35-55 peptide, indicating that this specific CNS autoantigen, or some of its determinants, can induce a pathogenic response across animal species. Severe paralysis and extensive demyelination were seen in both strains, but NOD/Lt mice experienced a chronic relapsing disease whereas C57BL/6 mice had a chronic non-remitting disease. Moreover, transfer of MOG35-55 T cells into naive NOD/Lt mice also produced severe neurological impairment as well as histological lesions. These results emphasize that a synergism between a T cell-response and anti-MOG antibodies may be important for the development of severe demyelinating disease. This, together with our demonstration that there is a predominant T cell response to MOG in patients with multiple sclerosis, clearly indicates that MOG is probably an important target autoantigen in this disease.

Regulation of myelin oligodendrocyte glycoprotein in different species throughout development

The assembly and function of central nervous system (CNS) myelin requires the coordinated expression of several myelin-specific proteins, including myelin oligodendrocyte glycoprotein (MOG). Despite the recent cloning of MOG, the function of this molecule is still unknown. Because MOG is a late marker of oligodendrocyte maturation and is exclusively expressed in the CNS on the outermost lamellae of the myelin membrane, it is possible that this molecule plays an important role in the control and maintenance of myelination. Furthermore, as a member of the immunoglobulin superfamily that carries the L2/HNK-1 epitope, it has also been suggested that MOG is involved in cell-cell interaction, perhaps functioning as an adhesive molecule for bundles of nerve fibres. In order to further delineate the role of MOG throughout development we have analysed, by immunoblotting, the developmental appearance and accumulation pattern of MOG in the CNS of three mammalian species. We have also purified MOG to homogeneity from five different species including rat, guinea pig, bovine, monkey and human. Immunoblotting revealed two major MOG bands at 28 and 55 kD in all species. The 55 kD band appears to be a dimer of the lower band although treatment with 2-mercaptoethanol or EDTA failed to abolish it. Purified MOG from all species also displayed faint reactivity with bands at 36, 48 and 78 kD. While the 78 kD band may represent a trimer of MOG, the identity of the other bands remains unknown. Developmental studies in mouse, rat, guinea pig and bovine showed at as for other myelin proteins, MOG displayed a caudorostral gradient of expression, appearing in the spinal cord before the brain. The sensitivity of the detection system used here allowed us to detect MOG protein earlier than in previous reports such that its presence was clearly demonstrated in the CNS of mice and rats at 14 and 10 days after birth, respectively. Analysis of MOG expression in a novel transgenic mouse model that has both delayed and reduced myelination revealed that, like other myelin proteins, MOG expression was delayed compared with normal littermates. These results demonstrate that the expression of MOG is similar in all species and is regulated in a manner consistent with other myelin-specific proteins.

Binding of complement component Clq to myelin oligodendrocyte glycoprotein: a novel mechanism for regulating CNS inflammation

Myelin oligodendrocyte glycoprotein (MOG) is a myelin-specific protein restricted to the central nervous system (CNS). While MOG is considered a putative autoantigen in MS, its function(s) in myelin is unknown. As CNS myelin is able to activate the classical complement pathway, it must contain a Clq-binding/activating protein but the identity of this protein has not been reported. The data in this paper clearly demonstrate that MOG specifically binds Clq in a dose-dependent and saturating manner. This calcium-dependent interaction is mediated by the extracellular immunoglobulin-like domain of MOG. This MOG domain contains an amino acid motif similar to the core Clq-binding sequence previously identified in IgG antibodies. Purified MOG also inhibited the antibody-dependent lysis of RBC by complement. Taken together, these results demonstrate that MOG binds Clq near the IgG binding site and may be the protein responsible for complement activation in myelin. This direct interaction between a myelin-specific protein and Clq has significant implications for CNS inflammation and could be particularly important in demyelinating diseases such as multiple sclerosis.

