Essential fatty acids in the serum and cerebrospinal fluid of multiple sclerosis patients

A Systematic Review on the Role of Arachidonic Acid Pathway in Multiple Sclerosis

BACKGROUND & OBJECTIVE

Multiple sclerosis (MS) is an inflammatory neurodegenerative disease characterized by destruction of oligodendrocytes, immune cell infiltration and demyelination. Inflammation plays a significant role in MS, and the inflammatory mediators such as eicosanoids, leukotrienes, superoxide radicals are involved in pro-inflammatory responses in MS. In this systematic review we tried to define and discuss all the findings of in vivo animal studies and human clinical trials on the potential association between arachidonic acid (AA) pathway and multiple sclerosis.

METHODS

A systematic literature search across Pubmed, Scopus, Embase and Cochrane database was conducted. This systematic review was performed according to PRISMA guidelines.

RESULTS

A total of 146 studies were included, of which 34 were conducted in animals, 58 in humans, and 60 studies reported the role of different compounds that target AA mediators or their corresponding enzymes/ receptors, and can have a therapeutic effect in MS. These results suggest that eicosanoids have significant roles in experimental autoimmune encephalomyelitis (EAE) and MS. The data from animal and human studies elucidated that PGI2, PGF2α, PGD2, isoprostanes, PGE2, PLA2, LTs are increased in MS. PLA2 inhibition modulates the progression of the disease. PGE1 analogues can be a useful option in the treatment of MS.

CONCLUSIONS

All studies reported the beneficial effects of COX and LOX inhibitors in MS. The hybrid compounds, such as COX-2 inhibitors/TP antagonists and 5-LOX inhibitors can be an innovative approach for multiple sclerosis treatment. Future work in MS should shed light in synthesizing new compounds targeting arachidonic acid pathway.

An overview of lipidomic analysis in different human matrices of multiple sclerosis

Multiple sclerosis is a chronic inflammatory and neurodegenerative disease of the central nervous system, and it is one of the most common neurological cause of disability in young adults. It is known that several factors contribute to increase the risk of development and pathogenesis of multiple sclerosis, nonetheless, but the true etiology of this pathology remains unknown. Similar to other inflammatory diseases, oxidative stress and lipid peroxidation are also associated to multiple sclerosis. Alterations in the lipid profile seem to be a hallmark of this pathology which can contribute to the dysregulation of lipid homeostasis and lipid metabolism in multiple sclerosis. Lipidomic studies analysed in this review clearly demonstrate the role of lipids in inflammatory processes, in immunity, and in the onset and development of multiple sclerosis. Several investigations reported alterations of some molecular lipid species, in particular, with decrease of fatty acids (FA) 18:2 and 20:4 and total polyunsaturated FA, with compensatory increases of saturated FA with shorter carbon chains. Oxidized phospholipids were reported in few studies as well. Also, it was shown that clinical lipidomics has potential as a tool to aid both in multiple sclerosis diagnosis and therapeutics by allowing a detailed lipidome profiling of the patients suffering with this disease.

Moving past antioxidant supplementation for the dietary treatment of multiple sclerosis

Current research has demonstrated the definitive presence of oxidative stress in multiple sclerosis (MS). This finding has led to clinical trial research which has indicated that specific antioxidants have the ability to effectively reduce markers of oxidative stress. However, few interventions testing antioxidant supplements have shown efficacy for reducing the symptom burden in the disorder. This paper quickly reviews what is currently known about oxidative stress and antioxidants in MS, explains which nutrients are critical for the creation and maintenance of the myelin sheath, describes potential negative effectors in the diet which may be contributing to oxidative stress, and how these aspects of diet, combined with current knowledge on antioxidants, may be able to be combined into a whole food dietary intervention which can be tested for efficacy in MS.

Multiple sclerosis

Multiple sclerosis (MS) is a chronic progressive demyelinating disease of the central nervous system. Common manifestations include paresthesias, diplopia, loss of vision, numbness or weakness of the limbs, bowel or bladder dysfunction, spasticity, ataxia, fatigue, and mental changes. Four main patterns of MS are recognized: relapsing remitting, primary progressive, secondary progressive, and progressive relapsing. The cause of MS is unknown, although it appears to be an autoimmune disease. Much of what is known about MS has been learned from an animal model of the disease, experimental allergic encephalomyelitis.

