Serological techniques for detection of antibody to galactocerebroside

Evaluation of several adjuvants as alternatives to the use of Freund's adjuvant in rabbits

In three experiments we evaluated several types of adjuvants as an alternative to Freund's adjuvant (FA). In the first experiment three adjuvant preparations (a water-in-oil emulsion (Specol), a combination preparation of monophosphoryl lipid A + trehalose dimycolate + cell wall skeleton and a non-ionic block polymer surfactant (TiterMax)) were evaluated. The adjuvants were combined with three different types of weak immunogenic antigens (synthetic peptide, glycolipid and particulate antigen) and administered following the intramuscular and subcutaneous route. The evaluation was based on clinical, pathological and immunological parameters. The animals did not appear to be severely or chronically impaired by the experiment. After injection of the RIBI adjuvant, side effects of the same severity as with FA were induced, while low antibody titers were produced. TiterMax caused few side effects, while antibody responses were very low. In comparing Specol and FA, Specol had far fewer adverse effects than FA. However, Specol had immunostimulating properties of the same level as FA. In the second experiment, the effect of injected volume of FA on side effects and antibody titer was studied. Immunization of rabbits with a total of 0.5 ml FA at different sites does not seem to increase the immune response when compared with the immune response seen after injection of 0.5 ml FA at one site. However side effects were seen in all the animals. In the third experiment, the side effects following intradermal (i.d.) injection of the adjuvants were studied. After i.d. injection of FA or RIBI, undesirable effects were found. No side effects occurred after i.d. injection of Specol or TiterMax. From the studies it is concluded that Specol is an alternative to FA for hyperactivation of the immune response in rabbits.

Expression and induction of intercellular adhesion molecules (ICAMs) and major histocompatibility complex (MHC) antigens on cultured murine oligodendrocytes and astrocytes

Expression of intercellular adhesion molecule-1 (ICAM-1), ICAM-2-like molecule (Lgp55), and class I/II major histocompatibility complex (MHC) antigens (H-2 and Ia) was investigated in cultures of murine oligodendrocytes and astrocytes. Under unstimulated conditions, low levels of ICAM-1 expression were observed on astrocytes (less than 20%), but not on oligodendrocytes. Lgp55 was expressed intensely on oligodendrocytes (greater than 90%) and to a lesser degree on astrocytes (greater than 70%). A weak class I MHC (H-2) immunoreactivity was identified on both oligodendrocytes and astrocytes (50-70%). Class II MHC (Ia) antigen was undetectable on both cell types. After 48-hr exposure to immune mediators that include interferon-gamma (IFN-gamma), 500 U/ml, and supernatant from concanavalin A (Con A)-activated spleen cells, ICAM-1 expression was markedly increased on astrocytes (greater than 80%), but not on oligodendrocytes. Lgp55 expression on both cell types was not altered. Induction of H-2 antigen expression by immune mediators was quite high on both cell types (greater than 95%), while Ia antigen induction was low on astrocytes (less than 50%) and did not occur on oligodendrocytes. Cell type-specific expression and induction of ICAMs and MHC antigens by immune mediators may play roles in lymphocyte-glial cell interactions at the sites of inflammation in the central nervous system (CNS).

Axons induce differentiation of neurofibroma Schwann-like cells

Neurofibromatosis type 1 (NF-1, von Recklinghausen's disease) is characterized by the focal accumulation of Schwann-like cells (SLC) to form subcutaneous and plexiform neurofibromas and schwannomas. The aim of the present study was to determine whether NF-SLC are competent to differentiate in the presence of axons. Five dermal neurofibromas from five patients with NF-type 1 were enzymatically dissociated and the resultant cells were co-cultured with fetal rat dorsal root ganglion neurons. The cultures were studied by indirect immunofluorescence microscopy using antibodies against galactocerebroside (galC), P0 glycoprotein, human nerve growth factor receptor (NGFR) and human myelin-associated glycoprotein (MAG). SLC were strongly NGFR+ but galC- and MAG-SLC for the 2 weeks of coculture. After 3 weeks in vitro, SLC-NGFR was down-regulated but some of the spindle shaped cells had become galC+. MAG-SLC first appeared after 5 weeks in vitro but P0 glycoprotein was never detected when studied up to 6 weeks. Our data demonstrate that axons induce SLC to down-regulate surface NGFR and to express some myelin components in a qualitatively normal fashion.