Antibody response in Lewis rats injected with myelin oligodendrocyte glycoprotein derived peptides

Previous studies from our laboratory have demonstrated a predominant response to myelin oligodendrocyte glycoprotein (MOG) in patients with multiple sclerosis (MS) and showed that this molecule is able to induce in Lewis rats a chronic relapsing MS-like disease with extensive demyelination. To further study the possibility that MOG is a primary target antigen in MS, we have begun to investigate the encephalitogenicity and antibody response of different sequences of the extracellular domains of MOG in Lewis rats. We report that none of the synthetic peptides encompassing the MOG amino acid sequences 1-21, 67-87, 104-117 and 202-218 were encephalitogenic. In contrast, a single injection of MOG35-55 was able to induce severe neurological signs associated with inflammation and demyelination. All rats injected with MOG peptides 1-21, 35-55, 67-87 and 202-218 developed a high level of antibodies to their respective immunizing peptides as detected by ELISA and immunoblotting. Although all MOG peptide antisera reacted with immunoblots of native MOG separated under reducing conditions, only anti-MOG35-55 and anti-MOG202-218 antibodies reacted to native MOG, when tested under nonreducing conditions. These results indicate that the MOG35-55 peptide, which is found in the extracellular Ig V-like domain of MOG, is not only an encephalitogenic epitope but could also be an important determinant for initiating antibody-mediated demyelination. As indicated by the absence of reactivity to the other MOG peptides tested, as well as other central nervous system myelin proteins including myelin basic protein and proteolipid protein, the antibody response produced by MOG peptides is highly restricted.

Immunosusceptibility genes in rheumatoid arthritis

The polygenic predisposition to RA is conferred particularly by disease susceptibility sequences in the HVR3 of HLA DRB1 present in those subtypes of DR4 and DR1 that are associated with RA. The aim of this study was to examine predisposing interactions between genes encoding HLA and immunoglobulin molecules. Accordingly, we compared the genetic background of 114 Australian patients with RA with that of Australian controls of similar ethnic background. We identified HLA-A, B, and DR phenotypes serologically, HLA-DR, DQ alleles, and subtypes of DR4 by DNA typing, and Gm allogenotypes and immunoglobulin switch region polymorphisms by RFLP. For the subjects with RA, we confirmed previously reported observations that included an excess of females, 71%, a high frequency of HLA types DR4 or DR1 of 77% versus controls 47%, and a high frequency of the HVR3 susceptibility sequences of 76%, with 24% homozygous, and 52% heterozygous for the sequences. We observed other genetic correlations in RA that included increases in frequencies of DR4 in males, DR1 in females, the class I specificity HLA-B27 overall but more particularly in females, 24% in females, versus 5% of controls, HLA-DQB1*0302 (DQ8) in DR4*0401-positive patients, and the Gm allogenotype 1,2,3;23 +/- ; 5,10, 15% of patients versus 4% of controls. Examination of switch region genes gave no evidence of differences in the polymorphisms distributions. Thus, the major genetic risks for RA that are conferred by female gender and the HVR3 of HLA DRB1 are modulated by interactions between gender and HLA class I and class II alleles, and the Gm allogenotype.

IFN-gamma plays a critical down-regulatory role in the induction and effector phase of myelin oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis

129/Sv mice are resistant to induction of experimental autoimmune encephalomyelitis (EAE) induced with myelin oligodendrocyte glycoprotein peptide (MOG35-55). Mice of this strain lacking the gene coding for the ligand-binding chain of the IFN-gamma receptor develop EAE with high morbidity and mortality. Spleen cells from sensitized IFN-gammaR-/- mice proliferated extensively when stimulated with MOG peptide in culture and produced high levels of IFN-gamma and TNF but no detectable IL-4. Transfer of spleen cells from sensitized IFN-gammaR-/- mice produced EAE in both IFN-gammaR+/+ and IFN-gammaR-/- recipients. Disease was severe in IFN-gammaR-/- recipients and mortality high (77%). Surviving mice remained moribund until termination of the experiments. IFN-gammaR+/+ recipients developed disease of equal severity, but with no mortality, and recovered significantly. These results indicate that IFN-gamma is not essential for the generation or function of anti-MOG35-55 effector cells but does play an important role in down-regulating EAE at both the effector and induction phase of disease.

