Indicators of disease activity in multiple sclerosis. Studies of myelin basic protein-like materials

Prolonged exposure to one percent carbon monoxide causes a leucoencephalopathy in un-anaesthetised sheep

A total of 15 Levine-prepared adult un-anaesthetised sheep were exposed to 1% carbon monoxide (CO) in air for between 45 and 150 min. This exposure caused a reversible increase in blood carboxyhaemoglobin concentration and heart rate, and a similarly reversible decrease in electroencephalographic frequency and level of consciousness. sheep were either normotensive or slightly hypertensive. Sheep brains were subsequently examined for histopathological changes at either 5 or 14 days post- exposure. No dead neurons or apoptotic cells were seen, but most sheep given a prolonged exposure to CO had some axonal damage and associated gliosis. This damage was concentrated about necrotic micro-foci in the peri-ventricular white matter. These results suggest that a leucoencephalopathy is a primary consequence of acute and sub-acute CO toxicity.

Myelin basic protein-like material in the urine of multiple sclerosis patients: relationships to clinical and neuroimaging changes

Urinary myelin basic protein-like material (MBPLM) represents material which is cross-reactive with a cryptic epitope in peptide 84-89 of human myelin basic protein. While normally present at moderate levels in the adult, these levels rise higher in patients who have secondary progressive multiple sclerosis (MS). The increase in urine MBPLM correlates with the burden of disease detected by T2-weighted cranial magnetic resonance imaging. There is no correlation between urinary MBPLM and acute disease activity in relapsing-remitting MS. The first major need for improving the clinical utility of measurements of MBPLM in urine in MS patients is to delineate its exact chemical features so that assays may be improved and a potential biological role of the MBPLM better understood. The second major task is to apply the group data accumulated and apply them to individual patients. This could prove to be means to individually direct treatment and determine its effectiveness.

Free light chains in multiple sclerosis urine

We measured free kappa (kappa) and lambda (lambda) light chains in urine from patients with definite multiple sclerosis (MS), other neurologic diseases (OND), and normal controls by using an enzyme linked immunosorbent assay. Both kappa and lambda light chains were higher in MS than OND or controls. In seven of eight relapsing-remitting (R-R) MS patients serial studies showed that urinary kappa chains were elevated during periods of worsening, and decreased during clinical recovery. In contrast, the levels of kappa chains did not correlate with clinical activity in 10 progressive (P) MS patients. Further correlation of urinary light chains with neurologic evaluations in R-R and P MS patients over a longer period are needed to determine their clinical and biological relevance.

The effects of high-dose methylprednisolone on gadolinium-enhanced magnetic resonance imaging and cerebrospinal fluid measurements in multiple sclerosis

Blood-brain barrier (BBB) disruption is probably the first event in the lesion development in multiple sclerosis (MS). This stage can be visualized by gadolinium-enhanced magnetic resonance (MR) imaging of the brain. Serial MR imaging studies have indicated a continuous spectrum of disease activity with waxing and waning of acute lesions, even in clinically stable MS patients. High-dose intravenous methylprednisolone (MP) has a beneficial clinical effect; reduces gadolinium enhancement, indicating improvement of BBB integrity; and, in MS patients, decreases intrathecal immunoglobulin synthesis with reduction of cerebrospinal fluid (CSF) myelin basic protein (MBP). A correlative triad is noted between gadolinium enhancement, clinical improvement, and decrease of CSF MBP following MP treatment, indicating a relationship between restoration of BBB integrity, clinical improvement and decrease of myelin breakdown. It is not clear whether MP interferes primarily with the process of demyelination or reacts non-specifically with its mediators.