Cytolysis of oligodendrocytes is mediated by killer (K) cells but not by natural killer (NK) cells

The cytotoxic activity of killer (K) cells against enriched cultures of bovine oligodendrocytes (BOL) was investigated in multiple sclerosis (MS) and controls. Human K cells mediated cytotoxicity to primary cultures of BOL in the presence of anti-BOL antiserum in all study groups, while BOL were resistant to human natural killer (NK) cells. Cytotoxic activity was significantly reduced in MS when compared to age-matched normal controls but not when compared to other neurologic disease (OND) patients. K cell-mediated lysis of BOL could also be induced with anti-galactocerebroside antibody but not with other antibodies including those specific for OL antigens (myelin basic protein, proteolipid apoprotein, and 2',3'-cyclic nucleotide 3'-phosphodiesterase). Enrichment of the effector population indicated that antibody-dependent cell-mediated cytotoxicity (ADCC) to BOL was mediated by large granular lymphocytes, and the effector population was further characterized by flow cytometry. The effector cells mediating ADCC could be inhibited by protein A of Staphylococcus aureus, and by K562 cells in cold competition assay. These observations indicate that oligodendrocytes are resistant to NK cells but are susceptible to cytolysis mediated by K cells. This may represent a potentially important immune mechanism in the pathogenesis of MS.

Lymphokines facilitate maturation of oligodendrocytes in vitro

As oligodendrocytes develop in vitro, A2B5+ progenitor cells acquire the oligodendrocyte-specific marker, galactocerebroside (GalC), to become A2B5+ GalC+ cells. They then gradually lose reactivity to A2B5, to become A2B5- GalC+ mature oligodendrocytes. By examining this developmental surface antigen expression with and without lymphokine stimuli we found that crude lymphokines, but not interleukin-2 or gamma-interferon, facilitate this maturation process. Thus, lymphokines may have a role in differentiation of oligodendrocytes. The same lymphokine stimuli, however, did not enhance the proliferation of oligodendrocytes.

Search for antibodies to galactocerebroside in the serum and cerebrospinal fluid in human demyelinating disorders

To determine if galactocerebroside (GalC) is a target antigen in the human demyelinating disorders multiple sclerosis, Guillain-Barré syndrome, and chronic demyelinating inflammatory polyneuropathy, we examined the serum and cerebrospinal fluid from patients with these disorders and from control subjects using four assay systems. In none of these assays could we detect significant differences in anti-GalC antibody titer between patients with demyelinating diseases and normal subjects or patients with other neurological disorders. Our data suggest that there is no humoral immune response to GalC in human demyelinating disorders.

Reactive glial cells in CNS demyelination contain both GC and GFAP

The glial cell response to anti-galactocerebroside (GC) induced demyelination of the cat optic nerve was studied using electron microscopy and immunocytochemistry. Oligodendrocytes, which are a primary target for anti-GC, were depleted in the early lesions but astrocytes survived and showed reactive changes. Astrocytic processes exhibited dual staining for both GC and glialfibrillary acidic protein, a feature not seen in astrocytes outside the lesion or in normal optic nerve. These reactive astrocytes did not stain for anti-myelin basic protein, nor did they contain myelin debris, making it unlikely that the GC immunoreactivity was due to phagocytosis of myelin. Rather, it is postulated that the presence of GC in these cells represents a process of dedifferentiation to a more primitive state in which both astrocytic and oligodendrocytic determinants are synthesised, and that these reactive glial cells may be precursors of a new population of remyelinating oligodendrocytes.

Owl monkey astrocytoma cells in culture spontaneously produce infectious JC virus which demonstrates altered biological properties

A tumor cell suspension of an explanted JC virus (JCV)-induced owl monkey glioblastoma was inoculated intracranially into four recipient juvenile owl monkeys. Twenty-eight months following inoculation one owl monkey developed a glioblastoma, which was explanted into tissue culture. DNA from both the tumor tissue and tumor cells in culture hybridized to a JCV DNA probe by Southern analysis, indicating that free, as well as integrated, viral DNA may be present. At the time of the second culture passage, viral JCV DNA was extracted from these cells and cloned into a plasmid vector. Nucleotide sequencing of the regulatory region of the cloned DNA demonstrated homology with the prototype Mad-1 strain of JCV and revealed a 19-base-pair deletion in the second 98-base-pair tandem repeat that eliminated a second TATA box. This deletion is characteristic of the Mad-4 strain of JCV, which is highly neurooncogenic. By the third culture passage, 100% of the cells were T-antigen positive. Approximately one-third of the cells in culture hybridized to a biotinylated JCV DNA probe when in situ hybridization was used, a technique that only detects high-copy-number of replicating viral sequences. By the culture passage 5 and continuing through culture passage 14, viable JC virions could be recovered. The T protein synthesized by this virus, now termed JCV-586, differed from both the Mad-1 and Mad-4 strains in that it formed a stable complex with the cellular p53 protein in the tumor cells. Also, the JCV-586 T protein reacted to several monoclonal antibodies made to the simian virus 40 T protein that were not recognized by either the Mad-1 or Mad-4 strains.

