A search for antibodies against glial cells in the serum and cerebrospinal fluid of patients with multiple sclerosis and Guillain-Barré syndrome

An appraisal of antigen identification and IgG effector functions driving host immune responses in multiple sclerosis

Increased immunoglobulin G (IgG) antibodies and oligoclonal bands (OCB) are the most characteristic features of multiple sclerosis (MS), a neuroinflammatory demyelinating disease with neurodegeneration at chronic stages. OCB are shown to be associated with disease activity and brain atrophy. Despite intensive research over the last several decades, the antigen specificities of the IgG in MS have remained elusive. We present evidence which supports that intrathecal IgG is not driven by antigen-stimulation, therefore provide reasoning for failed MS antigen identification. Further, the presence of co-deposition of IgG and activated complement products in MS lesions suggest that the IgG effector functions may play a critical role in disease pathogenesis.

Multiple sclerosis: Serum anti-CNS autoantibodies

BACKGROUND

It is uncertain whether there are autoantibodies detectable by indirect immunofluorescence in the serum of patients with multiple sclerosis (MS).

OBJECTIVE

To determine whether there are anti-central nervous system (CNS) autoantibodies detectable by indirect immunofluorescence in the serum of MS patients.

METHODS

Sera and in some cases cerebrospinal fluid from 106 patients with multiple sclerosis, 156 patients with other neurological diseases, and 70 healthy control subjects were examined by indirect immunofluorescence using cryostat sections of rat cerebrum fixed by perfusion with paraformaldehyde.

RESULTS

Autoantibodies were detected that recognized more than 30 neuronal, glial, and mesodermal structures in 28 of 106 MS cases. Most were also detected in patients with other related and unrelated neurological diseases and several were also found in healthy controls. Novel anti-CNS autoantibodies recognizing particular sets of interneurons were detected in both normal controls and in subjects with CNS diseases.

INTERPRETATION

Serum anti-CNS autoantibodies of diverse specificities are common in MS patients. The same anti-CNS autoantibodies are not uncommon in patients with other neurological diseases. The findings provide no support for the proposition that myelin breakdown in MS is caused by exposure of intact myelin sheaths or oligodendrocytes to a pathogenic serum anti-myelin or anti-oligodendrocyte autoantibody.

In vitro studies of glial cells: what can we learn about demyelinating diseases?

Acquired demyelinating diseases of the central and peripheral nervous systems comprise an important group of neurologic diseases of unknown etiology and incompletely understood pathogenesis. Cultures of glial cells are proving highly useful in investigating the role of both antibodies and cytokines in the pathogenesis of these disorders. While there clearly is need for comparative studies employing more complex systems and using patient derived tissues, glial cell cultures provide important advantages by allowing researchers to characterize the effect of cytokines and growth factors on specific cell types in controlled conditions.

Opsonization of normal myelin by anti-myelin antibodies and normal serum

Fc receptor-dependent myelin phagocytosis has been proposed as a possible important effector mechanism in several immune-mediated demyelinating diseases. The present study was designed to determine whether myelin is opsonizable by anti-myelin antibodies. Thioglycolate-elicited mouse peritoneal macrophages were cultured with 125I-labelled bovine central myelin pretreated with normal or immune serum. Serum opsonic activity was determined by a kinetic study comparing macrophage uptake of opsonized and untreated 125I-myelin. Heat-stable and heat-labile myelin opsonins were detected in normal rabbit serum. Myelin was also opsonized by normal rabbit gamma globulin and by heat-inactivated normal mouse, human, and guinea pig serum. Increased opsonic activity was detected in rabbit anti-myelin antiserum and the gamma globulin fraction prepared from this serum, in anti-myelin basic protein and anti-galactocerebroside antiserum but not in anti-myelin-associated glycoprotein antiserum or in serum from rabbits injected with Freund's adjuvant alone. One out of three anti-sheep red blood cell antisera tested also showed increased myelin opsonic activity. It is concluded that anti-myelin antibodies can promote opsonic phagocytosis, and that normal serum and normal serum gamma globulin also opsonize myelin.

Postmortem survival characteristics of rat glial cells in culture

Cell-type-specific markers and indirect immunofluorescence were used to determine the longest time interval between death of the animal and removal of tissues that permitted growth in vitro of rat central glial cells. Galactocerebroside+ oligodendrocytes could not be cultured after more than 1 hour had elapsed, whereas small numbers of glial fibrillary acidic protein (GFAP)+ astrocytes and GFAP- fibroblastic cells could still be cultured for as long as 6-7 hours after death. These observations may reflect a greater susceptibility of oligodendrocytes to anoxia compared with astrocytes and fibroblasts.