IFN-gamma plays a critical down-regulatory role in the induction and effector phase of myelin oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis

129/Sv mice are resistant to induction of experimental autoimmune encephalomyelitis (EAE) induced with myelin oligodendrocyte glycoprotein peptide (MOG35-55). Mice of this strain lacking the gene coding for the ligand-binding chain of the IFN-gamma receptor develop EAE with high morbidity and mortality. Spleen cells from sensitized IFN-gammaR-/- mice proliferated extensively when stimulated with MOG peptide in culture and produced high levels of IFN-gamma and TNF but no detectable IL-4. Transfer of spleen cells from sensitized IFN-gammaR-/- mice produced EAE in both IFN-gammaR+/+ and IFN-gammaR-/- recipients. Disease was severe in IFN-gammaR-/- recipients and mortality high (77%). Surviving mice remained moribund until termination of the experiments. IFN-gammaR+/+ recipients developed disease of equal severity, but with no mortality, and recovered significantly. These results indicate that IFN-gamma is not essential for the generation or function of anti-MOG35-55 effector cells but does play an important role in down-regulating EAE at both the effector and induction phase of disease.

Analysis of the fine B cell specificity during the chronic/relapsing course of a multiple sclerosis-like disease in Lewis rats injected with the encephalitogenic myelin oligodendrocyte glycoprotein peptide 35-55

We have recently shown that a single injection of myelin oligodendrocyte glycoprotein (MOG), or the MOG35-55 peptide, produces a relapsing-remitting neurologic disease with extensive plaque-like demyelination. Given the features that this new autoimmune demyelinating model has in common with the clinicopathologic manifestations of multiple sclerosis, we have examined the Ab reactivity to native MOG and MOG35-55 peptide during the course of the disease in Lewis rats. Following immunization with MOG35-55, varied clinical symptoms were observed; these included hind and foreleg paralysis and various degrees of balance impairment. Disease progression also varied: 3 out of 21 animals had a single mild disease episode; 4 out of 21 had a mild relapsing-remitting disease; and 14 out of 21 had severe relapsing-remitting disease. Ab reactivity to MOG35-55 and native MOG was first detected in all rats 4 wk postimmunization and persisted throughout the 12 wk of observation. The Ab response was highly restricted with no reactivity to other peptides encompassing different extracellular segments of MOG. Fine epitope mapping showed that Ab from serum and cerebrospinal fluid of injected rats reacted strongly to MOG37-46 and to a lesser extent to MOG43-50. Although significant levels of anti-MOG Abs appeared necessary for the development of demyelinating lesions, their presence in blood and cerebrospinal fluid alone was not sufficient to produce severe clinical symptoms. These results demonstrate that the MOG35-55 peptide is highly encephalitogenic and can induce strong T and B cell responses. It is probably the complex interaction between these T and B cells that determines the severity of disease in individual rats.

Analysis of the fine B cell specificity during the chronic/relapsing course of a multiple sclerosis-like disease in Lewis rats injected with the encephalitogenic myelin oligodendrocyte glycoprotein peptide 35-55

We have recently shown that a single injection of myelin oligodendrocyte glycoprotein (MOG), or the MOG35-55 peptide, produces a relapsing-remitting neurologic disease with extensive plaque-like demyelination. Given the features that this new autoimmune demyelinating model has in common with the clinicopathologic manifestations of multiple sclerosis, we have examined the Ab reactivity to native MOG and MOG35-55 peptide during the course of the disease in Lewis rats. Following immunization with MOG35-55, varied clinical symptoms were observed; these included hind and foreleg paralysis and various degrees of balance impairment. Disease progression also varied: 3 out of 21 animals had a single mild disease episode; 4 out of 21 had a mild relapsing-remitting disease; and 14 out of 21 had severe relapsing-remitting disease. Ab reactivity to MOG35-55 and native MOG was first detected in all rats 4 wk postimmunization and persisted throughout the 12 wk of observation. The Ab response was highly restricted with no reactivity to other peptides encompassing different extracellular segments of MOG. Fine epitope mapping showed that Ab from serum and cerebrospinal fluid of injected rats reacted strongly to MOG37-46 and to a lesser extent to MOG43-50. Although significant levels of anti-MOG Abs appeared necessary for the development of demyelinating lesions, their presence in blood and cerebrospinal fluid alone was not sufficient to produce severe clinical symptoms. These results demonstrate that the MOG35-55 peptide is highly encephalitogenic and can induce strong T and B cell responses. It is probably the complex interaction between these T and B cells that determines the severity of disease in individual rats.

