Retrovirus mediated gene transfer of the self antigen MBP into the bone marrow of mice alters resistance to experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is a prototypic model of organ specific autoimmunity. MHC class II restricted T-cells directed against myelin basic protein (MBP) have been shown to cause EAE in susceptible strains of mice. We have asked whether the introduction of a gene encoding an autoantigen (MBP) into the hematopoetic stem cells of mice would result in tolerance to that protein. We have introduced cDNA encoding the 21.5 kDa isoform of MBP into the hematopoetic stem cells of B10.PL (73NS), SJL, and B10 mice by retrovirus-mediated gene transfer. Our experiments show expression of proviral MBP in peripheral blood and thymus following transplantation of genetically modified stem cells. Such expression does not result in deletion of MBP-specific T cells or tolerance to MBP, nor does it alter susceptibility to MBP-induced EAE in susceptible strains B10.PL and SJL. However, retrovirus-mediated gene transfer resulted in resistant B10 mice developing mild EAE. This report demonstrates that autoreactive MBP-specific T cells can be selected in the presence of endogenous antigen or an MBP-encoding retrovirus.

Superantigen modulation of experimental allergic encephalomyelitis: activation of anergy determines outcome.

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease that can be induced by the adoptive transfer of CD4, myelin basic protein (MBP)-specific T cells. Superantigens activate T cells expressing appropriate TCR V genes. In this study, MBP-specific T cells activated in vitro with a superantigen, staphylococcal enterotoxin B (SEB), could adoptively transfer a severe form of EAE in (PLxSJL)F1 mice, but did not transfer disease in PL/J or SJL/J mice. SEB treatment of donor mice anergized MBP-specific T cells using V beta 8 in (PLxSJL)F1 mice, because subsequent in vitro activation with SEB resulted in a marked decrease in proliferation to SEB and inability to transfer EAE. However, donor cells from (PLxSJL)F1 mice immunized with MBP/CFA that had been exposed to SEB in vivo before MBP stimulation in vitro still produced EAE in recipient mice. To confirm that non-V beta 8 T cells could transfer disease, donor mice were treated with antibody that eliminated V beta 8 T cells; MBP-activated T cells from these mice could still transfer EAE. Finally, EAE induced by SEB-activated T cells was substantially reduced in mice receiving anti-V beta 8 therapy in vivo. The ability of superantigens to activate encephalitogenic T cells may have relevance to human diseases such as multiple sclerosis.

Demonstration of human T-cell lymphotropic virus type I (HTLV-I) from an HTLV-I seronegative south Indian patient with chronic, progressive spastic paraparesis.

Here we describe a human T-cell lymphotropic virus type I (HTLV-I) seronegative patient from South India with a chronic, progressive spastic paraparesis from which HTLV-I has been isolated from peripheral blood lymphocytes. HTLV-I pol and tax viral sequences were detected in DNA from fresh peripheral blood lymphocytes (PBL) by polymerase chain reaction (PCR) and liquid hybridization techniques. Southern blot analysis of the PCR products demonstrated a low copy number of HTLV-I at the level of one viral copy per 10,000 fresh PBL. A long-term CD4+ T-cell line was established from PBL of this patient using recombinant interleukin-2, OKT3, and feeder cells. DNA from these cultured lines was amplified and portions of the HTLV-I long terminal repeat (U3), pol, env, and tax regions were sequenced (a total of 1,115 bp). The sequence data showed that the HTLV-I associated with this patient was 98.8% homologous to prototype HTLV-I. Southern blot analysis also confirmed the presence of full-length HTLV-I. These results indicate that HTLV-I can be demonstrated in an HTLV-I seronegative patient from South India with a chronic progressive neurological disorder.

Sequence comparisons of HTLV-I from HAM/TSP patients and their asymptomatic spouses.

We amplified and sequenced portions of the human T-lymphotropic virus type I (HTLV-I) (U3), pol, env, and pX provirus regions (1212 bp per person) from peripheral blood lymphocytes (PBL) of two married couples (case 1 and case 2). Both husbands are patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and the wives are asymptomatic HTLV-I carriers. We selected these regions because the LTR and env regions of murine retrovirus models have been involved in determining tissue tropism. In addition, the predominant immunogenic epitope for HTLV-I-specific cytotoxic T cells obtained from circulating PBL of HAM/TSP patients was localized in the HTLV-I pX region. Our aim was to examine variations in these HTLV-I regions between affected and asymptomatic spouses. In the HTLV-I regions studied, we detected no sequence variation between each couple. These data do not favor the hypothesis that neurotropic mutants of HTLV-I are involved in the pathogenesis of HAM/TSP.

