Cerebrospinal fluid and serum oligoclonal IgG bands in rabbits with experiment allergic encephalomyelitis

[Meningeal tertiary lymphoid organs: Major actors in intrathecal autoimmunity]

Multiple sclerosis (MS) is characterized by an intrathecal synthesis of immunoglobulins synthesized by B-cell clones and by a brain infiltrate of clonal T-cells. The clonal maturation of these lymphocytes takes place in tertiary lymphoid organs (TLO) developed in the intrathecal compartment. TLO are acquired lymphoid organs able to develop in the vicinity of the inflammatory sites, where they mount a complete antigen-driven immune response. We here review TLO pathophysiology in animal models of MS and human MS. Several pieces of evidence suggest that intrathecal TLO may play a major role in the clinical impairment. Potential therapeutic applications are examined.

Is multiple sclerosis an autoimmune disease?

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) with varied clinical presentations and heterogeneous histopathological features. The underlying immunological abnormalities in MS lead to various neurological and autoimmune manifestations. There is strong evidence that MS is, at least in part, an immune-mediated disease. There is less evidence that MS is a classical autoimmune disease, even though many authors state this in the description of the disease. We show the evidence that both supports and refutes the autoimmune hypothesis. In addition, we present an alternate hypothesis based on virus infection to explain the pathogenesis of MS.

Evidence for the role of B cells and immunoglobulins in the pathogenesis of multiple sclerosis

The pathogenesis of multiple sclerosis (MS) remains elusive. Recent reports advocate greater involvement of B cells and immunoglobulins in the initiation and propagation of MS lesions at different stages of their ontogeny. The key role of B cells and immunoglobulins in pathogenesis was initially identified by studies in which patients whose fulminant attacks of demyelination did not respond to steroids experienced remarkable functional improvement following plasma exchange. The positive response to Rituximab in Phase II clinical trials of relapsing-remitting MS confirms the role of B cells. The critical question is how B cells contribute to MS. In this paper, we discuss both the deleterious and the beneficial roles of B cells and immunoglobulins in MS lesions. We provide alternative hypotheses to explain both damaging and protective antibody responses.

EAE cerebrospinal fluid augments in vitro phagocytosis and metabolism of CNS myelin by macrophages

Previous studies from this laboratory have shown that CNS myelin is phagocytized and metabolized by cultured rat macrophages to a much larger extent when myelin is pretreated with serum containing antibodies to myelin constituents than when it is left untreated or pretreated with non-specific serum. In this study the effect of cerebrospinal fluid (CSF) from rabbits with experimental allergic encephalomyelitis (EAE) in promoting myelin phagocytosis was examined. Fourteen rabbits were immunized with purified myelin in Freund's complete adjuvant, seven of which developed clinical EAE symptoms. Serum and CSF were collected from EAE and control rabbits, and the CSF was centrifuged to remove cells. Sera and CSF from these rabbits and from Freund's adjuvant-immunized controls and untreated controls were measured for IgG content by radial diffusion assay, their myelin antibody characteristics were analyzed by immunoblots, and the ability of these serum and CSF samples to promote myelin phagocytosis when used for myelin opsonization was examined. The ability of a CSF sample to enhance radioactive myelin uptake and phagocytosis by cultured macrophages as measured by the appearance of radioactive cholesterol ester was linearly proportional to its total IgG titer, and correlated approximately both with clinical symptoms of the animal and the presence of antibody against the myelin constituents myelin basic protein, proteolipid protein, and galactocerebroside. The cholesterol esterification activities of EAE sera correlated to a lesser extent with IgG levels and clinical symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

HTLV-I-associated myelopathy: oligoclonal immunoglobulin G bands contain anti-HTLV-I p24 antibody