CSF myelin basic protein, IgG and IgM levels in 101 MS patients before and after treatment with high-dose intravenous methylprednisolone

A total of 101 patients (62 women; 39 men) with definite MS were treated with 1000 mg methylprednisolone (MP) intravenously for 10 consecutive days. Immediately before and after MP treatment clinical scoring (Kurtzke's Expanded Disability Status Scale) and CSF analysis were performed. Before MP treatment CSF MBP, IgG and IgM immunoglobulin levels (CSF Ig, index and intrathecal synthesis) were significantly elevated. The mean CSF MBP levels were significantly higher in the relapsing-remitting (RR) and chronic progressive MS patients with relapses (CP + RR) than in the CP group without a RR disease course, respectively 2.1, 2.3 and 1.5 micrograms/l. A weak positive correlation was found between CSF MBP level and EDSS in the RR MS group (r = 0.34). CSF MBP was significantly correlated with IgM index (r = 0.36), IgM synthesis (r = 0.26), but not with the IgG levels. Therefore demyelination seems to be related to intrathecal IgM production. After MP treatment mean (median) EDSS decreased from 4.4 (4.0) to 3.3 (3.0). Except for Q albumin and IgM index, all CSF immunoglobulin levels decreased significantly after MP. The mean CSF MBP returned to reference values. In the RR group the decrease in CSF MBP was significantly correlated with the change in EDSS (r = 0.39). CSF MBP seems to be a good parameter for disease activity in relapsing MS. Following treatment CSF MBP was found to be related with the change in IgM index (r = 0.30). MP treatment reduces CSF MBP and intrathecal IgM in a similar way indicating a relation between these 2 parameters.

An enzyme-linked immunosorbent assay for myelin basic protein-specific protein methylase I

A sandwich enzyme-linked immunosorbent assay (ELISA) has been developed to determine myelin basic protein (MBP)-specific protein methylase I. Rabbit immunoglobulin anti-bovine MBP-specific protein methylase I, purified by Sepharose-A affinity chromatography, was utilized as the primary antibodies, while the same antibodies which had been conjugated to peroxidase were employed as the indicator antibodies. This assay method was about 280 times more sensitive than the conventional trichloracetic acid (TCA) precipitation method. Employing the ELISA, the level of MBP-specific protein methylase I during mouse brain development was examined; the peak level of the methylase was shown to be at 16th postnatal day, indicating temporal correlation with myelination. Among several species of brains examined, human showed the highest and carp the least amount of MBP-specific protein methylase I; 6.33 micrograms and 0.33 micrograms per mg of brain cytosol protein, respectively. Dysmyelinating jimpy hemizygous mouse brain showed the immunoreactive MBP-specific protein methylase only 60% that of the control at 20 days of age. The high sensitivity of the method together with the fact that MBP-specific protein methylase is present in human cerebrospinal fluid suggests a possible clinical application of this method for evaluating demyelinating disorders.

Glycosphingolipids in the cerebrospinal fluid of patients with multiple sclerosis

Glycosphingolipids in cerebrospinal fluid (CSF) of individual patients with multiple sclerosis (MS) were analyzed using a glycolipid-overlay technique. The ganglioside composition of CSF of non-MS patients was characterized by an abundance of polysialo species, including GT1b and GQ1b. This pattern is completely different from that of human white or gray matter, in which mono- and disialogangliosides predominate. Increased levels of GM1, either associated with or without increases of other gangliosides, such as GD1a, were observed in 16% of the patients with MS (6 of 37 cases: 1 of 15 progressive progressive stage, 4 of 16 progressive stationary stage, and 1 of 6 relapsing stage). The concentration of GD3 was increased in 23% (3 of 13 cases), whereas 1 of 13 cases (8%) showed a dramatic increase of sulfoglucuronyl paragloboside (SGPG) associated with a high level of GD3. These changes may reflect the cellular changes associated with the known pathological lesions in MS, which are characterized by demyelination, gliosis, and/or remyelination with oligodendrocytic proliferation.

Detection of myelin basic protein-like material in cerebrospinal fluid of multiple sclerosis patients by immunoblot assay

Myelin basic protein (MBP)-like material in 15 cerebrospinal fluid (CSF) samples from patients with multiple sclerosis (MS) was analyzed by isoelectric focusing (IEF) followed by immunoblot assay using rabbit antiserum against human MBP- peptide 69-89, which contains the dominant epitope for MBP-like material. Samples from seven of 10 MS patients with disease in the exacerbation stage showed one band and in three other samples, a number of faint bands also appeared in the alkaline pH region in addition to the one band. CSF from five MS patients whose disease was in remission showed no detectable bands. Our results are consistent with those obtained by quantitative assay, reported in the literature.