Production and characterization of high titer antibodies to galactocerebroside

High titer antibodies primarily of the IgG class were produced against galactocerebroside (GalC) by including keyhole limpet hemocyanin (KLH) and supplemental M. tuberculosis in the adjuvant mixture used for immunization of rabbits. Antibody titers were determined by an ELISA in which microtiter wells were coated with liposomes containing lecithin, cholesterol and GalC. The antibodies showed reactivity with GalC and psychosine, but not glucocerebroside, sulfatide, mixed gangliosides or asialo GM1. Specificity was further demonstrated by absorption of antibodies with GalC. Binding was inhibited by galactose, but only at high concentrations. Further, the antibodies did not bind to any brain proteins on immunoblots, indicating lack of reactivity with glycoproteins which might contain a terminal galactose. Antibodies to GalC are directed against different determinants than those reacting with peanut agglutinin since the lectin will not react with GalC, and the antibodies will not react with asialo GM1. The antibodies raised to GalC by this method show specific staining for oligodendroglia in culture. Peanut agglutinin binds intensely to process-bearing GalC+ oligodendroglia, but very poorly to the membrane sheets elaborated by oligodendroglia after longer times in culture. Other process-bearing GalC-, GFAP- cells were also stained with peanut agglutinin; these cells may represent glial precursors.

Schwann cell galactocerebroside of unmyelinated fibers is inducible by derivatives of adenosine 3',5'-monophosphate

By using indirect immunofluorescence, galactocerebroside (galC) was detected on the surface of Schwann cells cultured from unmyelinated fibers of 10- to 12-day-old rat cervical sympathetic nerve trunk. By day 4 in vitro, galC-positive cells disappeared from the culture. When the 4-day cultures were treated with 1 mM 8-bromo cyclic AMP or dibutyryl cyclic AMP, galC reappeared in 72 h. The proportion of Schwann cells expressing galC was dependent on the concentration of cyclic AMP derivatives used.

Fluorescence-activated cell sorter analysis of bulk-isolated porcine oligodendrocytes

We describe here the methods by which enriched populations of oligodendrocytes were isolated from adult porcine brains using Percoll density gradient centrifugation and their immunological properties analyzed by a fluorescence-activated cell sorter (FACS). The analyses by immunofluorescence microscopy and FACS indicated 95% and 93% purity of oligodendrocytes in the cell preparations when galactocerebroside antibody, an oligodendrocyte-specific marker, was employed. Further FACS analysis indicated that 90% of the cells with the forward angle light scatter characteristics of oligodendrocytes were immunolabelled by the monoclonal antibody HNK-1. The FACS sorting capability was then used to correlate the forward angle light scatter and propidium iodide uptake characteristics of our cell preparations to cell debris, erythrocytes as well as viable and non-viable oligodendrocytes. By gating on a multiparameter basis on both defined forward light scatter and positive galactocerebroside immunolabelling, oligodendrocyte populations exceeding 98% purity were obtained which were suitable for long-term culture and further immunological and neurobiological studies.

Remyelination follows antibody-induced central nervous system demyelination

Remyelination after anti-galactocerebroside-induced demyelination in the guinea pig optic nerve was evident 17 days after the onset of demyelination. The tempo of remyelination was uniform for large- and small-diameter axons and progressed, with compaction and thickening of myelin sheaths. Demyelinated axons were found interspersed among remyelinated fibers and were consistently separated from oligodendrocytes by astrocytic processes. These findings indicate that central nervous system remyelination may occur after in vivo antibody-induced demyelination, but that new myelin formation may be limited by mechanical interference from astrocytic processes.