Human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM) and tropical spastic paraparesis belong to a new group of neurological diseases associated with retroviral infection. An HTLV-I-like virus has recently been implicated in multiple sclerosis as well. We studied paired cerebrospinal fluid and serum specimens from HAM and multiple sclerosis patients by isoelectric focusing and an isoelectric focusing HTLV-I p24 overlay technique to clarify the role of HTLV-I in these diseases. We detected oligoclonal bands by isoelectric focusing with silver-staining in cerebrospinal fluid, but not serum, from all 5 HAM and all 9 multiple sclerosis patients. An isoelectric focusing HTLV-I p24 overlay technique demonstrated anti-p24 antibody in HAM cerebrospinal fluid at a different pI distribution than that seen in paired serum, indicating local synthesis of anti-p24 antibody within the central nervous system. Oligoclonal bands in HAM cerebrospinal fluid corresponded in pI distribution to anti-p24 antibody activity, suggesting the presence of an ongoing HTLV-I infection in the central nervous system. Multiple sclerosis patients had no evidence of anti-HTLV-I activity by p24 radioimmunoprecipitation assay, Western immunoblots, or isoelectric focusing HTLV-I p24 overlay analysis. Our data support a role for HTLV-I as an etiological agent in HAM, but not in multiple sclerosis.

Experimental allergic encephalomyelitis (EAE): role of B cell and T cell epitopes in the development of EAE in Lewis rats

Studies from our laboratory have shown that classical clinical and histological signs of experimental allergic encephalomyelitis (EAE) may be induced in Lewis rats by synthetic peptides S49 or S55. Peptides S49S and S55S are defined by residues 69-84 and 72-84 of the guinea pig myelin basic protein (MBP), respectively. Peptide S53 (residues 75-84 of the guinea pig MBP), six residues shorter than S49S at the N-terminal end, induced mild clinical signs of disease unaccompanied by hind leg paralysis, incontinence, or central nervous system pathology. In contrast, peptide S67 (residues 69-81 of the guinea pig MBP), three residues shorter than S49S at the C-terminal end, did not induce either clinical or histological signs of EAE despite the fact that the S67-sequence houses an epitope known to induce cell-mediated immunity. Peptides S49S, S55S, and S53 are antigenic and gave rise to antibodies that recognized either of the three peptide sequences. In this report we explore the interrelationship between cellular immunity induced by the S67 sequence and humoral immunity, induced by the S53 sequence and the development of classical clinical and histological signs of EAE. The results show that the nonencephalitogenic sequence of S67 may be rendered encephalitogenic in the presence of antibody directed against the S53 sequence. Lewis rats immunized with S53 developed pathological signs of EAE only after they were challenged with S67. The fact that a simultaneous challenge with S67 and S53 was as effective in inducing EAE pathology as a delayed one (up to 40 days) suggests that the cellular response to S67 is dependent upon the humoral response to S53.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoglobulin and C3 abnormalities in acute psychiatric disorders

In a prospective study of 54 patients with acute psychiatric disorders, elevated absolute concentrations of immunoglobulin G (IgG), IgM and complement factor C3 were found in the cerebrospinal fluid (CSF) in seven (P less than 0.001), eight (P less than 0.01) and in four patients, respectively, and in serum in seven, 19 and 17 patients (P less than 0.001 in all), respectively, quantified by automated immunoprecipitin nephelometry in unconcentrated CSF and serum and compared with neurological controls with peripheral neurological symptoms. Elevation of the IgG-index was observed in seven patients (P less than 0.001) and CSF/S albumin ratio in four patients (P less than 0.05). The presence of oligoclonal IgG bands was found in 22 patients (P less than 0.001). The results suggest that viral infections, inflammatory and autoimmune processes may have significance in the etiopathogenesis of acute psychiatric disorders.

Opsonization with antimyelin antibody increases the uptake and intracellular metabolism of myelin in inflammatory macrophages