Nutritional factors and aging in demyelinating diseases

Demyelination is a pathological process characterized by the loss of myelin around axons. In the central nervous system, oligodendroglial damage and demyelination are common pathological features characterizing white matter and neurodegenerative disorders. Remyelination is a regenerative process by which myelin sheaths are restored to demyelinated axons, resolving functional deficits. This process is often deficient in demyelinating diseases such as multiple sclerosis (MS), and the reasons for the failure of repair mechanisms remain unclear. The characterization of these mechanisms and the factors involved in the proliferation, recruitment, and differentiation of oligodendroglial progenitor cells is key in designing strategies to improve remyelination in demyelinating disorders. First, a very dynamic combination of different molecules such as growth factors, cytokines, chemokines, and different signaling pathways is tightly regulated during the remyelination process. Second, factors unrelated to this pathology, i.e., age and genetic background, may impact disease progression either positively or negatively, and in particular, age-related remyelination failure has been proven to involve oligodendroglial cells aging and their intrinsic capacities among other factors. Third, nutrients may either help or hinder disease progression. Experimental evidence supports the anti-inflammatory role of omega-6 and omega-3 polyunsaturated fatty acids through the competitive inhibition of arachidonic acid, whose metabolites participate in inflammation, and the reduction in T cell proliferation. In turn, vitamin D intake and synthesis have been associated with lower MS incidence levels, while vitamin D-gene interactions might be involved in the pathogenesis of MS. Finally, dietary polyphenols have been reported to mitigate demyelination by modulating the immune response.

Lipids and lipid-reactive antibodies as biomarkers for multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that targets the central nervous system (CNS). MS initially follows a relapsing-remitting course (RRMS) in which acute attacks are followed by a complete recovery. Eventually, 65% of the RRMS patients go on to develop secondary progressive MS (SPMS), characterized by the progressive and irreversible accumulation of neurological disability. It has been proposed that the transition from RRMS to SPMS results from changes in the nature of the inflammatory response and the progressive accumulation of neurodegeneration. To date, however, there is no reliable method to monitor the activity of the different immune and neurodegenerative processes that contribute to MS pathology. Thus, there is a need for biomarkers useful for the diagnosis, treatment and monitoring of MS patients. In this review, we discuss the potential use of lipids and the immune response against them as biomarkers of inflammation and neurodegeneration for MS.

Metabolomic analysis of the cerebrospinal fluid reveals changes in phospholipase expression in the CNS of SIV-infected macaques

HIV infiltrates the CNS soon after an individual has become infected with the virus, and can cause dementia and encephalitis in late-stage disease. Here, a global metabolomics approach was used to find and identify metabolites differentially regulated in the cerebrospinal fluid (CSF) of rhesus macaques with SIV-induced CNS disease, as we hypothesized that this might provide biomarkers of virus-induced CNS damage. The screening platform used a non-targeted, mass-based metabolomics approach beginning with capillary reverse phase chromatography and electrospray ionization with accurate mass determination, followed by novel, nonlinear data alignment and online database screening to identify metabolites. CSF was compared before and after viral infection. Significant changes in the metabolome specific to SIV-induced encephalitis were observed. Metabolites that were increased during infection-induced encephalitis included carnitine, acyl-carnitines, fatty acids, and phospholipid molecules. The elevation in free fatty acids and lysophospholipids correlated with increased expression of specific phospholipases in the brains of animals with encephalitis. One of these, a phospholipase A2 isoenzyme, is capable of releasing a number of the fatty acids identified. It was expressed in different areas of the brain in conjunction with glial activation, rather than linked to regions of SIV infection and inflammation, indicating widespread alterations in infected brains. The identification of specific metabolites as well as mechanisms of their increase illustrates the potential of mass-based metabolomics to address problems in CNS biochemistry and neurovirology, as well as neurodegenerative diseases.

