Epstein-Barr virus-transformed lymphocytes produce monoclonal autoantibodies that react with antigens in multiple organs

The Heterogeneous Multiple Sclerosis Lesion: How Can We Assess and Modify a Degenerating Lesion?

Multiple sclerosis (MS) is a heterogeneous disease of the central nervous system that is governed by neural tissue loss and dystrophy during its progressive phase, with complex reactive pathological cellular changes. The immune-mediated mechanisms that promulgate the demyelinating lesions during relapses of acute episodes are not characteristic of chronic lesions during progressive MS. This has limited our capacity to target the disease effectively as it evolves within the central nervous system white and gray matter, thereby leaving neurologists without effective options to manage individuals as they transition to a secondary progressive phase. The current review highlights the molecular and cellular sequelae that have been identified as cooperating with and/or contributing to neurodegeneration that characterizes individuals with progressive forms of MS. We emphasize the need for appropriate monitoring via known and novel molecular and imaging biomarkers that can accurately detect and predict progression for the purposes of newly designed clinical trials that can demonstrate the efficacy of neuroprotection and potentially neurorepair. To achieve neurorepair, we focus on the modifications required in the reactive cellular and extracellular milieu in order to enable endogenous cell growth as well as transplanted cells that can integrate and/or renew the degenerative MS plaque.

The Role of Viral Infections in the Onset of Autoimmune Diseases

Autoimmune diseases (AIDs) are the consequence of a breach in immune tolerance, leading to the inability to sufficiently differentiate between self and non-self. Immune reactions that are targeted towards self-antigens can ultimately lead to the destruction of the host's cells and the development of autoimmune diseases. Although autoimmune disorders are comparatively rare, the worldwide incidence and prevalence is increasing, and they have major adverse implications for mortality and morbidity. Genetic and environmental factors are thought to be the major factors contributing to the development of autoimmunity. Viral infections are one of the environmental triggers that can lead to autoimmunity. Current research suggests that several mechanisms, such as molecular mimicry, epitope spreading, and bystander activation, can cause viral-induced autoimmunity. Here we describe the latest insights into the pathomechanisms of viral-induced autoimmune diseases and discuss recent findings on COVID-19 infections and the development of AIDs.

Prevalence of Epstein-Barr virus infection and characteristics of lymphocyte subsets in newly onset juvenile dermatomyositis

BACKGROUND

The underlying etiology of juvenile dermatomyositis (JDM) is unknown. T cell deficiency as well as Epstein-Barr virus (EBV) infection had been suspected to be involved in the pathogenesis, but it has been poorly evaluated in JDM patients.

METHODS

This study described the traits of T and B lymphocyte subsets in newly onset JDM patients and the incidence of EBV infection in JDM patients compared with match controls. Newly developed JDM patients from 2014 to 2018 were included in the study. Lymphocytes with different markers (CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺, CD3^-CD19⁺ and CD3^-CD16⁺CD56⁺) were tested with flow cytometry in the first admission or after 6 months of treatment. Statistical analysis was conducted to compare the EBV infection in the group of JDM patients and controls.

RESULTS

We observed that JDM patients had higher positive rate of Epstein-Barr nuclear antigen-immunoglobulin G (IgG) (P < 0.0001) as well as EBV capsid antigen-IgG (P < 0.05) than normal controls. CD3^-CD16⁺CD56⁺ lymphocyte was found to be extremely low in early stage of JDM patients, but increased after 6 months of treatment (P = 0.0091).

CONCLUSIONS

The level of CD3^-CD16⁺CD56⁺ cells may associate with the clinical course of JDM. EBV may act as an environmental factor predisposing patients to the development of JDM.

Immune System Sex Differences May Bridge the Gap Between Sex and Gender in Fibromyalgia

The fibromyalgia syndrome (FMS) is characterized by chronic widespread pain, sleep disturbances, fatigue, and cognitive alterations. A limited efficacy of targeted treatment and a high FMS prevalence (2–5% of the adult population) sums up to high morbidity. Although, altered nociception has been explained with the central sensitization hypothesis, which may occur after neuropathy, its molecular mechanism is not understood. The marked female predominance among FMS patients is often attributed to a psychosocial predisposition of the female gender, but here we will focus on sex differences in neurobiological processes, specifically those of the immune system, as various immunological biomarkers are altered in FMS. The activation of innate immune sensors is compatible with a neuropathy or virus-induced autoimmune diseases. Considering sex differences in the immune system and the clustering of FMS with autoimmune diseases, we hypothesize that the female predominance in FMS is due to a neuropathy-induced autoimmune pathophysiology. We invite the scientific community to verify the autoimmune hypothesis for FMS.

Hypothesis: Multiple sclerosis is caused by three-hits, strictly in order, in genetically susceptible persons

Multiple Sclerosis is a chronic, progressive and debilitating neurological disease which, despite extensive study for over 100 years, remains of enigmatic aetiology. Drawn from the epidemiological evidence, there exists a consensus that there are environmental (possibly infectious) factors that contribute to disease pathogenesis that have not yet been fully elucidated. Here we propose a three-tiered hypothesis: 1) a clinic-epidemiological model of multiple sclerosis as a rare late complication of two sequential infections (with the temporal sequence of infections being important); 2) a proposal that the first event is helminthic infection with Enterobius Vermicularis, and the second is Epstein Barr Virus infection; and 3) a proposal for a testable biological mechanism, involving T-Cell exhaustion for Epstein-Barr Virus protein LMP2A. We believe that this model satisfies some of the as-yet unexplained features of multiple sclerosis epidemiology, is consistent with the clinical and neuropathological features of the disease and is potentially testable by experiment. This model may be generalizable to other autoimmune diseases.