Correlation between magnetic resonance imaging findings and lesion development in chronic, active multiple sclerosis.

Magnetic resonance imaging is a highly sensitive method for the detection of the lesions of multiple sclerosis and renders possible the study and the evolution of early lesions. Previous reports on magnetic resonance imaging following gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) injection demonstrated that new lesions can be recognized by contrast enhancement. The pathological basis of these observations is uncertain. We have had the opportunity to study at autopsy the brain of a patient with chronic progressive multiple sclerosis who suffered acute worsening leading to death. Magnetic resonance imaging performed 10 days and 4 weeks prior to death showed new Gd-DTPA-enhanced lesions in the posterior hemispheric white matter adjacent to the lateral ventricles. Light microscopic examination of these areas demonstrated them to be fresh lesions comprising intense inflammatory activity and dense perivascular cuffs within an edematous lesion center and a striking parenchymal mononuclear cell infiltration at the margins of the lesions. Lesions that were demonstrated by increased signal on T2-weighted images, but were not enhanced following administration of Gd-DTPA, were all of the chronic type, either inactive or active. None of these showed the intense inflammatory activity of the acute lesions and most displayed fibrous astrogliosis.

Differential effect of interleukin-1 beta on Ia expression in astrocytes and microglia.

In an earlier study we demonstrated the inhibitory effect of interleukin-1 beta (IL-1 beta) on human leukocyte antigens (HLA) class II enhancement by interferon-gamma (IFN-gamma) in a human glioblastoma multiforme cell line. In this study we have examined the effect of IL-1 beta on IFN-gamma induced major histocompatibility complex (MHC) class II (Ia) in primary cultures of newborn murine astrocytes and microglial cells. Astrocytes expressed very low levels of Ia molecules under basal culture conditions but these molecules could be induced with IFN-gamma. IL-1 beta in doses ranging from 1 to 100 units/ml inhibited the level of IFN-gamma induced Ia expression on astrocytes, and this inhibition was dose-dependent (mean maximum inhibition of 53 +/- 5% in number of positive cells and 53 +/- 2.6% in mean fluorescence intensity in four separate experiments). IL-1 beta treatment had no effect on MHC class I induction by IFN-gamma in the astrocytes. In contrast, microglial cells expressed Ia molecules under basal culture conditions, and this expression was enhanced by IFN-gamma treatment. Both basal and IFN-gamma induced Ia expression on microglia were resistant to IL-1 beta treatment in doses ranging from 1 to 100 units/ml. These results indicate that Ia expression is differentially regulated on astrocytes and microglial cells and that IL-1 beta may have an important immune regulatory function in the central nervous system.

Systemic histiocytosis presenting as multiple sclerosis.

A patient resembling one with progressive multiple sclerosis in clinical presentation and by magnetic resonance imaging was studied in detail. Some features atypical for multiple sclerosis prompted a persistent search for an alternative cause. The diagnosis of a non-Langerhans systemic histiocytosis involving brain and bone was established and showed a partial response to radiation therapy. This patient illustrates the continued importance of a broad approach to the evaluation of possible multiple sclerosis, with particular attention to atypical features.

Isolation of HTLV-II from a patient with chronic, progressive neurological disease clinically indistinguishable from HTLV-I-associated myelopathy/tropical spastic paraparesis.

An increasing spectrum of diseases has been shown to be associated with the human T-cell lymphotropic virus type I (HTLV-I), most notably a chronic, progressive myelopathy termed HTLV-I--associated myelopathy/tropical spastic paraparesis and adult T-cell leukemia. HTLV-II is a close relative of HTLV-I and is structurally similar but molecularly distinct. This virus is endemic in Amerindian populations and a high seroprevalence rate has been observed in intravenous drug abusers. Here, for the first time, we have identified a patient with a chronic, progressive neurological disease clinically indistinguishable from HTLV-I--associated myelopathy/tropical spastic paraparesis from whom we have isolated and characterized HTLV-II in the absence of any other detectable human retrovirus. Antibodies to HTLV were detected in both serum and cerebrospinal fluid, with typical HTLV-II banding patterns on Western blots. HTLV-II viral sequences were detected in high copy number from peripheral lymphocytes by polymerase chain reaction techniques, and cloning and sequencing of this virus revealed a 99.5% homology with prototype HTLV-II. These results serve to alert the medical community to the possibility that in addition to HTLV-I, HTLV-II may be associated with a neurological disorder.