Polyunsaturated fatty acids in the pathogenesis and treatment of multiple sclerosis

Epidemiological, biochemical, animal model and clinical trial data described in this overview strongly suggest that polyunsaturated fatty acids, particularly n-6 fatty acids, have a role in the pathogenesis and treatment of multiple sclerosis (MS). Data presented provides further evidence for a disturbance in n-6 fatty acid metabolism in MS. Disturbance of n-6 fatty acid metabolism and dysregulation of cytokines are shown to be linked and a "proof of concept clinical trial" further supports such a hypothesis. In a randomised double-blind, placebo controlled trial of a high dose and low dose selected GLA (18:3n-6)-rich oil and placebo control, the high dose had a marked clinical effect in relapsing-remitting MS, significantly decreasing the relapse rate and the progression of disease. Laboratory findings paralleled clinical changes in the placebo group in that production of mononuclear cell pro-inflammatory cytokines (TNF-alpha, IL-1beta) was increased and anti-inflammatory TGF-beta markedly decreased with loss of membrane n-6 fatty acids linoleic (18:2n-6) and arachidonic acids (20:4n-6). In contrast there were no such changes in the high dose group. The improvement in disability (Expanded Disability Status Scale) in the high dose suggests there maybe a beneficial effect on neuronal lipids and neural function in MS. Thus disturbed n-6 fatty acid metabolism in MS gives rise to loss of membrane long chain n-6 fatty acids and loss of the anti-inflammatory regulatory cytokine TGF-beta, particularly during the relapse phase, as well as loss of these important neural fatty acids for CNS structure and function and consequent long term neurological deficit in MS.

Multiple sclerosis and nutrition

Benefits from any particular diet in multiple sclerosis (MS) have not yet been proven. It is, however, frequent that malnutrition may potentially exacerbate the symptoms of MS. There is some evidence that a high intake of saturated fat increases the incidence of MS. Epidemiological studies imply that unsaturated fatty acids may have a positive effect on the course of MS. However, the results of controlled studies are ambiguous. A meta-analysis of three small controlled clinical trials suggests a benefit from linoleic acid. Intake of Vitamin D is associated with a lower incidence of MS. In MS, the risk of osteoporosis is high, and prophylactic vitamin D and calcium should be considered at an early stage. The role of minerals, trace elements, antioxidants, vitamins or fish oil is unclear. The possible relationships between diet and MS have not been subjected to adequate study. It seems possible that in the future, diets or dietary supplements may become recommended forms of treatment for MS.

[Diet and multiple sclerosis]

Beneficial effects from any particular diet have not been proven in multiple sclerosis (MS). Therefore, the general guidelines on nutrition should be followed. Obesity and various forms of malnutrition worsening the MS symptoms are frequently observed. There is some evidence from epidemiological studies that a high consumption of saturated animal fat is associated with an increased incidence of MS. The findings from such studies indicate that supplementation with unsaturated fatty acids, in particular omega-3 fatty acids, could positively influence the course of MS. However, controlled studies did not show clear beneficial effects from polyunsaturated fatty acids. The intake of vitamin D is associated with a lower incidence of MS. In contrast, the effects of therapy with vitamin D on the course of MS have not been ascertained. Patients with MS carry an enormous risk of osteoporosis, and therefore the indication for a preventive therapy with vitamin D and calcium should be established in every postmenopausal woman or after repeated steroid treatments.

Multiple Sclerosis: Immunotherapy

Given our current knowledge, there is a need for the early institution of immunomodulatory therapy, especially for patients with poor prognostic factors (motor and cerebellar symptoms, frequent disease exacerbations, and a high level of activity on magnetic resonance imaging ). Patients who progress despite immunomodulatory therapy should be reevaluated in terms of diagnosis, development of neutralizing antibodies, or compliance. If a patient has a partial response to immunomodulatory therapy but his or her disease, as assessed by clinical and MRI criteria, remains very active, every effort should be made to modify disease progression by searching for an immunosuppressive therapy regimen before irreversible and considerable disability has accumulated. For the majority of patients, multiple sclerosis (MS) is a chronic condition. Therefore, until a curative treatment has been developed, the available repertoire of immunosuppressive or immunomodulatory treatments should be assessed with respect to the possibility of long-term use. This is particularly important for new immunosuppressive drugs, such as cladribine or mitoxantrone, or for invasive procedures, such as total lymphoid irradiation or autologous bone marrow transplantation. For the latter treatments, experience with long-term administration is not available or the potential side effects (eg, cardiotoxicity with mitoxantrone) limit the cumulative dose. These considerations may limit long-term administration and thus the general usefulness of some drugs. Even with proven efficacy, we need to define the next step once treatment has to be discontinued. We should also address whether exacerbating disease by discontinuing an effective therapy is a potential hazard. What other therapeutic options remain once the current treatment is discontinued? Answers are not readily available at the moment, but the question should influence our decisions in the selection of traditional, well-studied or new, potentially promising therapies.