Association of Epstein-Barr virus infection with systemic lupus erythematosus in Taiwan

An association between Epstein-Barr virus (EBV) infection and systemic lupus erythematosus (SLE) has been suggested from previous serologic evidence. Since most adults in Taiwan are EBV-infected, seroepidemiologic studies based on standard assays for EBV are unlikely to dissociate SLE patients and control groups. We reexamine this question by using novel methodologies in which IgA anti-EBV-coded nuclear antigens-1 (EBNA-1) and IgG anti-EBV DNase antibodies were analysed by ELISA, and EBV viral loads were detected by real-time quantitative PCR for 93 adult SLE patients and 370 age-, sex- and living place-matched healthy controls in Taiwan. The specificities of antibodies for extractible nuclear antigens were determined by Western blot. Our results show that IgA anti-EBV EBNA1 antibodies were detectable in 31.2% SLE patients but only in 4.1% of controls (odds ratio [OR] = 10.72, 95% confidence interval [CI] = 5.19–22.35; P < 10-7), IgG anti-EBV DNase antibodies were detected in 53.8% SLE patients but only in 12.2% controls (OR = 8.40, 95% CI = 4.87–14.51; P < 10-7). EBV DNA was amplifiable from the sera of 41.9% SLE patients but from only 3.24% controls ( P < 0.05). A significant association of IgG anti-EBV DNase antibodies with anti-Sm/RNP antibodies was observed ( P < 0.005). The higher seroreactivity and higher copy numbers of EBV genome indicated association of EBV infection with SLE in Taiwan.

Epstein-barr virus as a trigger of autoimmune liver diseases

The pathogenesis of autoimmune diseases includes a combination of genetic factors and environmental exposures including infectious agents. Infectious triggers are commonly indicated as being involved in the induction of autoimmune disease, with Epstein-Barr virus (EBV) being implicated in several autoimmune disorders. EBV is appealing in the pathogenesis of autoimmune disease, due to its high prevalence worldwide, its persistency throughout life in the host's B lymphocytes, and its ability to alter the host's immune response and to inhibit apoptosis. However, the evidence in support of EBV in the pathogenesis varies among diseases. Autoimmune liver diseases (AiLDs), including autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC), have a potential causative link with EBV. The data surrounding EBV and AiLD are scarce. The lack of evidence surrounding EBV in AiLD may also be reflective of the rarity of these conditions. EBV infection has also been linked to other autoimmune conditions, which are often found to be concomitant with AiLD. This paper will critically examine the literature surrounding the link between EBV infection and AiLD development. The current evidence is far from being conclusive of the theory of a link between EBV and AiLD.

CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis

CD8+ T-cell deficiency is a feature of many chronic autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, dermatomyositis, primary biliary cirrhosis, primary sclerosing cholangitis, ulcerative colitis, Crohn's disease, psoriasis, vitiligo, bullous pemphigoid, alopecia areata, idiopathic dilated cardiomyopathy, type 1 diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, myasthenia gravis, IgA nephropathy, membranous nephropathy, and pernicious anaemia. It also occurs in healthy blood relatives of patients with autoimmune diseases, suggesting it is genetically determined. Here it is proposed that this CD8+ T-cell deficiency underlies the development of chronic autoimmune diseases by impairing CD8+ T-cell control of Epstein-Barr virus (EBV) infection, with the result that EBV-infected autoreactive B cells accumulate in the target organ where they produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells which would otherwise die in the target organ by activation-induced apoptosis. Autoimmunity is postulated to evolve in the following steps: (1) CD8+ T-cell deficiency, (2) primary EBV infection, (3) decreased CD8+ T-cell control of EBV, (4) increased EBV load and increased anti-EBV antibodies, (5) EBV infection in the target organ, (6) clonal expansion of EBV-infected autoreactive B cells in the target organ, (7) infiltration of autoreactive T cells into the target organ, and (8) development of ectopic lymphoid follicles in the target organ. It is also proposed that deprivation of sunlight and vitamin D at higher latitudes facilitates the development of autoimmune diseases by aggravating the CD8+ T-cell deficiency and thereby further impairing control of EBV. The hypothesis makes predictions which can be tested, including the prevention and successful treatment of chronic autoimmune diseases by controlling EBV infection.

Cardiac myosin and autoimmune myocarditis

Infection with type 3 of the group B Coxsackieviruses (CB3) sometimes leads to the development of myocarditis in humans. Circumstantial evidence in the form of heart-reactive antibodies in these cases of human myocarditis suggests that the later phases of the disease may be due to autoimmunization. Since human myocarditis is a relatively rare sequel to infection with CB3 virus, we propose that it reflects a genetic predisposition in some individuals. To investigate this possibility we established an experimental murine model of viral myocarditis. By testing a large number of strains of inbred mice infected with CB3 we found that a few strains developed an ongoing myocarditis characterized by diffuse interstitial mononuclear infiltration and by the production of heart-specific IgG autoantibodies. These antibodies reacted with myocardial sarcolemma and myofibrils as well as with muscle striations. The principal myocardial autoantigen, identified by means of postinfectious sera of mice with heart-specific autoantibodies, was found to be the cardiac isoform of myosin. Immunization of susceptible mice with cardiac myosin stimulated the production of heart-specific antibodies reactive with both cardiac muscle striations and sarcolemma, accompanied by mononuclear infiltration of the myocardium. From these results we infer that cardiac myosin is an autoantigen capable of inducing postinfectious myocarditis in genetically predisposed individuals.

EBV latent membrane protein 2A induces autoreactive B cell activation and TLR hypersensitivity

EBV is associated with systemic lupus erythematosus (SLE), but how it might contribute to the etiology is not clear. Since EBV-encoded latent membrane protein 2A (LMP2A) interferes with normal B cell differentiation and function, we sought to determine its effect on B cell tolerance. Mice transgenic for both LMP2A and the Ig transgene 2-12H specific for the ribonucleoprotein Smith (Sm), a target of the immune system in SLE, develop a spontaneous anti-Sm response. LMP2A allows anti-Sm B cells to overcome the regulatory checkpoint at the early preplasma cell stage by a self-Ag-dependent mechanism. LMP2A induces a heightened sensitivity to TLR ligand stimulation, resulting in increased proliferation or Ab-secreting cell differentiation or both. Thus, we propose a model whereby LMP2A induces hypersensitivity to TLR stimulation, leading to activation of anti-Sm B cells through the BCR/TLR pathway. These data further implicate TLRs in the etiology of SLE and suggest a mechanistic link between EBV infection and SLE.

