Experimental allergic neuritis induced by galactocerebroside

Experimental allergic neuritis (EAN), an animal model of human demyelinative neuritis, was induced by sensitization with galactocerebroside, a glycolipid hapten common in central and peripheral nervous system myelin. Between two months and one year after the initial sensitization, 11 of 24 rabbits immunized repeatedly with bovine brain galactocerebroside (GC) in complete Freund's adjuvant developed a neurological disorder manifested by flaccid quadriparesis, limb hypesthesia, and respiratory paralysis. Seventeen of 20 autopsied rabbits, including all those with clinical illness, had small multiple perivascular foci of demyelinative lesions in roots, dorsal root ganglia, proximal peripheral nerves adjacent to ganglia, and, less frequently, in distal nerves. No change was found in the central nervous system. Demyelination started around venules, with splitting and vesiculation of the outer myelin sheaths of adjacent fibers, and later progressed to form confluent lesions. The lesions were associated with infiltration of phagocytic mononuclear cells, mostly macrophages, which insinuated themselves between myelin lamellae, phagocytized myelin, and subsequently denuded axons. Perivenular infiltration of small lymphocytes, comparable to that seen in whole nerve- induced EAN, was not encountered. The distribution of demyelinative lesions seems to correspond to areas known to have a defective blood-nerve barrier.

A new assay for lytic anti-galactocerebroside (GC) antibodies employing 56Rubidium release from GC-labelled liposomes

This assay is a quick and sensitive method for determination of antibodies to galactocerebroside (GC). The use of antibody-plus-complement radioisotope release from GC-bearing liposomes allows numerous samples to be handled in semi-automated fashion. By substituting alternative gangliosides or cerebrosides, the technique may be simply modified for assay of antibodies to other substances.

EAE, EAN and galactocerebroside sera bind to oligodendrocytes and Schwann cells

Sera from rabbits with EAN induced by sensitization with galactocerebroside (GalC-EAN) bound to the surface of Schwann cells and oligodendrocytes in rat nervous system dispersion cultures. Sera from rabbits with bovine femoral nerve-induced EAN (FN-EAN) bound to Schwann cells, oligodendroglia and occasional fibroblasts. Sera from animals with bovine spinal cord-induced EAE (SC-EAE) bound to these cells and to some astrocytes as well. Absorption of the capacity to bind to oligodendroglia and Schwann cells suggests that GalC is the major, if not the only surface antigen on these two cell types to which these sera bind. The capacity of GalC-EAN, SC-EAE, and FN-EAN sera to bind to the surface of the cells responsible for myelin synthesis in both PNS and CNS correlates with the ability of these sera to cause both PNS and CNS demyelination in vitro and PNS demyelination in vivo.

Antiserum-mediated demyelination: relationship between remyelination and functional recovery

A focal demyelinative lesion of peripheral nerve was produced by intraneural injection of either antiserum from rabbits with experimental allergic neuritis or experimental allergic encephalomyelitis or antiserum to galactocerebroside. We studied the relationship between clinical and electrophysiological recovery from this lesion and the morphological pattern of remyelination. Foot muscles on the the injected side weakened within an hour of injection and remained paralyzed for 7 days; strength gradually returned to normal by 16 days after injection. Electrophysiological conduction block, apparent within a few hours of injection, persisted for about 7 days. At 8 days we detected dispersed, very low amplitude muscle action potentials with long latency. Morphologically, demyelinated axons were surrounded by Schwann cells at 7 days after injection, but compacted myelin was not present. After 8 days, remyelinating axons became surrounded by thickening compacted myelin. The time of onset of remyelination and the rate of remyelination up to 14 days following the injection were independent of axon size. The onset of clinical and electrophysiological recovery from the lesion corresponded to the appearance of 2 to 8 myelin lamellae around each remyelinating axon. At 37 days after injection, when conduction velocities had returned to preinjection values, myelin thickness of remyelinating fibers had increased to approximately one-third that of control nerves.

Demyelination produced by experimental allergic neuritis serum and anti-galactocerebroside antiserum in CNS cultures. An ultrastructural study

Cultures of mouse cerebellum were exposed to sera from rabbits with experimental allergic neuritis induced by whole peripheral nerve immunization (WN-EAN) and to rabbit anti-galactocerebroside (GC) antisera, and were studied by electron microscopy. Both antisera produced almost identical demyelinative patterns. These consisted of large intramyelinic splittings, "smudged" changes of myelin, degeneration of oligodendrocytes, and phagocytosis of myelin by astrocytes, changes similar to those described after application of whole spinal cord-induced experimental allergic encephalomyelitis (WM-EAE) sera. In addition, patterns which have been considered more characteristic of in vivo demyelinative lesions have been found, susch as vesicular disruption of myelin lamellae and peeling off and phagocytosis of myelin by phagocytic mononuclear cells with electron dense cytoplasm. The morphologic similarities between demyelinative patterns in central nervous system (CNS) cultures induced by anti-GC antiserum and WN-EAN serum and WM-EAE serum, and the fact that elevated antibody titers to GC are found in sera from rabbits with WN-EAN and WM-EAE (Saida, et al., 1977), support the concept that anti-GC antibody is the major factor in the production of CNS demyelination in vitro by sera from rabbits with WN-EAN and WN-EAE.