The expression of MHC antigens on oligodendrocytes: induction of polymorphic H-2 expression by lymphokines

Neither class I nor class II major histocompatibility complex (MHC) antigen has been demonstrated in native oligodendrocytes, the possible target of viral or immune damage in multiple sclerosis (MS). In this report, we show that H-2, but not Ia, antigen expression is induced on isolated mouse oligodendrocytes in vitro by crude supernatant from lectin-activated spleen cells, lectin-free interleukin 2, and cloned gamma-interferon. This induction of H-2 expression is not accompanied by proliferation of oligodendrocytes, whereas MHC induction in spleen cells is highly related to their proliferation, or blastoid transformation. Oligodendrocytes as well as other brain cells are probably isolated from these lymphokines by the blood-brain barrier (BBB). However, it is possible that oligodendrocytes express MHC class I antigen as a consequence of impairment of the BBB, or in the presence of activated T-cells which have been demonstrated in active MS lesions. This activation then renders oligodendrocytes possible target cells for MHC-restricted cytotoxic T-cells.

Relation of clinical, serological, morphological, and electrophysiological findings in galactocerebroside-induced experimental allergic neuritis

Rabbits were immunised repeatedly with bovine brain galactocerebroside. Almost all animals developed overt polyradiculoneuropathy. Circulating IgG antibodies to galactocerebroside in the serum and deposits of IgG in the spinal roots were detectable weeks before definite clinical, morphological, and electrophysiological alterations occurred. The levels of IgG antibody titres to galactocerebroside did not correlate with the severity of the clinical disease and of nerve conduction slowing. Remyelination and a virtually complete recovery of nerve dysfunction occurred although circulating antibodies to galactocerebroside were still present.

Normal myelination of regenerating peripheral nerve sprouts despite circulating antibodies to galactocerebroside in rabbits

Rabbits were immunized with galactocerebroside and a crush lesion was created in the tibial nerve before the onset of experimental allergic neuritis. Normal regeneration and myelination of distal peripheral nerve sprouts occurred and was identical to that of controls, although circulating antigalactocerebroside antibodies were present and nerve roots showed typical signs of beginning experimental allergic neuritis.

Emergence of three myelin proteins in oligodendrocytes cultured without neurons

Oligodendrocytes, the myelin-forming cells of the central nervous system, were cultured from newborn rat brain and optic nerve to allow us to analyze whether two transmembranous myelin proteins, myelin-associated glycoprotein (MAG) and proteolipid protein (PLP), were expressed together with myelin basic protein (MBP) in defined medium with low serum and in the absence of neurons. Using double label immunofluorescence, we investigated when and where these three myelin proteins appeared in cells expressing galactocerebroside (GC), a specific marker for the oligodendrocyte membrane. We found that a proportion of oligodendrocytes derived from brain and optic nerve invariably express MBP, MAG, and PLP about a week after the emergence of GC, which occurs around birth. In brain-derived oligodendrocytes, MBP and MAG first emerge between the fifth and the seventh day after birth, followed by PLP 1 to 2 d later. All three proteins were confined to the cell body at that time, although an extensive network of GC positive processes had already developed. Each protein shows a specific cytoplasmic localization: diffuse for MBP, mostly perinuclear for MAG, and particulate for PLP. Interestingly, MAG, which may be involved in glial-axon interactions, is the first myelin protein detected in the processes at approximately 10 d after birth. MBP and PLP are only seen in these locations after 15 d. All GC-positive cells express the three myelin proteins by day 19. Simultaneously, numerous membrane and myelin whorls accumulate along the oligodendrocyte surface. The sequential emergence, cytoplasmic location, and peak of expression of these three myelin proteins in vitro follow a pattern similar to that described in vivo and, therefore, are independent of continuous neuronal influences. Such cultures provide a convenient system to study factors regulating expression of myelin proteins.