In most demyelinating diseases, macrophages are believed to be active agents of myelin destruction. In experimental encephalomyelitis, these cells appear to strip off and ingest the myelin lamellae, and myelin debris has been observed within the cell body. We show here in vitro conditions in which rat peritoneal macrophages phagocytose and metabolize CNS myelin lipids. Purified rat myelin, prelabeled in vivo with [14C]acetate, was incubated with preimmune serum or rabbit antiserum to rat CNS myelin and added to macrophage monolayers. Myelin opsonized with antimyelin antibodies was more readily phagocytosed and metabolized by cultured macrophages than untreated myelin or that preincubated with preimmune serum. In the presence of macrophages, levels of myelin polar lipids and cholesterol decreased, whereas radioactive cholesterol ester and triglyceride accumulated. Up to five times as much radioactive cholesterol ester and about twice as much triglyceride accumulated in macrophage cultures containing antibody-treated myelin as in cultures fed preimmune serum-treated myelin or in those incubated with untreated myelin. Both the fatty acid and the cholesterol from cholesterol ester contained radioactive label; therefore, both were derived at least partly from the radioactive myelin lipid. Antiserum to myelin purified from peripheral nerve was almost as effective as that to CNS myelin in stimulating cholesterol metabolism, whereas antiserum to galactocerebroside was about 70% as active. Antiserum to basic protein had less effect, whereas antiserum to the myelin-associated glycoprotein and proteolipid protein was inactive. Of the polar lipids, ethanolamine phosphatide was most degraded in both the antiserum- and preimmune serum-treated myelin, with the diacyl form and plasmalogen form degraded about equally. These experiments indicate that myelin-specific antibodies in inflammatory CNS lesions may participate in and stimulate macrophage-mediated demyelination.

Viruses and demyelinating disease of the central nervous system

In MS, there are many mechanisms by which viruses can produce demyelinating diseases in humans and experimental demyelinating infections in animals.

Immunological expression of gangliosides in multiple sclerosis and in a demyelinating model disease in rabbits

Accumulating evidence suggests that the process of demyelination in MS might involve an autoimmune response to one or more myelin components. A combination of myelin basic protein and myelin haptens was considered as possibly enhancing a cellular or humoral autoimmune reaction in MS. In line with this motion we have used an in-vitro E-rosette assay that correlates with in-vivo delayed hypersensitivity to demonstrate specific immunologic sensitivity of lymphocytes from MS patients to polysialogangliosides. A recent report that only lymphocytes from patients in relapse, but not in remission, are primed by gangliosides, underscores the relevance of the antigenic expression of gangliosides during the active pathological phase of the disease. The antigenic capacity of gangliosides to induce upon immunization a neurological disorder featured by demyelination in the CNS was demonstrated in rabbits. This and previous reports on the induction of peripheral demyelination in rabbits immunized with gangliosides will be further analyzed to gain insight on the possible role of these myelin lipid components as targets for an autoimmune mechanism in MS.

Anti I-A antibody suppresses active encephalomyelitis: treatment model for diseases linked to IR genes

To test the clinical relevance of monoclonal anti-I-A antibody in autoimmune disease, we investigated the effects of such a therapy in acute and chronic relapsing experimental allergic encephalomyelitis (EAE) by instituting treatment after the onset of paralytic signs and following the clinical course. In chronic relapsing EAE, animals treated with anti-I-As antibody had no mortality and fewer relapses when compared with control animals. Antibody levels to myelin basic protein were lower and histopathology showed milder lesions in the treated group. Similarly, in the acute EAE model, animals treated with anti-I-As antibody showed a dramatic reversal of paralytic signs and a rapid recovery. The mechanisms of action of antibody to IR gene products in autoimmune disease are discussed.

Silver staining of cerebrospinal fluid IgG in isoelectric focusing gels

A silver staining technique to be used on isoelectric focusing (IEF) gels for cerebrospinal fluid (CSF) oligoclonal IgG bands is described. The technique provides a sensitivity for detection of greater than 0.17 micrograms of IgG. The additional use of immunofixation with anti-human IgG antiserum rather than chemical fixation improves the sensitivity two-fold and permits identification of the oligoclonal bands as IgG. The technique enables one to focus small volumes of unconcentrated CSF (less than 40 microliters) and provides a powerful research tool.