Studies on protein methyltransferase in human cerebrospinal fluid

Protein methyltransferases, rich in most mammalian brains, were studied in human cerebrospinal fluid (CSF). Among several well-characterized groups of methyltransferases, protein methylase I (S-adenosylmethionine:protein-arginine N-methyltransferase, EC 2.1.1.23) was found in significant amounts in human CSF samples. Both myelin basic protein (MBP) -specific and histone-specific protein methylase I activities were observed, the latter being generally higher in most CSF. S-Adenosyl-L-homocysteine, a potent product inhibitor for the methyltransferase, inhibited approximately 90% of MBP-specific protein methylase I activity at a concentration of 1 mM. The optimum pH of the MBP-specific protein methylase I was found to be around 7.2. Identity of exogenously added MBP as the methylated substrate for CSF enzyme was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. An amino acid analysis of the [methyl-3H]protein hydrolysate showed two major radioactive peaks cochromatographing with monomethyl- and dimethyl (symmetric)-arginine. Human CSF contained relatively high endogenous protein methylase I activity (activity measured without added substrate protein): The endogenous substrate can be immunoprecipitated by antibody raised against calf brain MBP. Finally, CSF from several neurological patients were analyzed for protein methylase I, and the results are presented.

Peptides of myelin basic protein stimulate T lymphocytes from patients with multiple sclerosis

Peripheral blood T lymphocytes from patients with multiple sclerosis (MS) and other neurological diseases (OND) were tested for primary in vitro proliferation in response to four synthetic peptides derived from the sequence of human myelin basic protein (HuMBP) and to HuMBP 45-89 peptide fragment, using a [3H]thymidine incorporation assay. The synthetic peptides used corresponded to residues HuMBP 15-31, 75-96, 83-96 and 131-141 of human myelin basic protein. Significant proliferation of T lymphocytes to peptides was noted only in the MS group (with the exception of peptide 131-141): the majority of control subjects and OND patients did not respond to the above-mentioned peptides. The sensitized T lymphocytes in MS patients displayed the inducer/helper phenotype and required autologous monocytes for optimal proliferation. An anti-HLA-DR monoclonal antibody, directed against a monomorphic determinant of DR molecules, was able to block the responses in a dose-dependent fashion. These results suggest that autoimmune inducer/helper T lymphocytes in the peripheral blood of MS patients may initiate and/or regulate the demyelination process in patients with MS. Furthermore, our data demonstrate that monocytes and HLA-DR molecules are essential for activation of these cells. Finally primary in vitro T cell proliferation to HuMBP synthetic peptide may be used as an additional diagnostic test in MS.

Myelin basic protein and magnetic resonance imaging for diagnosing radiation myelopathy

The identification of radiation myelopathy using biochemical assays and imaging techniques has not previously been accomplished but has clear clinical application. Measurement of myelin basic protein (MBP) in the cerebrospinal fluid (CSF) and visualization of the spinal cord using magnetic resonance imaging (MRI) gives a potentially accurate diagnosis of radiation myelopathy. Female New Zealand white rabbits were irradiated to the thoracic spinal cord with single doses of 15-45 Gy. Animals receiving higher doses (greater than or equal to 22 Gy) generally demonstrated an early paresis (4-8 weeks) that temporarily improved, and then progressed to complete paralysis by 14-18 weeks. MBP levels in the CSF became strikingly elevated to 100-1000 times the normal value. Subsequent, experiments in which rabbits were serially assessed for MBP levels demonstrated a transient elevation, which corresponded to the transient paresis, followed by dramatic elevations concurrent with the onset of paralysis. Magnetic resonance imaging (MRI) of the irradiated spinal cord showed a geographically distinct region of abnormality that corresponded to the radiation field. Histopathology demonstrated demyelination, focal astrocytosis, erythrodiapedesis, and perineuronal edema in the irradiated sections. It appears that MBP levels in the CSF reflect not only radiation-induced myelopathy but also transient demyelination, and that MRI may have the potential to indicate the region of damage.