Neuroimmunology of gangliosides in human neurons and glial cells in culture

Gangliosides (sialic-acid-bearing glycolipids) have received attention in recent years because of their role in cell recognition phenomena, synaptic transmission, memory generation, and nerve regeneration in the fields of neurosciences. It is suggested that each brain region or each neural cell type may contain a specific and characteristic set of gangliosides. We have investigated the immunocytochemical localization of several classes of gangliosides that include GM1, GM4, GD3, and GQ gangliosides on the cell surface of various cell types found in human neural cell cultures with antibodies specific for these gangliosides. Cell cultures were obtained from adult human brains and fetal human dorsal root ganglia and spinal cord and cultured in vitro for the period up to 6 months and utilized for the ganglioside immunocytochemistry. It was demonstrated that GM1 ganglioside was present in all galactocerebroside-positive oligodendrocytes and most of glial fibrillary acid protein (GFAP)-positive astrocytes (80%), most of neurofilament-positive neurons (80%), 50-70% of Schwann cells, and 5-10% of fibronectin-positive fibroblasts; GM4 ganglioside could be detected in all oligodendrocytes, 80% of astrocytes, and 50% of Schwann cells, while no staining was found in neurons or fibroblasts; GD3 ganglioside was present in all oligodendrocytes and 5-10% of astrocytes but not in neurons, Schwann cells, or fibroblasts; and all of fetal CNS neurons and approximately 80-90% of fetal dorsal root ganglia (DRG) neurons and a small percentage of astrocytes (10-20% in fetal and less than 1% in adult astrocytes) was labeled by A2B5 antibody which is specific for GQ ganglioside, while this antibody did not stain cell surface of oligodendrocytes, Schwann cells, or fibroblasts. Three classes of gangliosides, GM1, GM4, and GD3 were found to be definite components of fetal and adult human oligodendroglial plasma membrane, while GM1 and GM4 gangliosides were detected on the surface of most astrocytes. Only a minor population of astrocytes from both fetal and adult human CNS contained GD3 and GQ gangliosides. Two classes of gangliosides, GM1 and GQ, were detected on the surface of fetal human neurons. More than half of fetal Schwann cells reacted to GM1 and GM4 antibodies but did not to GD3 or GQ antibodies. We recognized the presence of a specific and characteristic set of gangliosides on the cell surface of different human neural cell types and these findings should facilitate further investigation of the precise biological activity of these gangliosides.

Expression of H-2 antigen on oligodendrocytes is induced by soluble factors from concanavalin A activated T cells

It has been shown that soluble factors from activated T cells, or interferon alone, enhance the expression of major histocompatibility complex (MHC) antigens in several cell types. In this study we have demonstrated, by means of indirect immunofluorescence and radioimmunoassay, that the expression of mouse MHC class I antigen (H-2) on isolated mouse oligodendrocytes is induced by soluble factors from concanavalin A activated T cells. Autoradiographic studies indicate that this induction of H-2 expression is not accompanied by proliferation of oligodendrocytes.

Galactocerebroside antiserum causes demyelination of cat optic nerve

A model of immune-mediated optic nerve demyelination is described. Micro-injection of small volumes (less than 5 microliter) of high titer polyclonal anti-Gal-C serum into the cat optic nerve resulted in a focal, highly selective demyelinative lesion followed by remyelination. Demyelination appears to be due to a dual effect on myelin and on oligodendrocytes. The numbers of these cells within the lesion were initially reduced but subsequently increased as remyelination occurred.

Transient expression of glial fibrillary acidic protein in developing oligodendrocytes in vitro

Expression of galactocerebroside (GC) and glial fibrillary acidic protein (GFAP) was studied in oligodendrocyte-enriched cultures of newborn mouse brains. In the cultures, GC was detectable as early as 1 day in vitro (1-DIV). Using double immunofluorescence labeling, some GC-positive cells were also stained homogeneously by the anti-GFAP serum. The intensity of GFAP staining increased until 9-DIV when the GC-positive cells revealed the typical morphology of oligodendrocytes, and the GFAP staining faded thereafter. The GFAP staining pattern of the GC-positive cells was not changed upon exposure to demecolcine, even though the GC-negative, GFAP-positive astrocytes showed perinuclear aggregation of GFAP. No intermediate filaments were observed in the oligodendrocytes by electron microscopy. The results suggest that the oligodendrocytes may have soluble GFAP in a certain period of early development.

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.

The differentiation of oligodendrocytes in a serum-free hormone-supplemented medium

Primary mixed cultures of trypsin-dissociated fetal and newborn rat brain and spinal cord have been grown in a serum-free medium. This medium, containing insulin, selenium, transferrin and triiodothyronine, was optimized for oligodendrocyte survival by determining the number of cells which expressed surface galactocerebroside. Comparison of cultures in serum-containing and serum-free media revealed that galactocerebroside positive (GalC+) oligodendrocytes could be detected earlier in the absence of serum. This early differentiation occurred in the absence of the added hormones and nutrients, whose main function appeared to be to prolong survival of the cells. The effect of serum on the differentiation of oligodendrocytes was studied by comparing the expression of surface GalC in media containing 2.5% or 10% fetal calf serum. At a given time a much greater number of GalC+ oligodendrocytes could be detected at the lower serum concentration. However, when cultures were transferred from 10% serum to serum-free medium (or 1% serum) large numbers of GalC+ oligodendrocytes subsequently appeared, showing that precursors were present in the high-serum medium, but that they were unable to differentiate. Possible explanations of the effect of serum on oligodendrocyte differentiation are discussed.