T Cell Reactivity during Infectious Mononucleosis and Persistent Gammaherpesvirus Infection in Mice

Intranasal infection of mice with murine gammaherpesvirus 68 causes a dramatic increase in numbers of activated CD8(+) T cells in the blood, analogous in many respects to EBV-induced infectious mononucleosis in humans. In the mouse model, this lymphocytosis has two distinct components: an early, conventional virus-specific CD8(+) T cell response, and a later response characterized by a dramatic increase among CD8(+) T cells that bear Vbeta4(+) TCRs. We previously demonstrated that Vbeta4(+)CD8(+) T cells recognize an uncharacterized ligand expressed on latently infected B cells in an MHC-independent manner. The frequency of Vbeta4(+)CD8(+) T cells increases dramatically following the peak of viral latency in the spleen. In the current studies, we show that elevated Vbeta4(+)CD8(+) T cell levels are sustained long-term in persistently infected mice, apparently a consequence of continued ligand expression. In addition, we show that Vbeta4(+)CD8(+) T cells can acquire effector functions, including cytotoxicity and the capacity to secrete IFN-gamma, although they have an atypical activation profile compared with well-characterized CD8(+) T cells specific for conventional viral epitopes. The characteristics of Vbeta4(+)CD8(+) T cells (potential effector function, stimulation by latently infected B cells, and kinetics of expansion) suggested that this dominant T cell response plays a key role in the immune control of latent virus. However, Ab depletion and adoptive transfer studies show that Vbeta4(+)CD8(+) T cells are not essential for this function. This murine model of infection may provide insight into the role of unusual populations of activated T cells associated with persistent viral infections.

Infection of autoreactive B lymphocytes with EBV, causing chronic autoimmune diseases

I hypothesize that human chronic autoimmune diseases are based on infection of autoreactive B lymphocytes by Epstein-Barr virus (EBV), in the following proposed scenario. During primary infection, autoreactive B cells are infected by EBV, proliferate and become latently infected memory B cells, which are resistant to the apoptosis that occurs during normal B-cell homeostasis because they express virus-encoded anti-apoptotic molecules. Genetic susceptibility to the effects of B-cell infection by EBV leads to an increased number of latently infected autoreactive memory B cells, which lodge in organs where their target antigen is expressed, and act there as antigen-presenting cells. When CD4(+) T cells that recognize antigens within the target organ are activated in lymphoid organs by cross-reactivity with infectious agents, they migrate to the target organ but fail to undergo activation-induced apoptosis because they receive a co-stimulatory survival signal from the infected B cells. The autoreactive T cells proliferate and produce cytokines, which recruit other inflammatory cells, with resultant target organ damage and chronic autoimmune disease.

A mouse model for infectious mononucleosis

Epstein-Barr virus (EBV) is a ubiquitous human gamma-herpesvirus that establishes life-long latency and is associated with lymphoproliferative disorders and the development of several malignancies. EBV infection is frequently, but not always, associated with the development of a syndrome termed infectious mononucleosis. The recent isolation and characterization of a murine gamma-herpesvirus, MHV-68 (gammaHV-68) has provided the first small animal model for studying immunity and pathogenesis of a gamma-herpesvirus in its natural host. MHV-68 has important biological and genetic similarities with the human gamma-herpesviruses. Following intranasal infection of mice with MHV-68, an acute respiratory infection in the lung develops and is cleared, followed by the establishment of latency. Similar to EBV, MHV-68 latency is largely established in B cells, although other cell types can be latently infected. The establishment of latency correlates with a prominent splenomegaly, polyclonal B cell activation with associated autoantibody production, and CD8+ T cell-dominated peripheral blood lymphocytosis, in many aspects mirroring EBV-induced infectious mononucleosis. There are key differences in the MHV-68- and EBV-induced CD8+ T cell responses however. Whereas the expanded CD8+ T cells associated with EBV-induced mononucleosis are largely the outgrowth of T cells responding to lytic viral epitopes elicited during the acute phase of the response, the CD8+ T cell lymphocytosis associated with MHV-68-induced infectious mononucleosis is dominated by an oligoclonal population of T cells expressing Vbeta4+ T cell receptors that are not reactive to acute viral epitopes. The focus of this article will be to highlight the similarities and differences in the infectious mononucleosis syndrome associated with human and murine gamma-herpesviruses.

Neurological complications of acute and persistent Epstein-Barr virus infection in paediatric patients

Neurological complications of Epstein-Barr virus (EBV) have been reported almost exclusively in the course of acute primary infections. The role of EBV in paediatric neurological disease was investigated prospectively over a 2-year period, searching for acute primary, chronic, and reactivated EBV infections. Active EBV infections were diagnosed in 10/48 patients, including two with acute primary EBV infections (cranial neuritis and cerebellitis), one with chronic active infection (T/NK cell lymphoma with cranial neuritis), and seven with reactivated infections. Among these seven patients, three showed "Alice in Wonderland" syndrome, one facial nerve palsy, one progressive macrocephaly, and two prolonged encephalitic illness. The prognosis was good except for the patient with lethal T/NK cell lymphoma and the two girls with encephalitic illness. Despite steroid treatment, these girls suffered prolonged cognitive impairment and epileptic seizures. Both developed left-sided hippocampal atrophy, and one of them hippocampal sclerosis. Like primary infections, reactivated EBV infections cause neurological complications in a considerable number of paediatric patients, lead to serious long-term complications, and may contribute to the pathogenesis of hippocampal lesions.