Prevention of experimental autoimmune encephalomyelitis in Lewis rats by a novel fungal source of gamma-linolenic acid

The effects of oral administration of linoleic- and gamma-linolenic-acid-rich oils on the clinical and histopathological manifestations of experimental autoimmune encephalomyelitis (EAE) were investigated in Lewis rats 7 d post-inoculation. gamma-Linolenic-acid-rich fungal (Mucor javanicus) oil at 500 mg/kg body weight abrogated clinical and histological signs of EAE although at doses of 200 and 1000 mg/kg body weight it was only effective in delaying the onset of clinical disease. Linoleic-acid-rich safflower-seed (Carthamus tinctorius) oil at 500, 750 and 1000 mg/kg body weight decreased the severity of clinical EAE disease in a dose-dependent manner. The effects in healthy animals of orally administered gamma-linolenic-acid-rich fungal oil (500 mg/kg body weight) and linoleic-acid-rich safflower-seed oil (1000 mg/kg body weight) on splenic lymphocyte proliferative responses to the T-cell mitogen concanavalin-A (Con A), membrane fatty acid composition and lymphocyte sub-sets were also studied. Both treatments enhanced the T-cell proliferative response to Con A. There was no significant effect on the proportion of splenic CD8+ or CD4+ lymphocytes. Compositional studies on splenic phosphoglyceride fatty acids of oil-treated animals suggest the above responses were associated with increases in spleen dihomo-gamma-linolenic and arachidonic acids.

Lecithin cholesterol acyltransferase in human cerebrospinal fluid: reduced level in patients with multiple sclerosis and evidence of direct synthesis in the brain

Several studies suggest that apolipoproteins and the low-density lipoprotein receptor are implicated in lipid transport in the brain. Given that cerebrospinal fluid has been reported to contain cholesteryl esterifying enzyme, and that lipid metabolism in the brain is abnormal in subjects with multiple sclerosis, we examined the cerebrospinal fluid from eight control subjects with a normal cerebrospinal fluid IgG index, and without active demyelinating disease, and from eight subjects (6 were diagnosed as having multiple sclerosis) with an increased IgG index and the presence of oligoclonal banding in the cerebrospinal fluid, for the presence of the enzyme lecithin cholesterol acyltransferase and apolipoprotein(a). None of the subjects demonstrated impairment of their blood-cerebrospinal fluid barrier, as estimated by the cerebrospinal fluid/serum quotient of albumin. Lecithin cholesterol acyltransferase was detected in the cerebrospinal fluid of all control subjects, being 0.12 +/- 0.06 microgram/ml (mean +/- SD) or about 2.2% of that in serum (5.4 +/- 1.4 micrograms/ml). The cerebrospinal fluid lecithin cholesterol acyltransferase index was 5.2 +/- 2.5, very similar to the cerebrospinal fluid index of apolipoprotein E, a protein known to be synthesized in the brain. Since lecithin cholesterol acyltransferase mRNA is also expressed in the brain, we can conclude that the protein is synthesized and secreted in the brain. The cerebrospinal fluid concentration of lecithin cholesterol acyltransferase in the subjects with active demyelinating disease or multiple sclerosis was only about one-half of that found in control subjects (0.06 +/- 0.02 microgram/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid and fatty acid composition is altered in plaque tissue from multiple sclerosis brain compared with normal brain white matter

Plaques and white matter from brains of multiple sclerosis (MS) patients were analyzed for lipid content, class composition, and fatty acid composition of total lipid, together with the fatty acid composition of plaque glycerophospholipids, and the results were compared with white matter from normal brain. Plaques contained less than 30% of the lipid present in normal white matter. Plaque lipid was characterized by significantly increased proportions of glycerophospholipids and decreased cerebrosides and sulfatides. In addition, a subacute plaque contained approximately 10 times the proportion of steryl esters observed in chronic plaques or normal white matter. Total lipid from all the MS plaques showed significantly increased percentages of saturated fatty acids, n-6, n-3 and total polyunsaturated fatty acids and decreased percentages of monoenes and alk-l-enyl ethers in comparison with normal brains. These results were consistent with increased cellularity and astrogliosis associated with MS plaques. However, analysis of plaque glycerophospholipids showed that the fatty acid changes observed in total lipid were not simply due to the increased proportion of glycerophospholipids and decreased myelin lipids, but that the fatty acid composition of the individual glycerophospholipids was different.