Comparison of in vitro demyelination and cytotoxicity of humoral factors in multiple sclerosis and other neurological diseases

The distribution and nature of serum factors causing in vitro demyelination and glial lysis were investigated in multiple sclerosis (MS), other neurological diseases (OND), ill control and control groups. MS sera were unique in affecting only CNS myelin and glia whereas stroke and Guillain-Barré syndrome (GBS) sera brought changes to both CNS and PNS tissue. Through both visual scoring of myelin damage and the quantitative measurement of radiolabel release from cerebellar cultures, it was evident that the MS and OND groups have similar myelino- and cytotoxic effects. This may reflect MS and OND sera sharing similar humoral factors. 74% MS, 68% OND and 22% of control scores were above a score threshold designed to exclude culture handling trauma effects. When classified by their current disease state MS patients with severe and mild disease yielded higher in vitro scores than did those with moderate disease who comprised an older age group. No other clinical features of MS patients gave any association with in vitro serum effects. The rare demonstration of bound Fab IgG in cultures after MS serum tests indicates that immune mechanisms are unlikely to make a large contribution to serum-induced demyelination and cellular change in vitro.

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.

Immune responses to myelin antigens in multiple sclerosis

Multiple sclerosis is considered to be a putative immunopathologic disease and there has been considerable effort over the years to prove an autoimmune etiology for it. To date, the evidence is all indirect and there is no proof of either antibody and/or cell-mediated hypersensitivity to any single identifiable CNS constituent whether a constituent of normal CNS or specific to the CNS of MS patients.

A review of the etiology of multiple sclerosis

The geographic distribution of multiple sclerosis and the influence of migration on the risk of contracting it point to an environmental factor as cause of the disease. This environmental factor might be a virus which might produce the demyelination process through an autoimmune reaction against components of the central nervous system. The other possible cause of multiple sclerosis is a genetic susceptibility, inferred from the higher risk for the disease found among relatives of patients with multiple sclerosis and on the association between the disease and some histocompatibility antigens of the HLA system. Both theories seem to be correct, with the environmental factors(s) causing multiple sclerosis only in the presence of a genetic susceptibility.

Rat CNS cell culture. Enhancement of neuronal survival and delay of glial proliferation by serum from patients with multiple sclerosis. A morphological study

The addition of serum from multiple sclerosis (MS) patients to the culture medium of dissociated cells from cerebral hemispheres of rat embryos caused a delay in glial proliferation and an enhancement of neuronal survival. Sera from normal individuals and patients with other neurological diseases failed to show this effect. These morphological observations are interpreted as the outcome of inhibition of in vitro gliogenesis.

Autoantibodies against pituitary peptides in sera from patients with multiple sclerosis

Autoantibodies against pituitary peptides were demonstrated in sera from multiple sclerosis (MS) patients. Ten patients with lupus erythematosus disseminatus (SLE) and 97 healthy blood donors served as controls. The sera were used as primary antibodies in the indirect immuno-enzyme cytochemical (IEC) method, with fixed, paraffin-embedded rat brains and rat and hog pituitaries as antigen substrates. Eleven of the 33 MS sera reacted with peptides in the neural lobe/hypothalamic nuclei or distal lobe. The MS had a significantly higher incidence of peptide antibodies than sera from controls (11/33 vs 9/97). The mean antibody titers were significantly different (1577 vs 333). Comparison with rabbit reference antibodies specific to each of the 6 distal lobe hormones showed that the 9 distal lobe-positive MS sera reacted with cells harboring peptides of the somatotropin family. The presence of peptide autoantibodies was not related to clinical status or medical treatment. No antibodies against pituitary peptides were found in the SLE sera. One of the 11 positive MS sera showed antibodies against gastric parietal cells. None of the 11 sera showed antibodies against muscle, mitochondria, thyroid, adrenal, or parotid antigens. We propose that in a proportion of patients with MS, these autoantibodies might be involved in the demyelinization process by interfering with the peptide/receptor interplay, thus placing MS as a disease in analogy with myasthenia gravis. Alternatively, these autoantibodies might be involved in the altered immunoregulation of MS or be secondary to the disease.

Abnormal serum factors in Guillain-Barré syndrome

The Guillain-Barré Syndrome (GBS) is generally considered to be a cell-mediated immunopathologic disease of the peripheral nervous system (PNS), although the evidence for this is indirect. Both in vitro and in vivo studies of sera from experimental animals with autoimmune demyelinating neuropathies suggest that serum factors, including antibodies to PNS myelin and/or Schwann cells, may be important in the pathogenesis of some of these disorders. More recently, similar in vitro and in vivo techniques, including the production of demyelination following intraneural injection in the rat have been employed to study sera from patients with GBS. The results of these studies demonstrate the presence of factor(s), as yet not fully characterized, that may be important in mediating demyelination. Moreover, in some patients with chronic or relapsing demyelinative inflammatory neuropathies and monoclonal gammopathy, there is evidence of antimyelin antibodies to PNS myelin. Further studies of serum from patients with acute GBS and these other neuropathies may clarify the role of serum factors in acquired inflammatory diseases of the PNS.