Autoantibodies to tubulin are specifically associated with the young age onset of the nasopharyngeal carcinoma

By far the highest incidence of the Epstein-Barr virus (EBV)-associated nasopharyngeal carcinomas in young subjects was found in North Africa, a region of intermediate risk for adults. We used the immunofluorescence analysis and ELISA to characterize the presence of IgG autoantibodies to the cytoskeleton and nuclear proteins in sera of 82 Tunisian patients with primary nasopharyngeal carcinoma and those of 82 healthy subjects. To assess the specificity of the sera autoreactivity, inhibition tests were carried out using free autoantigens. Analysis of sera autoreactivity in patients with nasopharyngeal carcinoma and in control subjects showed that 23% of the patients had serum reactivity against more than 1 autoantigen tested compared to 1.2% in the control group (p = 10(-4)). The most frequent auto reactivity in patient's sera was found with tubulin and nuclear proteins (19.5% and 22% respectively vs. 6.1% and 1.2% in controls). The IgG auto reactivity inhibition studies indicate that all autoantigens, except native DNA, showed low values of IC(50) (concentration of antigen causing 50% inhibition of the antibody binding) reflecting the high affinity of these IgG autoantibodies. When patients and controls were stratified according to their age, IgG autoantibodies to tubulin were found specifically associated with the young age onset of the nasopharyngeal carcinoma (age under 25 years). IgG auto reactivity comparison before and after cancer therapy showed that only anti-tubulin reactivity was significantly affected by treatment. Our results demonstrate that the autoantibodies to the cytoskeleton and nuclear proteins are associated with the nasopharyngeal carcinoma in Tunisians. The anti-tubulin IgG autoantibodies may represent a serologic marker for the nasopharyngeal carcinoma in children and adolescents Tunisians.

Analysis of the virus-specific and nonspecific B cell response to a persistent B-lymphotropic gammaherpesvirus

Respiratory challenge of mice with murine gammaherpesvirus 68 (gammaHV68) results in acute replication in respiratory epithelial cells and persistent, latent infection of B cells and macrophages. gammaHV68 elicits virus-specific Ab, and also nonspecifically activates B cells to Ab production through a CD4+ T cell-dependent process. The current analysis characterizes virus-specific and nonspecific Ab production at the single cell level and investigates the requirements and nature of the nonspecific response. Virus-specific Ab-forming cell (AFC) numbers were dwarfed by the increase in total AFC in all sites examined, indicating substantial nonspecific Ab production. Clear increases and decreases in specific and total AFC numbers occurred in the lymph nodes draining the respiratory tract and the spleen, but AFC numbers in the bone marrow (BM) increased to a plateau and remained constant. The longevity of the BM response was reflected in a sustained increase in virus-specific and total serum Ab levels. Generally, the IgG2a and IgG2b isotypes predominated. Analysis of cytokine-deficient mice, CD40 ligand-deficient mice, and radiation BM chimeras lacking MHC class II expression specifically on B cells indicated that nonspecific Ab production is independent of IL-6 or IFN-gamma, and dependent on cognate CD4+ T cell help. Several observations were consistent with polyclonal B cell activation by gammaHV68, including the induction of durable serum levels of IgG reactive with mammalian dsDNA and murine type II collagen. Our findings indicate new directions for studies of this valuable model of gamma-herpesvirus pathogenesis.

Polyreactive antigen-binding B cells in the peripheral circulation are IgD+ and B7-

Polyreactive antibodies are naturally occurring antibodies, primarily of the IgM isotype, that are capable of reacting with a wide variety of different self and non-self antigens. Previously, we reported that a B cell capable of making polyreactive antibody has Ig receptors on its surface that can bind different antigens. The present investigation was initiated to characterize these polyreactive antigen-binding B cells further. A panel of fluorescein isothiocyanate-labeled antigens (insulin, IgG Fc fragment or beta-galactosidase) served as probes to select polyreactive antigen-binding B cells by cell sorting. Our experiment revealed that these polyreactive antigen-binding B cells were mainly of the IgD isotype. They expressed high levels of CD40 and major histocompatibility complex class II molecules, but little or no B7-1, B7-2, or Fas. In contrast to the binding of antigens to monoreactive receptors (usually high affinity), the binding of antigens to polyreactive receptors (usually moderate or low affinity) did not up-regulate the expression of B7-1 or B7-2. Antigens that bound to polyreactive receptors, however, were internalized and degraded, although not as efficiently as antigens that bound to monoreactive receptors. Despite the ability of these B7- cells to process antigens, they were not able to activate T cells in a mixed leukocyte reaction. It is concluded that polyreactive antigen-binding B cells have properties that are consistent with the ability to induce immunological tolerance.

Antigen-binding B cells and polyreactive antibodies

The present experiments were initiated to see if cells capable of binding antigens could make polyreactive antibodies. Fluorescein isothiocyanate-labeled self and non-self antigens were incubated with B cells from normal individuals. Antigen-binding cells were separated from non-antigen-binding cells by flow cytometry, immortalized with Epstein-Barr virus and analyzed at the clonal level for their capacity to make polyreactive antibodies. Four to six times more cells making polyreactive antibodies were found in the B cell subset that bound antigens than in the B cell subset that did not bind antigens. The majority of the polyreactive antibodies were of the immunoglobulin (Ig)M isotype. Immunoflow cytometry revealed that cell lines making polyreactive antibodies bound a variety of antigens (e.g., insulin, IgGFc and beta-galactosidase), whereas cell lines making monoreactive antibodies bound only a single antigen. The binding of antigens to B cell lines that made polyreactive antibodies could be inhibited (range, 28%-57%) by both homogeneous and heterogeneous antigens. Both CD5+ and CD5- antigen-binding B cells made polyreactive antibodies, but the frequency was slightly higher in the CD5+ antigen-binding (85%) as compared to the CD5- antigen-binding (50%) population. Comparison of CD5+ B cells that bound antigens with CD5+ B cells that did not bind antigens showed that approximately 86% of the former, but only 15% of the latter, made polyreactive antibodies. It is concluded that cells capable of binding a variety of different antigens can make polyreactive antibodies and that antigen binding is a good marker for identifying polyreactive antibody-producing cells.

Malignant lymphoma of the thyroid with evidence of an Epstein-Barr viral infection concomitant with thalassemia minor: report of a case

We report herein the unusual case of a 53-year-old Japanese man in whom malignant lymphoma of the thyroid was found to coexist with asymptomatic thalassemia minor and an elevated titer (1:80) of immunoglobulin G against the Epstein-Barr viral capsid antigen. A total thyroidectomy with lymphadenectomy was performed, and the thyroid was found to be almost replaced by the neoplasm, the microscopy of which revealed malignant lymphoma of the diffuse, large-cell type. The existence of this case led us to question whether malignant lymphoma of the thyroid and an elevated titer for the Epstein-Barr virus might have a possible mutual association.