New monoclonal antibodies reactive with defined sequential epitopes in human myelin basic protein

Three new IgG monoclonal antibodies are described which recognise sequential epitopes of the human myelin basic protein (MBP) molecule in amino acid sequences 36-50, 64-75 and 80-89. Two of the secreting hybridomas were prepared by immunisation of mice with synthetic peptides. This procedure appears to generate antibodies of similar affinities to those made using intact myelin basic protein as the immunogen. It has the advantage that antibodies to preselected regions of the molecule can be made at will and the problem of subsequent epitope localisation is simplified. It is possible with synthetic peptides to generate antibodies of specificities which it would be impossible to achieve by immunisation with intact myelin basic protein. The monoclonal antibodies described here should be useful tools in studies of myelin catabolism in vivo and in vitro. Of particular interest is our Clone 22, making an antibody which reacts equally well with intact human MBP and synthetic peptide sequence 80-89 in liquid phase assays. Antibodies of this rare specificity have been claimed to be able to react with the peptides of myelin basic protein found in the spinal fluid of patients with multiple sclerosis.

Human myelin basic protein peptide 69-89: immunochemical features and use in immunoassays of cerebrospinal fluid

The characteristics and heterogeneity of the myelin basic protein (MBP)-like material appearing in cerebrospinal fluid (CSF) after acute central nervous system (CNS) myelin injury are unresolved. Antigenic material containing an epitope in the carboxyl-terminal portion of human MBP peptide 45-89 (from the intact molecule of 170 residues) is a prominent species of the MBP-like material present. In an effort to define further the MBP-like material in CSF and to enhance its detection, a modified double-antibody radioimmunoassay has been developed using a radioligand of human MBP synthetic peptide 69-89. This assay is more sensitive with results paralleling those of previously used MBP assays for CNS myelin damage. Results with this assay provide additional confirmation of the presence of an epitope of MBP in the decapeptide of MBP 80-89 but in a conformation simulating that of intact MBP in CSF after CNS myelin injury. Unexpected buffer effects were noted to influence the immunochemical behavior of some of the small peptides of MBP.

A new epitope on human myelin basic protein arising from cleavage by a metalloendoprotease associated with brain myelin membranes

Human brain myelin membranes were incubated to allow activity of an associated metalloendoprotease which cleaves myelin basic protein (MBP). A 10.3 kDa C-terminal fragment of MBP, peptide C, isolated from the incubation medium had a blocked N-terminal. After treatment with pyroglutamyl aminopeptidase, N-terminal sequencing indicated that Gln74 of MBP formed the N-terminal residue of peptide C. A rabbit antiserum was raised to a synthetic peptide containing the sequence Pyroglu-Lys-Ser-His-Gly-Arg, corresponding to the first six residues of peptide C. By immunoblotting this serum reacted with peptide C but not with intact MBP. The data indicate that cleavage of MBP by a myelin-associated protease engenders a new epitope.

The imbalance in CSF T cell subsets in active multiple sclerosis

We determined the percentage of each lymphocyte subpopulation in the cerebrospinal fluid (CSF) and the peripheral blood of 7 patients with active multiple sclerosis (MS), 7 with inactive MS, 5 with other inflammatory diseases in the central nervous system, and 12 with non-inflammatory neurological diseases, using fluorescein-labelled monoclonal antibodies (anti-Leu7, anti-HLA-DR, and those that recognize such surface antigens as CD3, CD4, CD8, and CD19), and by laser flow cytometry to clarify the clinical usefulness of their measurement in the assessment of disease activity in MS. In CSF, a significant increase in the percentage of CD4+ cells and a significant decrease in the percentage of CD8+ cells were observed in the active MS group compared with the other 3 groups, while none of the percentages of the 6 subsets studied in the peripheral blood were significantly different among these groups. Our preliminary study indicated that evaluation of the percentages of CD4+ and CD8+ cells in CSF by flow cytometry could be a useful indicator of disease activity in MS.