Peripheral nerve demyelination induced by intraneural injection of experimental allergic encephalomyelitis serum

Intraneural injection of sera from rabbits with experimental allergic encephalomyelitis, induced by sensitization with bovine brain white matter in complete Freund's adjuvant, produced focal primary demyelinative lesions in rat sciatic nerves. Demyelinating activity was removed by prior incubation of antisera with central (CNS) and peripheral nervous system (PNS) myelin but not with liver or kidney, and was heat-labile and complement-dependent. Recipient animals developed a sensorimotor disturbance of their toes and ankles on the side injected with antiserum. Twenty minutes after antiserum injection, Schwann cells showed focal cytoplasmic outpouching and their external mesaxons opened. Between 1 and 8 hours after injection vacuolation, splitting and vesiculation of myelin became increasingly prominent at Schmidt-Lanterman clefts and paranodal regions, with concomitant degenerative changes in Schwann cell cytoplasm. Polymorphonuclear cell infiltration and endoneurial edema were apparent at this time. Substantial demyelination occurred before the appearance of phagocytic cells. Between 8 hours and 3 days many nerve fibers were surrounded and attacked by invading macrophages. Axons became demyelinated progressively over several internodes by macrophage phagocytosis. Early signs of remyelination were observed by 5 days. These findings suggest that antibodies directed against antigens common to both CNS and PNS myelin can produce in vivo peripheral nerve demyelination.

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.

In vivo demyelination induced by intraneural injection of anti-galactocerebroside serum: a morphologic study

Intraneural injection of rabbit anti-galactocerebroside (anti-GC) serum produced focaldemyelinative lesions in rat sciatic nerves. Recipient rats developed a sensory motordeficit of the toes and feet on the side injected with anti-GC serum. Schwann cellabnormalities in recipient nerves were apparent by 20 minutes, followed by myelinsplitting and vesiculation over the next 8 hours. Macrophages first appeared in moder-ate numbers by 15 hours, and degraded myelin was completely phagocvtized by 5 days.An acute inflammatory reaction consisting of endoneurial edema, polymorphonuclearcell infiltration, and fibrin extravasation also was prominent. In vivo demyelinativeactivity of rabbit anti-GC serums was removed by pre-incubation with GC or central orperipheral nervous system myelin and was also lost when the serums were heated at 56C for 30 minutes and injected into nerves of rats previously injected with cobra venomfactor. Anti-GC antibodies are present in the serum of rabbits with experimentalallergic neuritis (WNV-EAN) and encephalomyelitis (WM-EAE) produced, respectively,by immunization with whole peripheral nerve or brain white matter and may play arole in the pathogenesis of demyelination in GC-induced EAN, WN-EAN, or WM-EAE.

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.

Antiserum-mediated demyelination in vivo: a sequential study using intraneural injection of experimental allergic neuritis serum

Primary segmental demyelination accompanied by mononuclear phagocytes was induced by injection of antiserum into rat peripheral nerve, and the morphologic sequence of events was studied. Antisera were obtained from rabbits with experimental allergic neuritis (EAN) produced by the inoculation of emulsified bovine peripheral nerves in complete Freund's adjuvant. Sera were injected directly into rat sciatic nerve to circumvent the blood-nerve barrier. Recipient rats developed sensorimotor paralysis on the side injected with experimental allergic neuritis sera. Intense focal demyelinative lesions resulted from injection of experimental allergic neuritis sera. Control sera obtained from rabbits inoculated with bovine serum albumin in complete Freund's adjuvant did not produce paralysis or demyelination. The earliest change was damage to Schwann cells, seen 20 minutes after antiserum injection. Within a few hours lamellar splitting and vacuolation of myelin began to paranodal regions and Schmidt-Lanterman clefts and there were infiltrating polymorphonuclear cells. By 8 hours without the detectable presence of monocytes or macrophages, myelin vesiculation became advanced and widespread. By 15 hours, endoneurial edema had reached its maximum. Macrophages were found in association with myelinated nerve fibers. From that time through the next 5 days, demyelination progressed to complete denudation of axons by macrophage phagocytosis of myelin. Activated cytoplasm of Schwann cells reinvested demyelinated axons, often in concert with persisting phagocytic macrophages. Peripheral nerve demyelination thus transferred evolved rapidly, and myelin destruction occurred prior to the appearance of monocytes or macrophages. Demyelinating activity was lost after absorption by purified peripheral nerve myelin but not by liver or kidney and was heat-labile and complement dependent (T. Saida, K. Saida, D. H. Silberberg, and M. J. Brown: Nature 272: 639, 1978).