Viral antibodies in infectious mononucleosis

Patients with Epstein-Barr virus (EBV) infectious mononucleosis (IM) usually develop heterophilic antibodies and some autoantibodies. Antibodies to rubella, measles, adeno-, entero-, herpes simplex, cytomegalo- and varicella-zoster viruses were titrated in sera from IM patients and matched healthy controls using the complement fixation test (CFT) and the haemagglutination inhibition test. Except for herpes simplex virus and cytomegalovirus, the IM sera had significantly higher arithmetical and geometrical mean antibody titres and showed in most cases higher antibody prevalences in the CFT. The titre rise was most pronounced for rubella and measles antibodies, between 2- and 3-fold. There were no cases of very high titres occasionally seen in IM. The IM sera had higher total IgG serum levels than the controls, 17.27 g/l and 11.8 g/l, respectively (P < 0.001). The present data show that in addition to previously reported high levels of some autoantibodies and of heterophilic antibodies, there is a more general increase in IgG antibodies to commonly occurring viruses. This increase is most likely due to the polyclonal activation of B-lymphocytes following the binding of EBV to the complement receptor CR2 (CD21). When due consideration is given to the possible occasional occurrence of a false positive rubella IgM test, the raised antibody-titres will most likely not interfere with routine diagnostics.

Epstein-Barr virus-transformed human B lymphocytes produce natural antibodies to histones

To study the mechanism(s) responsible for the appearance of Epstein-Barr virus (EBV)-induced anti-histone autoantibodies, peripheral blood B lymphocytes from healthy donors were infected with EBV and the resulting lymphoblastoid cell lines were tested for secretion of antibodies reacting with histones. It was found that EBV-transformed cells produce IgM antibody reactive with histones and that the frequency of EBV-inducible circulating B lymphocytes that produce antibodies to histones is at least 10(-5). Moreover, in cultures of tonsillar lymphoid cells, the enrichment in CD5+ B lymphocytes increases the percentage of EBV-transformed cultures making anti-histone IgM antibodies. EBV may therefore, also in vivo, induce natural anti-histone antibody by polyclonal B-cell activation without any requirement of antigen to trigger antibody response.

Human monoclonal islet cell antibodies from a patient with insulin-dependent diabetes mellitus reveal glutamate decarboxylase as the target antigen

The autoimmune phenomena associated with destruction of the beta cell in pancreatic islets and development of type 1 (insulin-dependent) diabetes mellitus (IDDM) include circulating islet cell antibodies. We have immortalized peripheral blood lymphocytes from prediabetic individuals and patients with newly diagnosed IDDM by Epstein-Barr virus transformation. IgG-positive cells were selected by anti-human IgG-coupled magnetic beads and expanded in cell culture. Supernatants were screened for cytoplasmic islet cell antibodies using the conventional indirect immunofluorescence test on cryostat sections of human pancreas. Six islet cell-specific B-cell lines, originating from a patient with newly diagnosed IDDM, could be stabilized on a monoclonal level. All six monoclonal islet cell antibodies (MICA 1-6) were of the IgG class. None of the MICA reacted with human thyroid, adrenal gland, anterior pituitary, liver, lung, stomach, and intestine tissues but all six reacted with pancreatic islets of different mammalian species and, in addition, with neurons of rat cerebellar cortex. MICA 1-6 were shown to recognize four distinct antigenic epitopes in islets. Islet cell antibody-positive diabetic sera but not normal human sera blocked the binding of the monoclonal antibodies to their target epitopes. Immunoprecipitation of 35S-labeled human islet cell extracts revealed that a protein of identical size to the enzyme glutamate decarboxylase (EC 4.1.1.15) was a target of all MICA. Furthermore, antigen immunotrapped by the MICA from brain homogenates showed glutamate decarboxylase enzyme activity. MICA 1-6 therefore reveal glutamate decarboxylase as the predominant target antigen of cytoplasmic islet cell autoantibodies in a patient with newly diagnosed IDDM.

Cytotoxic and viral neutralizing antibodies crossreact with streptococcal M protein, enteroviruses, and human cardiac myosin

The development of autoimmunity in certain instances is related to infectious agents. In this report, cytotoxic monoclonal antibodies (mAbs) that recognize epitopes on both enteroviruses and the bacterium Streptococcus pyogenes are described. Murine anti-streptococcal mAbs that were crossreactive with streptococcal M protein, human cardiac myosin, and other alpha-helical coiled-coil molecules were found to neutralize coxsackieviruses B3 and B4 or poliovirus type 1. The viral-neutralizing anti-streptococcal mAbs were also cytotoxic for heart and fibroblast cell lines and reacted with viral capsid proteins on a Western immunoblot. Alignment of amino acid sequences shared between streptococcal M protein, coxsackie-virus B3 capsid protein VP1, and myosin revealed 40% identity in a 14- to 15-amino acid overlap. Synthetic peptides containing these sequences blocked mAb reactivity with streptococcal M protein. The data show that antibodies against alpha-helical structures of bacterial and viral antigens can lead to cytotoxic reactions and may be one mechanism to explain the origin of autoimmune heart disease.

Evidence for polyclonal B cell activation as the mechanism for LCMV-induced autoimmune hemolytic anemia

A docile substrain of lymphocytic choriomeningitis virus (LCMV) causes a persistent infection in adult C3HeB mice and induces a severe autoimmune hemolytic anemia (AIHA) which is maximal around three weeks post infection (PI). Evaluations of serum immunoglobulin levels of these mice demonstrated grossly elevated IgG2a levels along with increased IgG1 and IgG2b levels, suggesting that these animals also develop polyclonal B cell activation (PBA). Interestingly, LCMV-infected B10.BR mice did not demonstrate a marked hypogammaglobulinemia nor did they experience a severe hemolytic anemia. Although evaluations of the hematocrits indicated that these animals endure a mild anemia 21 days PI, a below normal reticulocyte count until day 18 PI suggests that there was a prolonged suppression in hematopoiesis. It is clear from RBC survival studies that there is not an accelerated rate of RBC elimination, as seen in infected C3H mice, demonstrating that the anemia in B10.BR mice is not due to a hemolytic process. These results imply a correlation between the development of PBA and AIHA, suggesting a cause and effect relationship.

