The pathogenetic significance of cross reactions in autoimmune disease of the nervous system

Susceptibility to murine hepatitis virus (type 3)-induced paralysis is influenced by class I genes of the MHC

Using H-2 recombinant congenic strains of mice, genetic analysis of resistance to murine hepatitis virus type 3 (MHV3)-induced paralysis was performed. It appeared that both H-2K and H-2D, two class I gene regions of the mouse major histocompatibility complex (MHC), can play independent significant roles in the establishment of such resistance.

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. III. Failure of neuroantigen-specific immune tolerance to affect the clinical course of demyelination

Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) into susceptible mouse strains produces a chronic demyelinating disease in which mononuclear cell-rich infiltrates in the central nervous system (CNS) are prominent. Current evidence strongly supports an immune-mediated basis for myelin breakdown, with an effector role proposed for TMEV-specific, major histocompatibility complex (MHC) class II-restricted delayed-type hypersensitivity (DTH) responses in which lymphokine-activated macrophages mediate bystander demyelination. The present study examined the possibility that concomitant or later-appearing neuroantigen-specific autoimmune T cell responses, such as those demonstrated in chronic-relapsing experimental allergic encephalomyelitis (R-EAE), may contribute to the demyelinating process following TMEV infection. T cell responses against intact, purified major myelin proteins (myelin basic protein (MBP) and proteolipid protein (PLP], and against altered myelin constituents were readily demonstrable in SJL/J mice with R-EAE, but were not detectable in SJL/J mice with TMEV-induced demyelinating disease. TMEV-infected mice also did not display T cell responses against the peptide fragments of MBP(91-104) and PLP(139-151) recently shown to be encephalitogenic in SJL/J mice. In addition, induction of neuroantigen-specific tolerance to a heterogeneous mixture of CNS antigens, via the i.v. injection of syngeneic SJL/J splenocytes covalently coupled with mouse spinal cord homogenate, resulted in significant suppression of clinical and histologic signs of R-EAE and the accompanying MBP- and PLP-specific DTH responses. In contrast, neuroantigen-specific tolerance failed to alter the development of clinical and histologic signs of TMEV-induced demyelinating disease or the accompanying virus-specific DTH and humoral immune responses. These findings demonstrate that TMEV-induced demyelinating disease can occur in the apparent absence of neuroantigen-specific autoimmune responses. The relationship of the present results to the immunopathology of multiple sclerosis is discussed.

Lack of cross-reaction between myelin basic proteins and putative demyelinating virus envelope proteins

No cross-reaction could be detected between purified myelin basic proteins (MBP) from mouse, rat or human origins and envelope proteins of viruses suspected of inducing demyelinating processes. In the experimental model using Theiler's murine encephalomyelitis virus, competition radioimmunoassay failed to detect any cross-reaction between MBP and VP1, VP2 and VP3 envelope antigens. In the human situation, antibodies against SV5 and measles viruses, both etiologically linked with multiple sclerosis, also failed to recognize MBP. These results rule out molecular mimicry as a cause of demyelination.

The spectrum of peripheral neuropathy associated with ARC and AIDS

Peripheral neuropathy is increasingly recognized as a complication of the Acquired Immune Deficiency Syndrome (AIDS) and AIDS-related complex (ARC), but the varied clinical features have been incompletely described. Thirty homosexual men with peripheral neuropathy were evaluated in this study. Twenty-one had ARC and nine had AIDS. Four distinct clinical syndromes were recognized: distal sensorimotor polyneuropathy, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), mononeuropathy multiplex, and progressive polyradiculopathy. Four patients with clinical, electrophysiologic, and histologic evidence of CIDP and severe progressive weakness improved with plasma exchange, three regaining normal function.

Antibody-mediated peripheral neuropathies associated with ARC and AIDS: successful treatment with plasmapheresis

Peripheral neuropathy is increasingly recognized in patients with AIDS as well as AIDS-related complex (ARC). Thirty homosexual men with polyneuropathy were evaluated in this study. Twenty-one had ARC and nine had AIDS. We observed three distinct clinical syndromes: distal sensorimotor polyneuropathy, chronic inflammatory demyelinating polyrediculoneuropathy (CIDP), and mononeuropathy multiplex. Circulating antibodies to peripheral nerve tissues were found in all patients. In six patients, treatment with plasma exchange was undertaken because of severe, progressive weakness. Four patients with clinical, electrophysiologic, and histologic evidence of CIDP improved with plasma exchange, three regaining normal function. These results suggest that the peripheral neuropathy associated with ARC and AIDS is immunologically mediated and that plasma exchange is an effective treatment in a subgroup of patients with this disorder.