Regulation of MHC class I and beta 2-microglobulin gene expression in human neuronal cells. Factor binding to conserved cis-acting regulatory sequences correlates with expression of the genes.

MHC class I molecules are coexpressed with beta 2-microglobulin (beta 2-M) on many somatic cells. However, these proteins are normally not present on cells of the central nervous system (CNS). Cells derived from human neuroblastomas were used as a model for investigating the molecular basis for the paucity of MHC class I and beta 2-M gene expression in neural cells and for the induction of these genes by two cytokines, IFN-gamma, and TNF-alpha. These cytokines independently increased MHC class I and beta 2-M cell surface expression on the neuroblastoma cell lines. IFN-gamma or TNF-alpha also increased MHC class I and beta 2-M steady-state RNA levels and the expression of MHC class I and beta 2-M CAT reporter constructs transiently transfected into the neuroblastoma cell lines, indicating that the cytokines acted by increasing the transcription of these genes. MHC class I and beta 2-M genes share two conserved regulatory elements, an NF kappa B-like site and the IFN consensus sequence, that act as a constitutive enhancer and an IFN-responsive element, respectively. Low MHC class I and beta 2-M gene expression in these cells was accounted for by undetectable to low factor binding activity specific for the above regulatory elements of these genes. TNF-alpha increased factor binding activity specific for the NF kappa B-like elements and IFN-gamma increased factor binding activity specific for the IFN consensus sequence elements of the MHC class I and beta 2-M genes, but not vice versa. Taken together, our results indicated that IFN-gamma and TNF-alpha increased MHC class I and beta 2-M gene expression in the neuroblastoma cell lines by inducing factor binding to the regulatory elements present in both genes.

Cytokine-regulated adhesion between encephalitogenic T lymphocytes and cerebrovascular endothelial cells.

Adhesive interactions between murine cerebrovascular endothelial cells (EC) which comprise the blood-brain barrier (BBB) and myelin basic protein (MBP)-specific encephalitogenic T lymphocytes were investigated. Adhesion was assessed by measuring the percent attachment of 51Cr-labeled T cells to EC monolayers. The basal level adhesion (20-35%) was significantly up-regulated by treating EC with recombinant murine gamma interferon (IFN-gamma), interleukin-1 alpha (IL-1 alpha) and/or tumor necrosis factor-alpha (TNF alpha). The ability of these cytokines to modulate adhesion was dose- and time-dependent and could be detected as early as 1 h after treatment. The expression of intercellular adhesion molecule-1 (ICAM-1) by EC was examined by immunofluorescence staining and ELISA. Although all unstimulated EC cultures expressed ICAM-1, treatment of EC with the above cytokines dramatically up-regulated the level of ICAM-1 expression in a dose- and time-dependent fashion similar to that observed in the adhesion assays. Treatment of EC with transforming growth factor-beta 1 (TGF beta) down-regulated the level of T cell adhesion on untreated EC in a dose-dependent manner. Pretreatment of EC with TGF beta also partially inhibited the up-regulation of adhesion induced by IFN-gamma, IL-1 alpha and/or TNF alpha. TGF beta had no effect on the up-regulation of ICAM-1 expression induced by IFN-gamma, IL-1 alpha and/or TNF alpha. These results indicate that in addition to ICAM-1, other molecules may be involved in adhesion of encephalitogenic T cells to the EC comprising the cerebral vasculature.(ABSTRACT TRUNCATED AT 250 WORDS)

T-lymphocyte recognition of a portion of myelin basic protein encoded by an exon expressed during myelination.

The major isoform of myelin basic protein (MBP) in the healthy adult central nervous system is the 18.5-kDa protein which is produced by mRNA derived from exons 1, 3, 4, 5, 6 and 7 of the MBP gene. Since isoforms containing exon 2-encoded protein (X2MBP) are expressed during myelin formation, we examined T cell reactivity specific for X2MBP in a disease characterized by remyelination subsequent to demyelination, multiple sclerosis (MS). T cell lines specific for X2MBP were derived from three MS patients as well as one healthy control. This suggests that candidate autoantigens in demyelinating/remyelinating diseases should include not only the major isoforms of myelin proteins, but also isoforms expressed aberrantly during a disease process since they too may be the target of a T cell-mediated autoimmune process.