Detection of an idiotope on a human monoclonal autoantibody by monoclonal anti-idiotypic antibody and its relationship to Epstein-Barr virus-induced autoimmunity

We have recently described a human IgM monoclonal antibody (mAb), reactive with both self antigens, i.e., cytoskeleton filaments and smooth muscle, and Epstein-Barr virus (EBV)-induced nuclear antigen (EBNA), produced by EBV-transformed B lymphocytes isolated from a patient with infectious mononucleosis (IM). In order to achieve higher antibody secretion in culture supernatant, the mAb-producer cells were fused with ouabain-resistant mouse myeloma cells and a stable human-mouse heterohybrid, coded HY 5488, producing up to 80 micrograms/ml IgM mAb, was isolated after 4 cloning procedures. Purified HY 5844 mAb was used to immunize mice for the production of a murine anti-idiotypic mAb, which was used to probe the expression of the idiotope of HY 5488 mAb (Id 5488) in sera of IM patients and normal controls by ELISA. It was found that Id 5488 is expressed both in IM patients and normal controls, and that Id 5488 expression is significantly higher in IM patients' sera; furthermore, in IM sera a statistically significant correlation between Id 5488 expression and anti-cytoskeleton and anti-smooth muscle autoantibodies was found. It is suggested that at least part of EBV-induced IgM autoantibodies appearing during IM are secreted by B lymphocytes programmed to the production of "natural antibodies" bearing Id 5488-like idiotopes.

Organ specificity of the antigens reacting with the 48-1 and S-1 antibodies in chimpanzees infected with hepatitis C virus

48-1 and S-1 antibodies produced by lymphoblastoid cells transformed with Epstein-Barr virus were reported to be associated with infection by not only the hepatitis non-A, non-B (NANB) virus but also hepatitis delta virus. Appearance of the antigens reacting with these antibodies in the liver of chimpanzees was recently found to be a host response to alpha-interferon induced by infections of both viruses. To investigate organ specificity of these antigens, various organs obtained from chimpanzees with hepatitis C (NANB) were examined. In addition to the liver, the adrenals and spleen were found to be positive by immunofluorescence. The positive reactions of these three organs were also confirmed by radioimmunoassay. By electron microscopy, microtubular aggregates similar to those observed in the liver were detected in the adrenals, but not in the spleen. The results suggested that these antigens existed in the liver, adrenal, and probably spleen of chimpanzees infected with hepatitis C.

Cloning of the latency gene and the early protein 0 gene of pseudorabies virus

A collection of overlapping cDNA clones encoding the latency transcript of pseudorabies virus and the DNA nucleotide sequence of the latency gene has been obtained. The transcript is spliced with 4.6 kb of intervening sequences. This mRNA, designated the large latency transcript, is 8.5 kb. It is polyadenylated and contains a large open reading frame capable of coding for a 200-kDa polypeptide. The direction of transcription is antiparallel to that of the immediate-early gene IE180 and a newly identified early gene, EP0. The latency transcript overlaps the entire IE180 gene and most of the EP0 gene. The EP0 mRNA is 1.75 kb and polyadenylated. The deduced amino acid sequence revealed the presence of cysteine-rich zinc finger domain similar to that of the immediate-early gene ICP0 of herpes simplex virus type 1 and the gene 61 polypeptide of varicella-zoster virus. On the basis of the biological functions, conserved protein domains, and unique spatial arrangements of the homologous polypeptides (IE180 versus ICP4 and EP0 versus ICP0) between pseudorabies virus and herpes simplex virus type 1, it is predicted that a homologous protein domain is also encoded by the 8.5-kb large latency transcripts of these two viruses.

Human monoclonal antibodies demonstrate polyreactivity for histones and the cytoskeleton

Systemic lupus erythematosus (SLE) and other autoimmune diseases are characterized by immune responses to intracellular, highly conserved antigens such as DNA and histone. In this study, peripheral blood lymphocytes (PBL) from a patient with histone autoantibodies were used to prepare IgM human-human hybridoma cell lines. Indirect immunofluorescence (IIF) was used to identify monoclonal antibodies that bound to cytoskeletal and other cytoplasmic constituents. These supernatants did not bind double-stranded or single-stranded DNA. However, immunoblotting revealed that 7/20 hybridomas selected for their binding to cytoskeletal components produced antibodies that also bound mammalian and avian histones. When peptide fragments of histone were used in immunoblotting experiments, it was found that the monoclonal antibodies bound to the carboxyl terminus of H1, a region previously shown to bind autoantibodies from sera of patients with SLE and drug-induced lupus (DIL). When the amino acid sequences of histones and cytoskeletal components were compared using the Swiss-Prot protein data bank, it was confirmed that there are eight regions of similarity. While the significance of polyreactive human monoclonal antibodies to cytoskeletal components and histones is not understood at present, it is possible that the human histone antibodies represent polyreactive antibodies that arise through the mechanism of molecular mimicry.

Xenopus oocytes as immunological vectors to produce monoclonal antibodies to rat brain antigens

A novel approach was developed to raise a panel of monoclonal antibodies (mAb) against brain antigens using Xenopus oocytes as immunological vectors. Xenopus oocytes were injected to express proteins encoded by brain-derived mRNA extracted from rat cerebral cortex. A crude membrane preparation from mRNA-injected oocytes was then used to immunize mice previously rendered immunotolerant to native oocyte membranes. mAb reacting with cryostat cut sections from rat brain were selected and further characterized by immunohistological and immunobiochemical techniques. Several mAb recognized brain specific antigens, including some that were cell type specific and others that revealed a regional binding pattern. A particular group of antibodies recognized an epitope localized exclusively to the cerebellar pinceau terminals. Although some of the hybridomas found in this panel may be products of natural autoreactive lymphocytes, the presence of a specific immune response to mRNA expression products is discussed. These results indicate that mRNA injected oocytes are useful tools to raise mAb to study the molecular diversity of the nervous system.