Plasmapheresis in the treatment of acute relapsing inflammatory demyelinating polyradiculoneuropathy associated with human immunodeficiency virus infection: a case report

Neurologic complications, including both the acute and chronic forms of inflammatory demyelinating polyradiculoneuropathy (IDP) are becoming more prevalent among patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related-complex (ARC). Although the etiology of the above radiculoneuropathies is not known, an autoimmune process has been postulated. Plasmapheresis has been reported to be of benefit in both the acute and chronic forms of these neuropathies. In this report we describe the use of plasmapheresis in the treatment of a patient with ARC and the acute relapsing form of IDP. The treatment consisted of an intensive course of plasmapheresis following his initial presentation and after an acute relapse which occurred several weeks after his initial presentation. Both the initial presentation and relapse involved respiratory compromise necessitating intubation and mechanical ventilation. In both instances marked clinical improvement was achieved after initiation of plasmapheresis. Thus, plasmapheresis may have a role in the management of acute relapsing IDP associated with human immunodeficiency virus infection.

Comparative binding of murine and human monoclonal antibodies reacting with myelin-associated glycoprotein to myelin and human lymphocytes

Human monoclonal IgM antibodies present in the blood of some patients with peripheral neuropathy and murine hybrid IgM antibodies C5 and C6, raised against myelin-associated glycoprotein, and HNK-1, raised against the human T cell line HSB-2, all bind to the carbohydrate moiety of myelin-associated glycoprotein. The relative avidity of the monoclonal antibodies was HNK-1 greater than C5/C6 much greater than human IgM, as determined in a competitive binding radioimmunoassay. HNK-1 bound myelin equally well at incubation temperatures between 4 degrees C and 37 degrees C; the human antibodies bound significantly only at 4 degrees C; and C6 bound best at 4 degrees C, less strongly at 20 degrees C and did not bind at 37 degrees C. All of the antibodies bound to a band corresponding to myelin-associated glycoprotein on immunoblots of human CNS myelin proteins in addition to several other antigens. Flow cytometric studies revealed that the murine but not the human antibodies bind to peripheral blood lymphocytes. Taken together, these data suggest that the antibodies probably recognize the same epitope but bind with different avidity.

The Theiler's murine encephalomyelitis virus (TMEV) model for multiple sclerosis shows a strong influence of the murine equivalents of HLA-A, B, and C

Following intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV), susceptible mouse strains develop a chronic demyelinating disease characterized histologically by mononuclear cell-rich infiltrates in the central nervous system (CNS). An immune-mediated basis for this disease is strongly supported by previous studies demonstrating a correlation between clinical disease susceptibility, the presence of particular H-2 region genotypes, and the development of chronically elevated levels of TMEV-specific, MHC class II-restricted delayed-type hypersensitivity (DTH). The present study compared disease susceptibility in (B10.S X SJL)F1 and (B10.S(26R) X SJL)F1 mice which differ only at the D region of the H-2 complex. The data conclusively demonstrates a major influence for homozygosity of H-2s alleles at the H-2D region (the murine equivalent of the human class I HLA-A, B, and C genes) in determining disease susceptibility, as measured by either clinical or histopathological endpoints. In addition, disease susceptibility strongly correlated with the development of high levels of TMEV-specific DTH in the susceptible (B10.S X SJL)F1 strain. However, disease susceptibility did not appear to correlate with TMEV titers in the CNS, TMEV-specific humoral (ELISA and neutralizing) immune responses, or virus-specific splenic T cell proliferative responses. These findings lend additional support to our hypothesis that CNS myelin damage is mediated by a TMEV-specific DTH response. The possible role of class I-restricted responses in the demyelinating process is discussed and murine TMEV-induced demyelinating disease is compared with experimental allergic encephalomyelitis as relevant animal models for human multiple sclerosis.

Multiple sclerosis: neuroimmunologic puzzle

Multiple sclerosis (MS), a chronic disease with a relapsing and remitting course, is the most common neuroimmunologic condition in the United States. The hallmarks of the disease are focal demyelination and inflammation within the central nervous system (CNS). Because histopathologic changes can be identified only at autopsy, attention has been directed at formulating standardized clinical and laboratory procedures to aid in MS diagnosis. Currently, there are no MS-specific clinical or laboratory tests, but detection of abnormality in cerebrospinal fluid (CSF) IgG is important in supporting clinical evidence of disease. A number of other immunologic abnormalities have been recognized in MS, including the presence of T- and B-lymphocytes within the CNS and alterations in circulating suppressor T-lymphocytes. These findings have been interpreted as indicating disturbed immunoregulation associated with a chronic autoimmune response within the CNS. Evidence implicates viral infection in the pathogenesis of MS but the cause of the disease remains unknown.