Measurement of immunoreactive myelin basic protein peptide (45-89) in cerebrospinal fluid

To measure myelin basic protein (MBP)-like material in cerebrospinal fluid, we compared two radioimmunoassays, both using the same antiserum to MBP but one using peptide (45-89) as the radioligand and standard (peptide assay), and the other using purified MBP as the radioligand and standard (MBP assay), with respect to their diagnostic sensitivity. Cerebrospinal fluid specimens from 185 patients with definite multiple sclerosis (MS) (n = 27), possible MS (n = 63), probable MS (n = 24), and other neurological disease (n = 71) were analyzed using both assays. The diagnostic sensitivity of the peptide assay was significantly better than that of the MBP assay in those with definite MS (sensitivity 59% and 30%, respectively); there was no significant difference in specificity. The peptide assay also showed better correlation with disease activity than the MBP assay: 14 patients classified as having active MS showed significantly higher sensitivity (78.6% versus 38%, p less than 0.04) when compared to patients with inactive disease. The MBP assay showed no significant difference between these two groups. Besides the increase in sensitivity, the actual molar concentrations of immunoreactive MBP detected using this peptide assay were considerably higher than those found using the MBP assay. These results show that the use of MBP antisera capable of recognizing epitopes present in the carboxyl half of MBP peptide (45-89) results in more sensitive detection of immunoreactive MBP when used with MBP peptide (45-89) as radiolabeled ligand in the assay.

Epitopes of immunoreactive myelin basic protein in human cerebrospinal fluid

To define in more detail the features of the immunoreactive myelin basic protein (MBP) present in cerebrospinal fluid (CSF) of humans following acute injury to central nervous system myelin, the epitopes of MBP recognized by three different antisera, each capable of detecting immunoreactive MBP in CSF, were examined. All three antisera reacted well with human MBP and human MBP peptide 45-89. Only in radioimmunoassays in which the MBP peptide 45-89 served as the radioligand could clearly elevated values of immunoreactive MBP be measured in CSF specimens from 5 patients with multiple sclerosis during or immediately after an exacerbation. The two antisera that reacted well with MBP peptide 80-89 resulted in higher levels of immunoreactive MBP measured in CSF. An epitope present in human MBP peptide 80-89 but sharing a conformation with both MBP and MBP peptide 45-89 is present in CSF following acute central nervous system myelin damage in multiple sclerosis.

Analysis of the primary sequence of human myelin basic protein peptides 1-44 and 90-170 by fast atom bombardment mass spectrometry

The originally described sequence of human myelin basic protein peptide 45-89 has recently been shown to contain two errors which have now been resolved. In the present study fast atom bombardment mass spectrometry was utilized to analyze the primary sequence of the other portions, peptides 1-44 and 90-170 of human myelin basic protein. The results obtained confirm the accuracy of the primary sequence published for both of these terminal peptides.

Multiple sclerosis: neuroimmunologic puzzle

Multiple sclerosis (MS), a chronic disease with a relapsing and remitting course, is the most common neuroimmunologic condition in the United States. The hallmarks of the disease are focal demyelination and inflammation within the central nervous system (CNS). Because histopathologic changes can be identified only at autopsy, attention has been directed at formulating standardized clinical and laboratory procedures to aid in MS diagnosis. Currently, there are no MS-specific clinical or laboratory tests, but detection of abnormality in cerebrospinal fluid (CSF) IgG is important in supporting clinical evidence of disease. A number of other immunologic abnormalities have been recognized in MS, including the presence of T- and B-lymphocytes within the CNS and alterations in circulating suppressor T-lymphocytes. These findings have been interpreted as indicating disturbed immunoregulation associated with a chronic autoimmune response within the CNS. Evidence implicates viral infection in the pathogenesis of MS but the cause of the disease remains unknown.