Evidence for immune-mediated destruction as mechanism for LCMV-induced anemia in persistently infected mice

A docile substrain of lymphocytic choriomeningitis virus (LCMV) causes a persistent infection in adult C3HeB mice and induces a severe anemia, which, unlike the viremia, eventually resolves. Measurements of red blood cell (RBC) survival rates demonstrated an increased rate of RBC clearance in these animals, indicating a hemolytic process for the anemia. Normal clearance rates of RBCs from infected mice transfused into control mice suggested that there was not an intrinsic defect in these cells. It also appeared that RBC destruction was immune-mediated, as cyclophosphamide treatments prevented the onset of anemia in infected mice, whereas adoptive transfer (AT) of immune splenocytes into immunocompromised mice reestablished the condition. The AT experiments also demonstrated that the onset of anemia correlated with the functional state of the immune cells. In addition, opsonization of RBCs was demonstrated by macrophage phagocytosis, and the appearance of opsonized RBCs corresponded with the course of the anemia. These findings support a hypothesis of RBC opsonization and subsequent phagocytosis by macrophages of the reticuloendothelial system as the mechanism for RBC destruction in LCMV-induced hemolytic anemia.

Production of antikeratin autoantibodies by hybrid spleen cells of naive mice

The mechanism of the occurrence of natural antikeratin antibodies in human sera was studied using hybrid spleen cells obtained from experimentally naive or from immunized mice. Antikeratin antibodies were detected by enzyme-linked immunosorbent assay (ELISA) in 5.9-9.5% of the culture supernatants of fused spleen cells taken from naive mice. When mice were immunized with keratins, the number of supernatants containing antikeratin antibodies was increased to eight out of 51 (15.7%). When immunized with non-keratin materials such as activated human T cells, adult T-cell leukaemia cell lysates, and human T-cell lymphotropic virus type-I (HTLV-I), 16.7-20.8% of the supernatants were found to contain antikeratin antibodies by ELISA. The antikeratin antibodies in the supernatants showed cytoplasmic staining of keratinocytes in human as well as mouse skin by indirect immunofluorescence. The antibodies reacted with extracted human epidermal keratins by dot-blot and Western blot analysis. Most antikeratin antibodies in the supernatants did not show cross-reactivity with exogenous antigens used for immunization and vimentin-type intermediate-sized filaments. These findings demonstrate that B cells producing antikeratin antibodies are common in naive mice, and produce various types of antikeratin antibodies following specific activation with epidermal keratins and non-specific immunological stimuli.

Idiotypic interactions between normal human polyspecific IgG and natural IgM antibodies

Pooled normal human polyspecific IgG (IVIg) contain anti-idiotypes against a variety of autoantibodies from patients with autoimmune diseases and IgG autoantibodies present in IVIg. The present study indicates that IVIg may also react through idiotypic/anti-idiotypic interactions with human natural IgM antibodies. Sixty-four percent of IgM secreted by B lymphoid cell lines derived from B cells of healthy elderly donors and 18% of IgM secreted by cloned EBV-transformed cord B cells that were tested, bound through their variable region to F(ab')2 fragments of IVIg. The binding to 2,4,6-trinitrophenyl (TNP) of a polyreactive IgM with anti-TNP specificity, was inhibited by F(ab')2 fragments from IVIg, indicating the presence in IVIg of anti-idiotypes that may interfere with the antibody-combining site of polyreactive IgM antibodies. The ability of IgM antibodies to interact with idiotypes on IVIg was not related to the degree of polyreactivity of natural antibodies. Our observations further document that IVIg contain antibody specificities against Ig from normal individuals and suggest that IgG originating from the physiologically expressed repertoire may modulate the expression of the potential B cell repertoire. The results may be relevant to the suppressive effect of IVIg in autoimmune diseases.

Ocular disease associated with Epstein-Barr virus infection

Epstein-Barr virus (EBV) is a ubiquitous DNA virus of the herpesvirus genus with a high prevalence rate for antibody (about 90%) in the adult population. It is the most common causative agent of infectious mononucleosis syndrome. During recent years an increasing number of ocular disease entities have been reported to be linked to EBV infection. These entities include oculoglandular syndrome, conjunctivitis, dry eye, keratitis, uveitis, choroiditis, retinitis, papillitis and ophthalmoplegia. While EBV-specific serologic tests can now document recent and past primary infection with EBV and also identify patients manifesting atypical immunologic reactions to EBV, the lack of an animal model, the absence of clear-cut response to therapy and the paucity of documentation by culture render the pathogenesis uncertain or the association questionable in many of these cases.

Demonstration of "naturally occurring mitochondrial antibodies" in family members of patients with primary biliary cirrhosis

Sera from 81 healthy family members (including husbands) of 13 patients with primary biliary cirrhosis were tested by Western blotting against the antigen fractions M9 and M2 derived respectively from rat liver and beef heart mitochondria. Fifty-eight (70%) were positive and recognized four major (molecular weights 98 kD, 65 kD, 61 kD, 58 kD) and eight minor determinants (85 kD, 81 kD, 78 kD, 54 kD, 48 kD, 45 kD, 40 kD, 30 kD) labeled alpha-my. Each of the 58 sera recognized at least one of the four major polypeptides. In contrast, only 6% of 80 primary biliary cirrhosis patients had antibodies against one of these epitopes. Sera from 25 patients with different infectious disorders previously shown to react with submitochondrial particles by enzyme-linked immunosorbent assay also recognized at least one of the four major determinants. From these findings it was concluded that these antibodies may belong to the family of natural autoantibodies. Since they reacted with submitochondrial fractions, they were defined as "naturally occurring mitochondrial antibodies". The high incidence of "naturally occurring mitochondrial antibodies" in primary biliary cirrhosis-contact persons may be taken as indirect evidence for a contagious immunogenic agent circulating in the blood of primary biliary cirrhosis-patients. In contrast, the absence of "naturally occurring mitochondrial antibodies" in primary biliary cirrhosis-patients themselves implies that an underlying B-cell defect is responsible for this lack of antibody production. Considering the protective role of naturally occurring antibodies in general, this postulated B-cell defect could be a major factor in the etiopathogenesis of primary biliary cirrhosis.