Oligoclonal IgG in rabbits with experimental allergic encephalomyelitis: non-reactivity of the bands with sensitizing neural antigens

Oligoclonal IgG bands have recently been reported to occur in cerebrospinal fluid (CSF) and serum of rabbits with experimental allergic encephalomyelitis (EAE). To examine the specificity of these bands, a) individual bands eluted from rabbit CSF and sera were tested by radioimmunoassay (RIA) for anti-MBP activity and b) rabbit sera were absorbed with the neuroantigens used for sensitization. RIA of eluates from sequential agar gel slices of the entire IgG region of serum or CSF from MBP sensitized rabbits showed that anti-MBP activity occurred throughout the IgG region and did not localize to specific band-containing fractions. Furthermore, there was no change in banding patterns following absorption of EAE rabbit sera with washed brain homogenates, soluble MBP or MBP conjugated to Sepharose beads. Therefore, our results indicate that the oligoclonal IgG response in EAE is not preferentially directed against the sensitizing neuroantigen, and we raise the possibility of nonspecific B cell activation.

Demonstration of serum IgG antibodies against myelin during the course of relapsing experimental allergic encephalomyelitis in guinea pigs

Chronic relapsing allergic encephalomyelitis (r-EAE) was induced in a local strain of guinea pigs. By the use of isoelectric focusing (IF) followed by antigen immunofixation and autoradiography, antibodies directed against central nervous system (CNS) myelin were detected in 21 of 23 sera sampled during the course of r-EAE. Previous absorption of the sera with CNS myelin reduced or abolished antibody activity on autoradiograms. One r-EAE guinea pig developed definite oligoclonal IgG bands in serum while in 7 r-EAE animals faint oligoclonal IgG bands were present. The mobility of oligoclonal IgG bands differed from the mobility of antimyelin antibody bands on autoradiograms. The significance of these findings has not been definitely elucidated but the antimyelin antibodies may possibly be involved in the pathogenesis of the disease while oligoclonal IgG bands may represent an epiphenomenon not pathogenetically related to r-EAE.

Oligoclonal IgG in multiple sclerosis and subacute sclerosing panencephalitis brains

IgG was obtained from multiple sclerosis (MS) and subacute sclerosing panencephalitis (SSPE) brain materials by elution at neutral and acid pH, and by freezing and thawing. Serum, cerebrospinal fluid (CSF), and brain eluates were compared by isoelectric focussing (IEF) with sensitive peroxidase-anti-IgG staining. In 3 MS cases, different plaques or regions of the same brain had IgG patterns with some common and some different bands. Pooled white matter eluates contained the summation of bands seen in individual plaques or regions. Comparison of serum, CSF, and neutral and acid brain eluate IgG patterns showed many common bands but also unique bands. In two SSPE cases, eluates from different regions of the same brain showed virtually identical IgG patterns. Comparisons of serum, CSF, and neutral and acid eluates of the same brain also showed a common pattern of bands. Similarities in IgG patterns of sera, CSF, and regional brain eluates, from single cases of SSPE, suggest a common response to the same antigen in all regions or compartments. Differences in IgG patterns of sera, CSF, pooled brain eluates, and plaques or regional eluates from single cases of MS, suggest: either that (a) all MS oligoclonal IgG is "nonsense' antibody in terms of disease pathogenesis, or (b) much of the MS oligoclonal IgG is "nonsense' antibody, present as part of a specific oligoclonal immune reaction.

Oligoclonal IgG in the cerebrospinal fluid of guinea pigs with acute experimental allergic encephalomyelitis

The cerebrospinal fluid (CSF) of guniea pigs with experimental allergic encephalomyelitis was examined for the presence of oligoclonal IgG using polyacrylamide gel electrophoresis. Oligoclonal IgG (greater than or equal to 2 bands) was seen in the CSF obtained from 3/4 animals with experimental allergic encephalomyelitis induced by myelin basic protein and 2/3 with spinal cord-induced disease. It was not seen in CSF of 3 non-sensitized, 4 adjuvant-sensitized and 7 liver-sensitized guinea pigs. Scanning of stained gels confirmed the oligoclonal pattern. The bands were found in the region of gels which bound [125I]Staphylococcal Protein A. The data demonstrate that a non-infectious inflammatory reaction within the central nervous system can result in an oligoclonal IgG pattern in the CSF.