Transthyretin Pro55, a variant associated with early-onset, aggressive, diffuse amyloidosis with cardiac and neurologic involvement.

Mutations in the protein transthyretin cause amyloidosis involving the heart, peripheral nerves, and other organs. A family from West Virginia developed an unusually aggressive form of widespread transthyretin amyloidosis. Single-strand conformation polymorphism analysis revealed a variant in the transthyretin gene, which was found on sequencing to be a T----C transversion at position 2 of codon 55, corresponding to a Leu----Pro substitution. The variant sequence was confirmed by restriction analysis and polymerase chain reaction (PCR)-primer introduced restriction analysis.

Evidence of endogenous regulatory function of transforming growth factor-beta 1 in experimental allergic encephalomyelitis.

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease characterized by inflammation and demyelination in the central nervous system (CNS). Administration of transforming growth factor-beta (TGF-beta) has been shown to inhibit EAE. In this study, the possible role of endogenous TGF-beta in the regulation of relapsing EAE produced by the transfer of myelin basic protein-specific T cell lines was assessed. Although TGF-beta is not present in the normal CNS, this cytokine was detected by immunohistology in areas of central nervous system inflammation in both acute and chronic disease. The administration of anti-TGF-beta at the disease onset led to a worsening of the clinical course of EAE and more extensive pathological lesions. These findings provide direct evidence for a role of endogenous TGF-beta in the remissions seen in chronic relapsing EAE.

Demyelinating disease after neurologically complicated primary Epstein-Barr virus infection.

This report describes five patients who, following a neurologically complicated primary Epstein-Barr virus infection, developed progressive or relapsing neurologic deficits. The sequelae in four patients followed 4 to 12 years led to the diagnosis of multiple sclerosis (MS). The fifth patient presented with acute disseminated sclerosis and exhibits diffuse neurologic deficits that have persisted for 2 years. We suggest that the diagnosis of an unexplained acute neurologic or psychiatric syndrome should raise the question of a primary EBV etiology. A precisely timed serologic and hematologic study of the blood is imperative to capture the essential evidence. The data presented represent a clinical association between a neurologically complicated primary EBV infection and both chronic and acute demyelinating disease. The evidence does not justify a conclusion that EBV virus causes MS.

Gamma-interferon induction in patients with chronic progressive MS.

Although gamma interferon (gamma-IFN) may be involved in the pathogenesis of exacerbations of multiple sclerosis (MS), whether it plays a role in chronic progressive MS is not known. To investigate this, we retrospectively analyzed serum samples from nine chronic progressive MS patients who were treated with monthly intravenous infusions of the interferon inducer polyinosinic acid polycytidylic acid polylysine in carboxymethylcellulose (poly ICLC). Using a bioassay we found that the mean peak total interferon level was 177 U/ml 12 hours after infusion, and using a radioimmunoassay we found that the mean peak gamma-IFN level was 15.9 U/ml 12 hours after infusion, so that gamma-IFN made up approximately 10% of the total. Greater gamma-IFN induction did not correlate with clinical worsening; induced gamma-IFN levels were not higher in two patients who worsened on treatment, and the highest levels were found in a patient who remained stable. Either chronic progressive MS is not sensitive to gamma-IFN or the effects of gamma-IFN are masked by other mediators induced by poly ICLC.

Cerebral vascular endothelial cells are effective targets for in vitro lysis by encephalitogenic T lymphocytes.

Lysis of cerebral vascular endothelial cells (EC) by CD4-positive, myelin basic protein-specific encephalitogenic T cell lines was investigated. Unstimulated EC were not lysed, but culture in the presence of murine rIFN-gamma resulted in the expression of class II MHC (Ia) molecules and the concomitant ability to function as effective target cells for lysis. The possible requirement for Ia molecules was further demonstrated by antibody-blocking experiments. Lysis of EC targets also required the presence of specific Ag (myelin basic protein); PPD-specific T cell lines also lysed the PPD-pulsed EC. In all cases, lysis was directly proportional to E:T ratios. In addition, continuous passage of T cell lines resulted in the concomitant loss of encephalitogenicity and ability to affect EC lysis, indicating a possible relationship between these two factors. These results demonstrate that CD4+ T cells interact with cerebral vascular EC. It is suggested that such interactions may be important in the pathogenesis of diseases involving migrations of these cells across the blood-brain barrier.