Invited review. Nervous system antigens

Some of the better characterized proteins (markers) of the nervous system are described. The availability of specific antibodies to these markers has allowed the localization and assay of the proteins in tissue and biological fluids. There is some evidence that autosensitization may occur. Clinical application of these markers includes the evaluation and prognostic significance after stroke and head injury. The diagnostic histopathological use of the markers in the investigation of various tumours is summarized.

Neural cell markers and their applications to neurology

Cell-type-specific antigenic markers which allow the unambiguous identification of the major neural cell types in dissociated cell cultures of central nervous system (CNS) and peripheral nervous system (PNS) tissues from a variety of animal species have recently been established. The use of many of these markers has also been extended to nervous tissue sections in which the in vivo properties of neural cells can be studied. Markers may be either cell surface or intracellular components of neural cells. Cell surface markers can be used to separate different cell types to produce purified cell populations. The ability of monoclonal antibodies to recognise single antigenic determinants is likely to prove superior to conventional heteroantisera in recognising cell surface antigens. Although the present techniques have intrinsic limitations, nonetheless both surface and intracellular markers should prove to be of great value in a wide range of biological and clinical neurological studies.

Immunofluorescent staining of rat brain glial cells with multiple sclerosis serum

Antibodies directed against glial cells may be involved in autoimmunity in multiple sclerosis (MS). Using a tissue culture system, the presence of glial cell antibodies in MS-patient serum was detected through immunofluorescent technique. Thirty one of 73 MS-sera were strongly positive for anti-glial cells, 13 were equivocal and 29 were negative. The antibody staining was either cytoplasmic or associated with cell surface membrane, and involved IgG type of antibody.

Multiple sclerosis serum and cerebrospinal fluid immunoglobulin binding to Fc receptors of oligodendrocytes

Suspensions of bovine oligodendrocytes were used to study the immunofluorescent staining properties of sera from multiple sclerosis (MS) patients and normal individuals. All sera (14 MS patients, 8 patients with other neurological diseases, and 11 normal individuals) showed positive oligodendrocyte staining by indirect immunofluorescence. Staining persisted after extensive absorption of sera with bovine liver to remove nonspecific binding. Similar findings were obtained for cerebrospinal fluid from all 5 MS patients as well as all 5 patients with other neurological diseases. In additional studies to determine if binding is mediated by the Fc fragment of IgG, results were: (1) ultracentrifuged normal and MS sera failed to react with oligodendrocytes, (2) positive staining with oligodendrocytes was observed after heat aggregation of IgG, (3) ox red blood cells, complexed with antibody, reacted with oligodendrocytes to produce strong rosette formation, and (4) the rosette formation could be blocked by prior treatment of oligodendrocytes with heat-aggregated IgG. The studies fail to support a previous claim for specific binding of immunoglobulins to oligodendrocytes in MS. However, they confirm and extend previous findings that the binding of IgG to oligodendrocytes may not necessarily be an antigen-antibody reaction. Therefore, adherence reactions with a putative antibody must exclude Fc-mediated binding.

The significance of anti-neuronal antibodies in Alzheimer's disease

Indirect immunofluorescence and cell-type-specific markers were used to determine whether antibodies directed against specific neural cell types were present in patients with Alzheimer's disease (AD), other neurological diseases (OND) and normal controls. Sera and cerebrospinal fluid (CSF) were tested on either frozen sections of rat and human cortex and/or dissociated cell cultures of neonatal rat cerebellum, and human fetal dorsal root ganglia (DRG). All groups of patients and normal subjects were indistinguishable in their pattern of immunoglobulin (Ig) staining. Staining of neurones on frozen sections was predominantly nuclear. In cultures all sera showed weak staining of oligodendrocytes, fibroblasts and Schwann cells. Varying degrees of surface staining of neurones were seen with both sera and CSF within all groups.

Do patients with demyelinating disease have antibodies against human glial cells in their sera?

Cell-type-specific markers and indirect immunofluorescence were used to study immunoglobulin binding to glial cells in dissociated cell cultures of human foetal optic nerve, spinal cord and dorsal root ganglion in sera from patients with demyelinating diseases, other neurological diseases and normal controls. These various sera proved to be indistinguishable in that almost all of them contained immunoglobulin which bound weakly to all oligodendrocytes and fibroblasts, 5-25% of astrocytes and about 50% of Schwann cells.