Characterization of cDNA and genomic clones encoding human myelin oligodendrocyte glycoprotein

Myelin oligodendrocyte glycoprotein (MOG) is a transmembrane protein expressed only in the CNS and is a possible target autoantigen in multiple sclerosis (MS). To further study the association of MOG with MS, we have characterized cDNA and genomic clones encoding human MOG. The human MOG cDNA, like its rodent and bovine counterparts, encodes a mature protein containing an Ig-like domain, followed by two potential membrane-spanning regions. The intron-exon boundaries of the human MOG gene were mapped and revealed that the signal peptide is encoded by the first exon, the Ig-like domain of MOG is encoded on the second exon, whereas the remainder of the molecule is encoded by six shorter exons. In addition to the major cDNA species, a second class of MOG cDNA was isolated in which an intron was retained. Not only did this second cDNA species represent 30% of the clones analyzed (nine of 30), but RNA encoding this form was detectable by northern and reverse transcription-polymerase chain reaction analysis of the brain and spinal cord. Furthermore, we describe several restriction fragment length polymorphisms of the human MOG gene, one of which may be associated with MS susceptibility.

Myelin oligodendrocyte glycoprotein induces a demyelinating encephalomyelitis resembling multiple sclerosis

Chronic relapsing experimental autoimmune encephalomyelitis, a demyelinating disease induced by injection of central nervous system (CNS) tissue, is widely used as a model for multiple sclerosis. However, it is unclear which Ag or combination of Ags in the CNS induce the demyelinating immune response. We now show in Lewis rats that a single injection of myelin oligodendrocyte glycoprotein, a specific CNS myelin component, or an appropriately derived myelin oligodendrocyte glycoprotein peptide produces a relapsing remitting neurologic disease with extensive plaque-like demyelination. Igs from affected animals reacted specifically with myelin oligodendrocyte glycoprotein and stimulated a myelin protease activity, leading to myelin basic protein degradation. The demonstrated involvement of myelin oligodendrocyte glycoprotein as a new demyelinating neural Ag may provide a deeper insight into the pathogenesis of multiple sclerosis and its treatment.

Myelin oligodendrocyte glycoprotein induces a demyelinating encephalomyelitis resembling multiple sclerosis

Chronic relapsing experimental autoimmune encephalomyelitis, a demyelinating disease induced by injection of central nervous system (CNS) tissue, is widely used as a model for multiple sclerosis. However, it is unclear which Ag or combination of Ags in the CNS induce the demyelinating immune response. We now show in Lewis rats that a single injection of myelin oligodendrocyte glycoprotein, a specific CNS myelin component, or an appropriately derived myelin oligodendrocyte glycoprotein peptide produces a relapsing remitting neurologic disease with extensive plaque-like demyelination. Igs from affected animals reacted specifically with myelin oligodendrocyte glycoprotein and stimulated a myelin protease activity, leading to myelin basic protein degradation. The demonstrated involvement of myelin oligodendrocyte glycoprotein as a new demyelinating neural Ag may provide a deeper insight into the pathogenesis of multiple sclerosis and its treatment.

Purification of histamine receptor proteins from detergent-solubilized human peripheral blood mononuclear cells

Histamine is released from mast cells and basophils by either immunological or nonimmunological mechanisms. Histamine, which is the most potent short acting mediator released from these cells, exerts its diverse biological actions by binding to cell surface histamine receptors. We report the affinity purification of histamine receptor proteins from Triton X-100 solubilized peripheral human blood mononuclear cells which include lymphocytes and monocytes. Three different designs of histamine affinity columns were constructed; all three resulted in the same material being eluted. This consisted of bands which on SDS-PAGE after boiling and reduction had the following molecular weights: 193K, 84K, 58K, 48K, 37K, and 16K. The most abundant bands were of molecular weights 193K, 48K, and 16K, and these were disulfide bonded together to form a high molecular weight complex. (The 58K band was present in lower amounts than the others, and in only a few fractions. It had the same molecular weight as the dimeric form of histamine methyltransferase which is present in small amounts in mononuclear cells and may therefore have copurified.) The histamine binding proteins described in this report were purified by conventional affinity chromatography, rather than by an expression cloning approach which obviates the use of any protein chemistry. Consequently, we had the advantage of being able to verify the histamine binding specificity of our purified proteins directly and with several independent assays as follows. The histamine binding specificity of all three columns was established by specific elution with histamine, by preabsorption of crude cell extract with excess free histamine prior to column application, and by comparison with control columns. Independent determination of the binding specificity, using a radioreceptor dot blot assay, of the eluate containing only the 193K, 48K, and 16K disulfide-linked subunits confirmed that the purified material bound specifically to [3H]histamine and that a 300-500-fold degree of purification from tissue extract had been obtained. Following cell surface radioreceptor cross-linking of radiolabeled histamine to intact mononuclear cells, the 16K band was detected, indicating it to be the ligand-binding subunit for histamine. These same three proteins were purified from T lymphocyte and monocytoid cell lines, indicating that both lymphocyte and monocyte subsets of mononuclear cells express these proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Reactivity to myelin antigens in multiple sclerosis. Peripheral blood lymphocytes respond predominantly to myelin oligodendrocyte glycoprotein