The mitotic history and radiosensitivity of developing oligodendrocytes in vitro

By use of pulse-chase exposure of dissociated cells of rat fetal spinal cord or brain to [3H]thymidine (TdR) and unlabeled TdR it has been shown that oligodendroglial precursors which do not express galactocerebroside (GalC) divide first and later differentiate to express GalC. The rate of proliferation of more mature GalC+ oligodendrocytes is considerably lower than that of their GalC- precursors. It has been found that oligodendrocyte precursor cells are extremely sensitive to [3H]TdR irradiation. Exposure to as little as 0.03 microCi/ml for 24 hr proved to be harmful, particularly during a critical period before birth. This critical period corresponded to the peak of division of oligodendrocyte precursor cells.

Experimental demyelinating optic neuropathy induced by intra-neural injection of galactocerebroside antiserum

The morphological changes induced by microinjection of galactocerebroside (Gal-C) antiserum into the rat optic nerve are described. Light and electron microscopic observations were made 2-20 days post-injection. The severity and extent of the lesion varied according to the volume of antiserum injected and the depth of penetration into the nerve. With small volumes of antiserum (1-3 microliters), primary demyelination was the principal change found from 2 days onwards and by 10 days there was evidence of remyelination by oligodendroglia. Some fibres undergoing Wallerian-type degeneration were also found. The injection of larger volumes of antiserum (5-10 microliters) produced a more extensive lesion with marked axonal degeneration in addition to demyelination at the periphery of the lesion. These findings show that Gal-C antiserum can cause demyelination of central nerve fibres when the blood-brain barrier is bypassed.

Rapid alterations of the axon membrane in antibody-mediated demyelination

Alterations of nodal and paranodal axolemma of the rat sciatic nerve were investigated in antigalactocerebroside serum-induced demyelination. A ferric ion-ferrocyanide (FeFCN) stain that appears to stain the regions with a high sodium channel density in nerve fibers was applied. When acute conduction block was initiated 20 to 180 minutes after the antiserum injection, myelin terminal loops began to be detached from the paranodal axolemma and reaction product of FeFCN stain originally localized at the nodes decreased in density and extended to the paranodal axolemma. By the time that complete conduction block was established, 5 hours after the injection, FeFCN stain was barely detectable around the nodal area. The loss of staining was associated with detachment and vesiculovacuolar degeneration of the paranodal myelin. This rapid deterioration and disappearance of normal cytochemical characteristics of the axolemma in the presence of only modest paranodal demyelination could be a morphological correlate of the loss of excitability of the axon membrane.

Antigalactocerebroside serum demyelinates optic nerve in vivo

Antiserum to the myelin lipid galactocerebroside (GalC) causes rapidly progressive focal demyelination when injected into guinea pig optic nerves. The capacity of anti-GalC to induce central nervous system demyelination is complement-dependent, and demyelinating activity is present in the immunoglobulin fraction of anti-GalC serum. Demyelination appears to result from primary damage to oligodendrocytes.

Differentiation and transformation of neural plate cells

The developmental potential of presumptive neural plate cells of prestreak chick embryos (stage 1) and neural plate cells from definitive streak chick embryos (stage 4) has been examined in cell culture using specific markers that identify the major cell types in the vertebrate central nervous system. The prestreak presumptive neural plate (PSPNP) cells, stage 1, assume an epithelial appearance in vitro and synthesize cellular fibronectin, but do not express markers for the neuronal, astrocytic, melanocytic, or oligodendrocytic lineages. Conversely, definitive-streak neural plate (DSNP) cells contain precursors which express cell-type-specific markers for terminally differentiated neurons, astrocytes, and melanocytes, and synthesize an extracellular matrix of cellular fibronectin. Differentiation of DSNP cells in vitro can be prevented by infection with a temperature-sensitive mutant of Rous sarcoma virus (RSV), tsNY68. Differentiation of DSNP cell transformants can be resumed by a temperature shift to the nonpermissive temperature. The morphological and biochemical changes associated with tsNY68 transformation are accompanied by alterations in pp60src kinase activity in the transformed cells.