The antibody repertoire of early human B cells. I. High frequency of autoreactivity and polyreactivity

Cord blood and fetal liver B cells were immortalized using Epstein-Barr virus, and IgM antibodies from the resulting lines and clones were examined for their binding to a variety of auto-antigens and micro-organisms by ELISA and fluorescence assays. Auto-antigens tested included Fc of IgG, ssDNA and dsDNA, cardiolipin, histones 1-4, collagens type I and II, thyroglobulin, cytoskeletal components, and a tissue section screen. Of 71 cell lines tested, all but 19 showed some autoreactivity. All 32 fetal liver lines reacted to some self-antigens. In cord blood clones, 16 out of 26 bound to auto-antigens. Many of the clones reacted with more than one auto-antigen and were 'polyreactive'. Some of the cord blood clones bound to extracts of micro-organisms, showing specificity for both endogenous and exogenous antigens. The high frequency of CD5+ B cells in the cord blood (greater than 50%) and fetal liver (greater than 70%) argues for many of these clones being derived from this subset. Therefore, our data support the concept that many 'early' B cells produce polyreactive IgM which can bind to a variety of different auto-antigens and micro-organisms. These IgM antibodies are similar to those described by others as 'natural antibodies'.

IgM autoantibodies against two cellular antigens always appear in acute Epstein-Barr virus infection

In the course of infectious mononucleosis, IgM antibodies are formed against 2 proteins present in nucleated and non-nucleated vertebrate cells. Antibodies were found in sera of all patients suffering from acute Epstein-Barr virus infection. In 40% of the cases these antibodies are monoclonal. Persons with former Epstein-Barr virus infection were negative. The antibodies against the 2 proteins were first detected in Raji cells with an IgM-specific immunofluorescence test. The proteins were demonstrated in extracts of different cells and tissues by immunoblot technique. The molecular weight of the proteins measured in SDS polyacrylamide gel electrophoresis was 26 kd and 29 kd, respectively. Their presence in the cells does not depend on the presence of the Epstein-Barr virus genome. The relevance of the new findings concerning diagnostics as well as pathogenetic aspects remains to be established.

Influence of Epstein-Barr virus infection on B lymphocyte responses in patients with rheumatoid arthritis

The influence of Epstein-Barr virus (EBV) infection on clinical and serological features of rheumatoid arthritis (RA) were studied. Patients with in-vivo activated, in-vitro spontaneously proliferating EBV-infected B lymphocytes had higher levels of serum IgG and IgA, and tended to have more extensive disease. The finding of in-vivo activated EBV-transformed B cells was not specific for RA but was also seen in patients with ankylosing spondylitis. When supernatants of spontaneously proliferating B-cell lines from patients with RA were studied, autoantibody reactivities comparable with those from patients with infectious mononucleosis were detected. These observations suggest that EBV infection might have a profound influence on B-lymphocyte responses and clinical course in patients with RA.

Epstein-Barr virus and rheumatoid arthritis: cellular and molecular aspects

Several lines of research have indicated a possible association of the Epstein-Barr virus and rheumatoid arthritis (RA). The earliest evidence suggested that RA patients develop a stronger humoral immune response to EBV nuclear antigens (EBNA) which may in part account for the increased titers of antibody to the RA nuclear antigen (RANA). It was then pointed out that mononuclear cells from RA patients may be impaired in their capacity to control EBV infection. This may be related to a decrease in the production of IFN gamma and a consequence of monocyte-derived inhibitory activities. These cellular defects, however, are not specific for RA and may rather be the result of chronic inflammatory responses. These findings and the lack of increased virus presence in RA tissues did not provide a strong basis for a possible association of EBV and RA. A new concept for this association is now being tested on the basis of the sequence homology between the genetic RA susceptibility determinant HLA DR4 and the EBV glycoprotein 110.

Mechanisms other than polyclonal B cell activation possibly involved in Epstein-Barr virus-induced autoimmunity

In order to verify whether Epstein-Barr virus (EBV)-induced polyclonal B cell activation is the major cause of autoimmunity during infectious mononucleosis (IM), we have investigated, by immunoblotting, the fine specificity of anti-smooth muscle autoantibodies (autoAbs) in the sera of IM patients. Furthermore, we have isolated a number of in vivo infected EBV-positive cell lines from a patient with IM and compared the reactivity of the secreted immunoglobulins (Igs) with that of serum autoAbs. The reactivity of anti-smooth muscle autoAbs was found to be closely restricted to three proteins of approximate molecular weights 54, 52 and 48 kD. Furthermore, none of 48 EBV-positive B cell lines shared any reactivity with serum autoantibodies. Taken together, these results suggest that EBV-induced autoimmunity is not a consequence of a random activation of B cells, but a specific phenomenon, requiring mechanisms other than polyclonal B cell activation.

Encephalitis among Cree children in northern Quebec

We report a neurological disease among Cree Indian children in a northern Quebec village. The disease manifests as severe mental retardation, cerebral atrophy with white matter changes and calcifications, and systemic immunological abnormalities. Eleven cases are known in five families. The familial incidence of cases and the high degree of parental consanguinity suggest a genetic contribution. We propose that this entity may be caused by an unusual viral infection in a genetically vulnerable host.

Serum antibodies to a normal cellular protein (P-65) in patients with Hodgkin's disease

Samples from the L-428 Hodgkin's cell line and from several other lymphoma cell lines were lysed and the soluble proteins were subjected to one- or two-dimensional gel electrophoresis. The separated proteins were transferred to nitrocellulose by the Western Blot technique; antibody reactivity was detected by an immunoperoxidase reaction. Of 152 sera from patients with Hodgkin's disease (HD) 26 (17%) reacted with protein P-65 whereas in the control group, consisting of 35 healthy persons and 20 patients with other malignant diseases only 1 serum was reactive. Thus, the difference between the two groups was highly significant (P less than 0.01). These antibodies were most common in stage III HD. Splenectomy had no effect on the incidence of these antibodies, and there seemed to be no correlation with B-symptoms or with the histological subtype.