Although T cell responses to the quantitatively major myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP), are likely to be of importance in the course of multiple sclerosis (MS), cell-mediated autoimmune responses to other myelin antigens, in particular quantitatively minor myelin antigens, such as myelin-associated glycoprotein (MAG) and the central nervous system-specific myelin oligodendrocyte glycoprotein (MOG), could also play a prevalent role in disease initiation or progression. Highly purified myelin antigens were used in this study to assess cell-mediated immune response to MOG in MS patients, in the context of the reactivity to other myelin antigens, MBP, PLP, and MAG. The greatest incidence of proliferative response by MS peripheral blood lymphocytes was to MOG, as 12 of 24 patients tested reacted and, of these, 8 reacted to MOG exclusively. In contrast, only 1 control individual of 16 tested reacted positively to MOG. The incidence of responses to MBP, PLP, and MAG did not differ greatly between MS patients and control individuals. A predominant T cell reactivity to MOG in MS suggests an important role for cell-mediated immune response to this antigen in the pathogenesis of MS.

Human myelin/oligodendrocyte glycoprotein: a new member of the L2/HNK-1 family

Myelin/oligodendrocyte glycoprotein (MOG) is a quantitatively minor component of CNS myelin. In this study, human MOG was found to express the L2/HNK-1 epitope on N-linked oligosaccharide structures. This carbohydrate epitope has been found previously in three other characterized human myelin glycoproteins: the myelin-associated glycoprotein, P0, and the oligodendrocyte-myelin glycoprotein. It seems, therefore, that the L2/HNK-1 epitope is expressed frequently in human myelin glycoproteins. Serial lectin affinity chromatography of 14C-glycopeptides indicated that MOG N-oligosaccharide structures are mainly of the complex type, accounting for 77.8% of total radioactivity. In contrast with myelin-associated glycoprotein and P0, which express the L2/HNK-1 epitope on fucosylated structures, in MOG the epitope was detected on all glycopeptide fractions obtained by serial lectin affinity chromatography, although a preferential expression of the L2/HNK-1 epitope was observed on fucosylated structures. Finally, the data indicated that, as for other human myelin glycoproteins, only a subpopulation of MOG molecules expresses the L2/HNK-1 epitope.

Identification of two human brain aryl sulfotransferase cDNAs

A 1,179 bp and a 1,424 bp full-length aryl sulfotransferase cDNAs were isolated from a human brain cDNA library. Their coding domains are 93% identical, each encoding a cytosolic protein of 295 amino acids. Their deduced amino acid sequences of these cDNAs are also 93% identical. The 1179 bp brain cDNA has an identical coding domain to a previously reported human liver aryl sulfotransferase cDNA but it has a different 5' noncoding sequence. Northern blot analysis using a probe specific for the 1,424 bp cDNA identified a 1500 bp band in mRNA of human liver, colon, kidney and lung. In a human hepatocellular carcinoma the same band plus an extra larger band was also recognised. An intron of the gene encoding the 1424 bp cDNA was also identified.