Human alpha-fetoprotein-rich fraction inhibits galactocerebroside antibody-mediated lysis of oligodendrocytes in vitro

Polyclonal rabbit antiserum to galactocerebroside (anti-GalC) produces titer-dependent lysis of cultured Percoll-isolated bovine and rat oligodendrocytes. In this study anti-GalC produced complement-dependent lysis of 76% of the bovine cells and 65% of the rat cells maintained for 3 to 6 days in vitro. With the concomitant addition of human umbilical cord serum fractions containing fetal alpha-fetoprotein (AFP), lysis was decreased to 31% and 39%, respectively. Control antisera (anti-complete Freund's adjuvant/albumin) showed a cytotoxicity index of 15% for bovine cells and 23% for rat cells. Neither albumin, nor normal human serum, nor any of several pregnancy-associated hormones reduced the lysis produced by anti-GalC. AFP-rich fraction reduced oligodendrocyte lysis when mixed with anti-GalC or complement, but not when first incubated with the cells. Similar findings were obtained when AFP was assayed in specific oligodendrocyte radioimmunoassays utilizing anti-GalC antibody. Our experiments indicate that AFP activity may result from its binding to anti-GalC antibody; it is possible that the Fc portion of the antibody is involved. These data provide in vitro evidence of a possible immunosuppressive role of AFP in the central nervous system.

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.

51Cr release cytotoxicity radioimmunoassay to detect immune cytotoxic reactions to rat Schwann cells in vitro

Monolayers of rat Schwann cells incubated with 51Cr were used as targets for a cytotoxicity assay employing rabbit antiserum to galactocerebroside (R anti-GalC). Specific 51Cr release was demonstrated which was heat sensitive and complement-dependent. The assay was readily performed, reproducible and quantitative, and should prove useful in assessing anti-Schwann cell cytotoxic activity of experimental and human serum.

A quantitative analysis of cell surface glycosphingolipid with a fluorescence activated cell sorter

The fluorescence activated cell sorter (FACS) was used with an indirect membrane immunofluorescence technique to detect antibody against the Forssman antigen, a glycosphingolipid. Sheep erythrocytes, which contain Forssman antigen as a major membrane glycosphingolipid, were used as the target antigen. Detection of the anti-Forssman antibody on the sheep erythrocytes was done with specific fluorescein-conjugated second antibody and analyzed on a FACS. Compared to other available methods, analysis with the FACS was simple, sensitive, reproducible and quantitative. More than 250 pg of antibody could be detected. In addition, as little as 1 ng of Forssman antigen could be estimated by a binding inhibition experiment.

The ultrastructure of isolated rat oligodendroglial cell cultures

Cultured rat oligodendrocytes were studied by transmission electron microscopy. Cells were identified by an immunocytochemical stain for galactocerebroside, a specific cell surface marker for oligodendroglial cells. Oligodendroglial cell perikarya contained numerous ribosomal rosettes, microtubules, prominent networks of cisternae of the Golgi apparatus and residual bodies. Glycogen and intermediate filaments were absent. Oligodendrocytes gave rise to numerous processes. Pentalaminar and heptalaminar profiles, consistent with tight and gap junctions, were seen between plasma membranes of processes and between perikarya and processes. The cell surface of processes showed numerous gross ruffles which stained for galactocerebroside. Similar membranous profiles appeared in the vicinity of oligodendroglial processes and suggested to us that the plasma membrane of certain of its components may be released into the medium. We concluded that cultured rat oligodendrocytes maintain many similarities with oligodendrocytes in situ and, therefore, are valid models for morphologic, physiologic and biochemical studies.

Preparation of anti-GM4 antiserum and its assay by a solid-phase radioimmunoassay

Anti-GM4 antiserum was prepared from rabbits by immunization with pure human brain GM4 ganglioside in complete Freund's adjuvant and methylated bovine serum albumin. None of the immunized animals developed any clinically apparent neurological dysfunction. The antiserum titer and specificity were analyzed by double immunodiffusion and a novel solid-phase radioimmunoassay (RIA). In the latter procedure, microtiter plate wells were coated first with the glycolipid antigen, followed by sequential application of antiserum and [125I]-Staphylococcal Protein A. The absorbed radioactivity in the well was then counted. Employing the RIA procedure, anti-GM4 antibody achieved a titer of 1:1600. The antiserum also exhibited a high degree of specificity to GM4; cross-reactivity with glycolipids of similar structure was negligible. The production of highly specific antiserum to GM4 and the feasibility of detecting antibodies to glycolipid antigens by a convenient solid-phase RIA should be useful to further study the biological and immunological roles of GM4 and other glycolipids in the central nervous system.

Acute conduction block associated with experimental antiserum-mediated demyelination of peripheral nerve

Intraneural injection of antisera from rabbits with high antigalactocerebroside antibody levels into rat sciatic nerve produced acute nerve conduction block. This was first apparent in some motor axons between 30 and 60 minutes after injection and progressed to completion within 2 to 4 hours. Concurrent morphological evidence of demyelination was present, but structural changes at the time of onset of block were mild and were restricted to the myelin and Schwann cell, particularly at the paranodal areas and Schmidt-Lanterman clefts. It is suggested that paranodal lesions could account for the observed conduction block.