Red blood cell and adipose tissue fatty acids in mild inactive multiple sclerosis

The fatty acid profiles of phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) of the red blood cells of 30 patients with mild inactive multiple sclerosis (MS) and 30 healthy controls were studied by gas chromatography. The groups were well matched for factors likely to influence tissue lipid levels, including diet. The MS patients showed a significant reduction in PE eicosapentaenoic acid (p = 0.009) especially in women, and an increase in both PE dihomo-gamma-linolenic acid (p = 0.004) and PC stearic acid (p = 0.04). No reduction in linoleic acid was observed in either the PC or PE fractions of the MS subjects. A similar study of the fatty acid profile in adipose tissue in 26 MS and 35 healthy controls found no detectable eicosapentaenoic acid in either group. However, whereas docosahexaenoic acid was not detectable in any MS patient, 40% of the controls had measurable levels varying from to 0.1 to 0.3% of total estimated fatty acid (p = 0.0003). No reduction in linoleic acid in MS subjects was observed. Supplementation with oral fish body oil demonstrated that n-3 fatty acids were incorporated into red blood cells over 5 weeks and this occurred equally in MS and controls. The effects of oral supplementation on adipose tissue were studied after 1 and 2 years. Whereas many fatty acids such as linoleic acid were raised at 1 year, but did not rise subsequently, eicosapentaenoic acid and docosahexaenoic acid continued to rise through the 2-year period.(ABSTRACT TRUNCATED AT 250 WORDS)

Deficiencies of polyunsaturated fatty acids and replacement by nonessential fatty acids in plasma lipids in multiple sclerosis

Fatty acid compositions of plasma phospholipids, cholesteryl esters, triacylglycerols, and nonesterified fatty acids of 14 clinically proven and graded cases of multiple sclerosis were determined by capillary gas chromatography and compared with the values obtained for 100 normal, healthy subjects. In phospholipids, linoleic acid (18:2 omega 6; 18 carbon atoms, 2 double bonds, 6 carbon atoms beyond last double bond) was normal and 18:3 omega 6 was increased, but all subsequent omega 6 acids were subnormal (P less than 0.001), indicating impairment of chain elongation. All omega 3 acids were subnormal. The paucity of polyunsaturated fatty acids was compensated mass-wise by an increase in saturated acids. Disproportionate increases in short-chain, saturated, and monounsaturated acids, decreases in long-chain homologs, and increases of branched and odd-chain acids were observed. Loss of polyunsaturated fatty acids and replacement by nonessential acids lowered mean chain length and raised mean melting point significantly, suggesting that lowered membrane fluidity was only partially compensated by endogenous synthesis of lower-melting, nonessential acids. This phenomenon was not observed in cholesteryl esters or triacylglycerols. Nonesterified fatty acids showed significant changes in pattern of possible autacoid precursors. The abnormal profile of fatty acids in multiple sclerosis has features in common with profiles of other syndromes involving viral infections.

Red blood cell fatty acids in multiple sclerosis

The fatty acid (FA) composition of each phospholipid constituent of the red blood cells (RBC) was analyzed, by thin-layer and gas chromatography techniques, in 61 multiple sclerosis (MS) patients and 61 normal subjects, in whom the plasma lipid FA composition had previously been studied. The MS patients showed a significant decrease in the proportions of linoleic and arachidonic acids in most phospholipids, with a compensatory increase of saturated FA. Correlations between FA percentages in plasma and cell lipids demonstrated abnormalities in the MS patients, suggestive of a disturbance in the exchange between these compartments. The alterations reported in plasma and RBC in the MS patients are consistent with a relative deficiency of essential FA.