Preparation of highly purified human myelin oligodendrocyte glycoprotein in quantities sufficient for encephalitogenicity and immunogenicity studies

Myelin oligodendrocyte glycoprotein, (MOG), a quantitatively minor central nervous system (CNS) myelin component, is a candidate target antigen for autoimmune-mediated demyelination. It is a highly hydrophobic protein present in very small amounts in CNS tissue and thereby difficult to purify. Our aim was to devise a purification procedure that would yield sufficient quantities of highly purified MOG to subsequently test its potential encephalitogenic activity, as well as investigate the humoral and cell-mediated responses to this antigen in naturally occurring and experimentally induced autoimmune demyelinating diseases. MOG was purified from human CNS white matter using immunoaffinity chromatography, a procedure that gave a final yield of MOG corresponding to 0.02% total white matter protein. The final product, which migrated as two bands of molecular weight 28 kDa and 58 kDa, was highly pure as shown also by specific reactivity with monoclonal anti-MOG antibodies on immunoblots in the absence of any detectable reactivity with antibodies specific for myelin basic protein, proteolipid protein and myelin-associated glycoprotein. Partial amino acid sequence was obtained from both MOG bands separated by SDS-PAGE and electroblotted onto PVDF. The sequence of the first 17 N-terminal amino acids had approximately 55% homology with the reported rat MOG sequence deduced from the cloned cDNA sequence; small internal sequences obtained showed also very high homology. Our purified MOG preparations have been used to investigate T cell response to MOG by peripheral blood lymphocytes of multiple sclerosis patients and to induce a relapsing remitting demyelinating disease in Lewis rats.

Gamma delta T cell receptor repertoire in brain lesions of patients with multiple sclerosis

The identification of activated T cells in the brains of patients with multiple sclerosis (MS) suggests that these cells are critical in the pathogenesis of this disease. Recently we have used the PCR method to analyse rearrangements of V alpha and V beta genes of the T cell receptor (TCR) in samples of MS and control brains. The results of these studies showed that TCR V gene usage in MS brains may be restricted and in particular that V beta genes may be preferentially rearranged in certain HLA haplotypes associated with susceptibility to MS. In view of the recent evidence that T lymphocytes bearing the gamma delta chains may have autoreactive potential, we have assessed whether or not such TCR-bearing lymphocytes were also present in chronic MS lesions. TCR V gamma and V delta were analysed by the PCR method using a panel of V gamma and V delta primers paired with C gamma or C delta primers in 12 MS brains, as well as in brain samples of ten normal post-mortem cases and three neurological controls. TCR V gamma-C gamma and V delta-C delta rearrangements were confirmed using Southern blotting and hybridisation of the PCR products with specific C gamma and C delta probes. Only one to four rearranged TCR V gamma and V delta transcripts were detected in each of the 23 brain samples obtained from 12 MS patients, with the majority of gamma delta T cells expressing the V gamma 2 and V delta 2 chains. In marked contrast, V gamma and V delta transcripts could only be found in one of the ten non-neurological control brains analysed. To assess the clonality of V gamma 2 and V delta 2 T cell receptor chains in the brain samples of MS patients, we have sequenced the junctional regions of the TCR V gamma-N-J gamma-C gamma and V delta-N-D delta-N-J delta-C delta segments amplified from brain tissues, CSF and spleens of two MS patients and from the spleen of two control subjects. The sequence analysis obtained so far shows no compelling evidence of an MS specific expansion of one or more clones expressing particular types of gamma delta T cell receptors. In contrast, a clonal expansion of a different population of TCR gamma delta-bearing T cells was found in the spleen of both an MS patient and one of the control individuals.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular detection of interferon-alpha expression in multiple sclerosis brain

The demonstration of intermittent interferonaemia in patients with multiple sclerosis prompted a molecular analysis of brain tissue for expression of interferon-alpha genes. A sensitive method was developed based on the polymerase chain reaction. Primer sets were used that could amplify all interferons-alpha or two particular subtypes, interferon-alpha 2 and interferon-alpha 4. The procedure was successful in detecting expression of interferons-alpha in brain and non-brain tissues in most patients with multiple sclerosis. However, expression was demonstrable also in a similar proportion of patients with other neural diseases, and patients with other illnesses. The data indicate that there can be constitutive expression of interferons-alpha in brain tissue, but the possibility that this becomes amplified in multiple sclerosis was not revealed by this study.