Non-AIDS retroviral infections in humans.

In the decade since the first human retrovirus was identified, one form of leukemia and a chronic neurological disorder have been shown to be related to this agent. A spectrum of lymphomas, additional inflammatory disorders such as polymyositis, and possibly other neurological diseases also have been linked to HTLV-I infection. Although the pathogenesis of these disorders remains to be defined, these exciting developments coupled with the discovery that AIDS is a retroviral-induced disease indicate that human retroviruses are responsible for a variety of human disorders and suggest that other agents such as members of the foamy virus subfamily, as well as yet unidentified human retroviruses, may produce other human diseases.

Changes in leukocyte recirculation, NK cell activity, and HLA-DR expression in peripheral blood mononuclear cells of MS patients treated with Poly ICLC.

To investigate the cellular immune effects of the interferon inducer, Poly ICLC, in humans, peripheral blood mononuclear cells from patients with multiple sclerosis receiving Poly ICLC as part of a preliminary clinical trial were studied. Peripheral blood mononuclear cell phenotype analysis using fluoresceinated monoclonal antibodies and flow microfluorometry showed decreases in the percentages and absolute numbers of all lymphocyte subsets 24 h after infusion. These changes returned toward baseline at 48 h except the percentage of CD-4 positive cell which increased above baseline levels. The percentage of HLA-DR antigen positive cells and CD-16 (Leu 11a) positive cells were increased 24 h after infusion but returned to baseline at 48 h. NK activity as determined by chromium release from K562 target cells was decreased at 24 h but increased 48 h after drug infusion. The increases in percentages of HLA-DR antigen and CD-16 positive cells at 24 h and NK activity at 48 h are consistent with the in vitro effects of IFN while the decreases in peripheral blood mononuclear cells are suggestive of changes in cell recirculation.

Circulating CD8+ cytotoxic T lymphocytes specific for HTLV-I pX in patients with HTLV-I associated neurological disease.

The human T-lymphotropic virus type I (HTLV-I), the first human retrovirus to be characterized, is associated with adult T-cell leukaemia and a chronic progressive disease of the central nervous system termed tropical spastic paraparesis, or HTLV-I-associated myelopathy. Only 1% of individuals infected with HTLV-I develop clinical disease however. The various manifestations of an HTLV-I infection may be related to differences in the genetic backgrounds of individuals, infection with variant strains of HTLV-I, differences in viral tropism or host immune response to the virus. Whereas the humoral response to HTLV-I is well characterized, little is known about the human cellular immune response, such as the production of cytotoxic T lymphocytes. Here we report the presence of high levels of circulating HTLV-I-specific cytotoxic T lymphocytes in patients with HTLV-I associated neurological disease but not in HTLV-I seropositive individuals without neurological involvement. These cytotoxic T lymphocytes are CD8+, HLA class I- restricted and predominantly recognize the HTLV-I gene products encoded in the regulatory region pX. These findings suggest that HTLV-I-specific cytotoxic T lymphocytes may contribute to the pathogenesis of associated neurological disorders associated with HTLV-I.

Alterations in T cell antigen specificity and class II restriction during the course of chronic relapsing experimental allergic encephalomyelitis.

In order to assess T cell antigen specificities and class II restriction requirements during the course of chronic relapsing experimental allergic encephalomyelitis (CREAE), (SJL x PL)F1 mice were used as a model. EAE can be passively transferred in these mice by F1 T cells incubated with Ia-positive antigen-presenting cells (APC) from either parent SJL (H-2s) or PL (H-2u) and MBP fragments 89-169 or 1-37, respectively. T cells purified from F1 mice immunized with MBP fragment 1-37 were positively selected for I-Au-supported proliferation by culture in the presence of irradiated Iau-positive PL spleen cells as APC. I-As-supported proliferation and proliferation to residues 89-169 were not detected following selection. Adoptive transfer of this T cell line induced CREAE in naive recipient F1 mice and 2 weeks after the second attack of EAE recipient proliferative responses were measured. Recipient T cells proliferated to both fragment 1-37 and fragment 89-169. Moreover, proliferation was supported by I-As-positive as well as I-Au-positive macrophages. These findings demonstrate that T cells with novel epitope specificities and class II restriction requirements can be generated during the course of CREAE and suggest the possibility that such cells may be involved in the pathogenesis of this chronic autoimmune illness.