A double-blind controlled trial of long chain n-3 polyunsaturated fatty acids in the treatment of multiple sclerosis

A trial of n-3 polyunsaturated fatty acids in the treatment of multiple sclerosis has been conducted over a 5 year period. Ambulant patients (312) with acute remitting disease were randomly allocated to treatment or placebo. Both groups were given dietary advice to increase the intake of n-6 polyunsaturated fatty acids and the treatment group in addition received capsules containing n-3 polyunsaturated fatty acids. Analysis of clinical outcome at the end of 2 years of treatment was made in terms of the duration, frequency and severity of relapses and the number of patients who had improved or remained unchanged. The results showed no significant difference at the usual 95% confidence limits but there was a trend in favour of the group treated with n-3 polyunsaturated fatty acids in all parameters examined.

Plasma lipids and their fatty acid composition in multiple sclerosis

We report an extensive study of the plasma lipid profile and fatty acid composition in 61 multiple sclerosis (MS) patients compared with 61 normal subjects. The main abnormality in the MS was a reduction in the proportion of linoleic and arachidonic acids mostly evident in the HDL and in the cholesteryl esters fraction, with a compensatory increase in saturated acids. The fatty acid abnormalities correlated with the duration of the disease and the degree of disability. Thus, in the MS patients studied there was a deficiency in essential fatty acids, although this metabolic abnormality does not seem specific to MS.

Natural seric anti-fatty acid antibodies in multiple sclerosis

Naturally occurring anti-oleic acid conjugate antibodies were detected in human sera using an adapted direct immunoenzymatic assay. They were present to a higher level in the sera of patients with multiple sclerosis in acute relapse compared to patients with other neurological diseases or healthy subjects and even patients with multiple sclerosis in progressive form.

Red cell and hemorheological changes in multiple sclerosis

Blood rheology in multiple sclerosis (MS) was investigated in 15 subjects with varying degrees of locomotor difficulties who were members of the local MS Society. Control data were obtained from blood samples from 25 male and 25 female normal blood donors. Whole blood viscosity was measured and blood filterability was assessed. Six MS females provided blood samples for scanning electron microscopy. Erythrocyte membrane fatty acids and phospholipids were assayed. Whole blood viscosity in MS females was higher than controls at 3 of 4 shear rates (p less than 0.001) but in MS males blood viscosity was higher only at shear rate of 1.0 s-1 (p less than 0.05). MS erythrocyte filtration rates were significantly lower than controls (p less than 0.001). Leucocyte counts in MS were greater than controls both in males (p less than 0.01) and females (p less than 0.001). MS erythrocyte morphology was greatly different from controls (p less than 0.0001) and erythrocyte membranes contained less sphingomyelin than controls (p less than 0.01) but more phosphatidylinositol plus phosphatidylserine (p less than 0.02). We conclude that, because our findings indicate an identifiable and potentially correctable abnormality, it is possible to envisage an inhibition of the progressive nature of MS, with the hope of a better prognosis for patients.

Lipid peroxidation products and antioxidant proteins in plasma and cerebrospinal fluid from multiple sclerosis patients

Lipid peroxidation (LPx) products were measured as thiobarbituric acid-reactive substances (TS) and lipid-soluble fluorescent pigments (FP) in both plasma and CSF from MS patients and controls. Although no significant changes were found in MS plasma, we report here for the first time increases in both TS and FP in MS CSF (p less than 0.05 and p less than 0.01, respectively, compared with patients with other neurological diseases), indicating that increased LPx in CNS may be a feature of MS. Levels of transferrin were normal but caeruloplasmin (CP), a major antioxidant plasma protein, was significantly raised in MS patients (p less than 0.01) and this may represent an adaptive response to increased oxidative challenge. Neither of these proteins was detectable in CSF using radial immunodiffusion. There was no significant correlation between the severity or duration of the disease nor the period since the last relapse and either LPx products or CP suggesting that the changes observed in this work are not simply the direct result of demyelination and tissue damage.

Abnormalities of serum and plasma components in patients with multiple sclerosis

Qualitative and quantitative abnormalities in protein and non-protein components of serum and plasma in patients with multiple sclerosis have been the subjects of numerous reports. In this review many of the more recent observations are documented and evaluated. It is concluded that at present the welter of information that has been gathered does not contribute in any major, coherent way to our understanding of the etiology or pathogenesis of the disorder. Several of the abnormalities that have been observed may be future candidates for biochemical markers for multiple sclerosis; at present none is sufficiently reliable, distinctive or easily performed to warrant the status of a useful diagnostic or prognostic test.