Selection for T-cell receptor V beta-D beta-J beta gene rearrangements with specificity for a myelin basic protein peptide in brain lesions of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system in which a restricted cellular immune response has been observed. In order to establish whether such T cell responses are likely to be antigen-specific particularly with regard to myelin basic protein (MBP), we analysed T-cell receptor (TCR) gene rearrangements directly from MS brain plaques, using the polymerase chain reaction on reverse transcribed messenger RNA, and compared these with TCR of previously described MBP-specific T cell clones from MS and the rat model experimental allergic encephalomyelitis. Rearranged V beta 5.2 genes were detected in the brains of all patients who were HLA DRB1*1501, DQA1*0102, DQB1*0602, DPB1*0401. The V beta 5.2-D beta-J beta sequences in these MS brain plaques revealed five motifs. One of the common motifs was identical to that described for the VDJ region of a V beta 5.2 T-cell clone. This clone was from an MS patient who was HLA DRB1*1501, DQB1*0602, DPB1*0401, and it was cytotoxic towards targets containing the MBP peptide 89-106 (ref. 1). The deduced amino-acid sequence of this VDJ rearrangement, Leu-Arg-Gly, has also been described in rat T cells cloned from experimental allergic encephalomyelitis lesions, which are specific for MBP peptide 87-99 (ref. 2). VDJ sequences with specificity for this MBP epitope constitute a large fraction (40%) of the TCR V beta 5.2 N(D)N rearrangements in MS lesions. The capacity of rat T cells with these VDJ sequences to cause experimental allergic encephalomyelitis and the prevalence of such sequences in demyelinated human lesions indicate that T cells with this rearranged TCR may be critical in MS.

Purified antichick Thy-1 IgG abolishes intermediate and long-term memory

One- to 2-day-old chicks administered purified antichick Thy-1 IgG showed substantial amnesia for a single-trial passive discriminated avoidance task. Amnesia was clearly evident at 30 min after learning, during the intermediate stage of a three-stage model of memory processing, and persisted for at least 3 h. A similar effect was also observed with Fab and F(ab')2 fragments. Fc fragments, the non-IgG fraction of ascites, and saline yielded normal retention levels at all times. These results contrast with our earlier reports that both polyclonal and monoclonal antibodies to chick Thy-1 inhibited long-term memory formation only. The present findings are interpreted as possibly representing a dual effect of the purified IgG.

Multiple sclerosis: an autoimmune disease of multifactorial etiology

The etiology of multiple sclerosis is linked to a variety of genetic and environmental factors. Both cell-mediated and humoral immune responses, triggered by extraneous or autoantigens, are likely to contribute to the pathogenesis of this disease. A greater insight into the fundamental cause of multiple sclerosis has been provided by the recognition that certain immune response genes are associated with an increased susceptibility to the disease. Such knowledge should provide new opportunities for selective therapeutic interventions.

Differing epitope selection of experimentally-induced and natural antibodies to a disease-specific autoantigen, the E2 subunit of pyruvate dehydrogenase complex (PDC-E2)

Naturally-occurring autoantibodies to a family of mitochondrial enzymes, the 2-oxoacid dehydrogenase complexes (2-OADC), characterize the human liver disease primary biliary cirrhosis. The immunodominant epitope for these autoantibodies is associated with the lipoyl-binding domain of the E2 subunit of the enzymes. The reactivity of these disease-associated autoantibodies was compared with that of antibodies raised in rats and rabbits, by immunization with various preparations derived from the 2-OADC enzymes, using immunization protocols that have successfully induced various organ-specific autoimmune diseases in animals. The immunogens included the intact pyruvate dehydrogenase complex (PDC) from bovine heart, human recombinant PDC-E2, and short synthetic peptides representing the immunodominant lipoic acid binding sequences of the 2-OADC enzymes. The techniques for antibody analysis included immunofluorescence, immunoblotting on mitochondrial extracts, ELISAs using entire PDC, PDC-E2, or synthetic peptides, epitope mapping by peptide scanning on overlapping octameric peptides representing the human PDC-E2 sequence, affinity purification on PDC-E2, and inhibition in vitro by sera of the catalytic function of PDC. Experimental immunization did not elicit any evidence of autoimmune disease. Moreover, the experimentally-induced antibodies in striking contrast to the natural autoantibodies showed preferential reactivity with PDC-E2 rather than with intact PDC, failed to inhibit in vitro the catalytic function of PDC, and, on peptide scanning, reacted with discrete epitopes, but at sites other than the lipoyl-binding region of PDC-E2. Our data indicate that 'multisystem' autoimmune diseases including primary biliary cirrhosis may not be elicitable experimentally because a critical disease-relevant autoepitope is not engaged by the immune system.