Suppression of experimental allergic neuritis in rats by prior immunization with nerve in saline

The antibody repertoire in experimental allergic neuritis: evidence for PMP-22 as a novel neuritogen

Experimental allergic neuritis (EAN) is an autoimmune disease that serves as an animal model for the Guillain-Barré syndrome (GBS). In both disorders there is still great uncertainty as to the significance and diversity of autoantibodies involved. We focused on the characterization of serum antibody production in response to various peripheral nervous system (PNS) myelin proteins during the course of actively induced EAN in Lewis rats. These data were compared with EAN induced by adoptive transfer of P2-specific CD4+ T cells (AT-EAN) and with inoculation with complete Freund's adjuvant (CFA) alone. Semiquantitative Western blotting was applied to measure serum IgM and IgG titers against specific myelin proteins, including P2, P0, myelin basic protein (MBP), myelin-associated glycoprotein (MAG) and PMP-22. Considerable differences in the dynamics of antibody titers against individual myelin proteins were observed in active EAN and after inoculation with CFA alone. Our data suggest a pathogenic role of IgM antibodies against HNK adhesion carbohydrate epitope expressing PNS proteins P0, MAG and PMP-22. Among these, PMP-22, a novel candidate neuritogen may be of particular relevance. Thus, we provide evidence for the involvement of antibody-mediated immune response in actively induced EAN and a basis for similar studies on related human disorders such as GBS or other demyelinating neuropathies.

Effects of glucocorticoids on experimental allergic neuritis

Corticosteroids were administered to rats and guinea pigs with experimental allergic neuritis, from the time of inoculation with antigen or from the onset of signs of disease. No statistically significant effects were observed in guinea pigs. In rats, to which large doses of corticosteroids were administered, disease severity was slightly but significantly reduced in both groups and recovery was more rapid in the animals treated from the time of induction of disease. These results were comparable with those obtained in trials of corticosteroids in acute inflammatory polyneuropathy in man, which have also not demonstrated any striking effects.

Attempts to suppress experimental allergic neuritis in the rat by pretreatment with antigen

The injection of bovine dorsal root antigen in complete Freund's adjuvant can be used to produce experimental allergic neuritis (EAN) in rats. In this study attempts were made to prevent the development of the disease by prior injections of antigen. It was found that eight intradermal (i.d.) injections of antigen in either incomplete Freund's adjuvant or in saline failed to suppress EAN. A single intraperitoneal (i.p.) injection of antigen in saline produced only minimal protection against the disease. However, it was found that rats which had been given a primary course of EAN were subsequently completely unresponsive to a second injection of antigen.

Studies with antisera against peripheral nervous system myelin and myelin basic proteins. I. Effects of antiserum upon living cultures of nervous tissue

We studied the effects of antiserum against rat peripheral nervous system (PNS) myelin, rat or chicken central nervous system myelin basic protein (BP), or rabbit P2 protein from PNS myelin on myelinated cultures containing only rat dorsal root ganglion neurons and Schwann cells. While anti-PNS myelin serum consistently produced segmental PNS demyelination, anti-BP serum and anti-P2 serum did not. The culture results suggest that the myelin PNS proteins P1 (identical to basic protein from central nervous system myelin) and P2 are not exposed on the extracellular surfaces of myelin-related Schwann cells in tissue culture.

Cell-mediated immunity in idiopathic polyneuritis

The role of cell-mediated immunity (CMI) in the pathogenesis of idiopathic polyneuritis (IP) is discussed. Of significance has been the finding of a decreased suppressor T cell response in IP. This may provide an important common denominator linking the numerous antecedent events which trigger IP to the disease. The role of humoral immunity in IP and chronic relapsing inflammatory polyneuritis (CRIP) remains controversial, but has awakened renewed interest in view of recent reports of favorable response to plasmapheresis in IP and CRIP patients. P2 protein is an important neuritogenic factor in experimental allergic neuritis (EAN), but we failed to find antibody directed against P2 in either IP or CRIP even though anti-P2 antibody was regularly detected in EAN. Whether CMI response to P2 occurs in IP or CRIP remains controversial. We did not detect CMI response to P2 in IP or CRIP. It may be that the neuritogenic factor (or factors) in IP and CRIP remains to be found.

Experimental allergic neuritis. I. Rat strain differences in the response to bovine myelin antigens

Strain differences among rats to the induction and severity of experimental allergic neuritis (EAN) in response to whole PNS myelin were observed. Lewis rats were highly susceptible and developed severe EAN without central nervous system lesions (EAE), while Brown Norway rats were most resistant. Wistar, Sprague-Dawley, and Buffalo rats were susceptible but developed less severe disease than Lewis rats. Only Lewis rats consistantly developed EAN in response to isolated P2 protein. The severity of EAN was enhanced by treatment of the P2 with mercaptoethanol prior to injection. None of the strains developed EAN in response to galactocerebroside and none developed the lesions of EAE in response to any of the bovine myelin antigens tested. Myelin protein profiles from these rat strains were similar which suggests that factors other than target tissue differences, such as genetically determined immune responses to bovine myelin antigens, must be involved in these differing responses.

Demyelination in allergic and Marek's disease virus induced neuritis. Comparative electron microscopic studies

Patterns of demyelination were studied in sciatic nerves, spinal roots and ganglia of chickens afflicted with either Marek's disease (MD) or experimental allergic neuritis (EAN). MD was induced in susceptible chicks after hatching by inoculation of the JM strain of MD Herpes virus. Tissues from these chickens were examined 7-83 days after infection. EAN was studied 10-21 days after sensitization of 4 week old chickens to emulsions containing human peripheral nerve with complete Freund's adjuvant. In both conditions lesions were encountered which consisted of perivenular infiltrates of mononuclear cells that penetrated the basal lamina of the neurolemmal sheath, displaced Schwann cells, lysed and stripped myelin lamellae without damage to axons. Other lesions in MD were characterized by lymphomatous infiltrates that contained necrotic cells and disintegrating axons. The similarity of the demyelinating process in MD to that seen in EAN suggests that MD virus infection activates lymphocytes sensitized to peripheral nerve myelin. The findings are discussed with reference to acute idiopathic polyneuritis (Guillain-Barré syndrome) in patients with preceding or concurrent Herpes virus infections including those known to cause lymphoproliferative disorders.

Recurrent experimental allergic neuritis. An electron microscope study

Experimental allergic neuritis has been induced in 52 guinea pigs by the inoculation of rabbit peripheral nerve in Freund's adjuvant. The majority of the animals developed an acute monophasic illness after a mean interval of 16 days and, if they survived, recovered fully after an average period of 52 days. Two animals displayed a more chronic course and 1 animal relapsed spontaneously after clinical recovery had occurred. Twenty-three animals that recovered were re-inoculated when recovery was complete and in 4 a relapse was induced. In the remainder, no clinical response was observed, even after repeated reinoculations. The ultrastructural appearances in the animals with a monophasic illness were similar to those previously reported. The appearances differed markedly in those animals that were induced to relapse and were similar to those in the animal that relapsed spontaneously. The findings indicated persistent demyelination and remyelination with striking hypertrophic changes (onion bulb neuropathy). The possible reasons for the differences between the two groups are discussed.