A simple method to measure anti-glycolipid antibody by using complement-mediated immune lysis of fluorescent dye-trapped liposomes

A simple, reproducible, and micro quantity method is described to measure the antibody against glycolipid antigens. The multilamellar liposomes containing carboxyfluorescein (CF), which is self-quenched at high concentration, are prepared by vortexing the dried lipid films consisting of egg lecithin, cholesterol, phosphatidic acid and Forssman glycolipid antigen. On addition of anti-glycolipid serum plus active complement, liposome lysis occurs, and trapped CF is released. The dilution of CF in the external volume abolishes the quenching, resulting in a high fluorescence signal. Experimental conditions to measure anti-glycolipid antibody is established in this paper.

Anti-ganglioside antibodies in multiple sclerosis

Serological activity against several purified brain gangliosides has been demonstrated in sera of a proportion of multiple sclerosis patients, but not in normal individuals. The activity was determined by the capacity of the sera to bring about complement-dependent lysis of liposomes containing the respective ganglioside in their lipid bilayer. An apparent correlation is indicated between the severity of the disease and the extent of liposome lysis. Cerebrospinal fluid of the patients did not induce lysis, probably due to low antibody concentration.

Antiserum induced myelination inhibition in vitro without complement

Exposure of neonatal rat cerebellum cultures to antiserum to whole spinal cord or galactocerebroside inhibited myelin formation regardless of whether guinea pig serum was added fresh or after heating to 56 degrees C for 1 h in order to achieve complete removal of hemolytic complement activity. Myelination followed removal of antisera from the culture media. This suggests that the inhibition of primary myelination by anti-CNS tissue antiserum occurs through some mechanism other than as the result of a cytotoxic reaction against oligodendrocytes mediated via the complement system.

Immune response to isolated oligodendrocytes

Oligodendrocytes were isolated from bovine white matter and were injected with complete Freund's adjuvant (CFA) into experimental animals. Indirect immunofluorescence studies using fluoresceinated goat anti-rabbit or anti-guinea pig immunoglobulin (GARIg; GAGPIg) showed that rabbit and guinea pig anti-oligodendrocyte (RAO, GPAO) sera reacted specifically with the surface of isolated oligodendrocytes in suspension, as well as with oligodendroglia in bovine and human brain sections, and in mouse cerebellum cultures. This activity of RAO was blocked by non-fluoresceinated GARIg and by GPAO, and absorbed by oligodendrocyte preparation (OP) or whole white matter, but not by purified myelin, neuroblastoma or non-brain tissue. Low levels of anti-basic protein antibodies were found in many RAO (but not GPAO) sera by radioimmunoassay, and a few showed significant anti-galactocerebroside antibody by agglutination and radioimmunoprecipation techniques. Guinea pigs sensitized with isolated oligodendrocytes in CFA showed cell-mediated immunity (CMI) to OP as manifested by delayed type skin test and induced in vitro lymphocyte transformation. CMI to purified myelin basic protein was not detected. The demonstration of humoral and CMI to the cell responsible for the production of CNS myelin may be related to some aspects of the immunopathogenesis of demyelinating disorders.

Experimental allergic neuritis induced by sensitization with galactocerebroside

Thirteen of 31 rabbits immunized repeatedly with bovine brain galactocerebroside developed experimental allergic neuritis, manifested by flaccid paresis and hypesthesia of four limbs, 2 to 11 months after the initial inoculation. Electrophysiological studies revealed multifocal conduction block of peripheral nerves. Perivenular demyelinative lesions associated with phagocytic mononuclear cells occurred in spinal ganglia, roots, and less frequently in distal nerves.

Antibodies to galactocerebroside bind to oligodendroglia in suspension culture

Antisera raised in rabbits against galactocerebroside bind to bovine oligodendroglia in suspension in significant titer as demonstrated by indirect immunofluorescence. Absorption of antigalactocerebroside antiserum with galactocerebroside, oligodendroglia, or myelin markedly reduces the antigalactocerebroside antibody titer as measured by a radioimmunoprecipitation test as well as the binding to oligodendroglia. Incubation with some other galactose-containing glycolipids results in a parallel decrease in binding to oligodendroglia and reduction in antigalactocerebroside antibody titer. Antigalactocerebroside antibodies provide a useful and specific tool with which to study development of oligodendroglia and myelin as well as immunopathologic mechanisms which might be involved in demyelinating diseases.