Interferon responses of leukocytes in multiple sclerosis

Virus-Induced Demyelination: The Case for Virus(es) in Multiple Sclerosis

Multiple Sclerosis (MS) is the most common demyelinating disease of man with over 400,000 cases in the United States and over 2.5 million cases worldwide. There are over 64,000 citations in Pubmed dating back as far as 1887. Much has been learned over the past 129 years with a recent burst in therapeutic options (mostly anti-inflammatory) with newer medications in development that are neuroprotective and/or neuroreparative. However, with all these advancements the cause of MS remains elusive. There is a clear interplay of genetic, immunologic, and environmental factors that influences both the development and progression of this disorder. This chapter will give a brief overview of the history and pathogenesis of MS with attention to how host immune responses in genetically susceptible individuals contribute to the MS disease process. In addition, we will explore the role of infectious agents in MS as potential “triggers” of disease. Models of virus-induced demyelination will be discussed, with an emphasis on the recent interest in human herpesviruses and the role they may play in MS disease pathogenesis. Although we remain circumspect as to the role of any microbial pathogen in MS, we suggest that only through well-controlled serological, cellular immune, molecular, and animal studies we will be able to identify candidate agents. Ultimately, clinical interventional trials that either target a specific pathogen or class of pathogens will be required to make definitive links between the suspected agent and MS.

Anti-inflammatory mechanisms of IFN-γ studied in experimental autoimmune encephalomyelitis reveal neutrophils as a potential target in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) mediated by T helper (h)1 and/or Th17 CD4 T cells that drive inflammatory lesion development along with demyelination and neuronal damage. Defects in immune regulatory mechanisms are thought to play a role in the pathogenesis of MS. While an early clinical trial indicated that IFN-γ administration was detrimental to MS, studies in the mouse model of MS, experimental autoimmune encephalomyelitis (EAE), indicated that IFN-γ exhibits a number of anti-inflammatory properties within the CNS. These mechanisms include inhibition of IL-17 production, induction of regulatory T cells, T cell apoptosis and regulation of chemokine production. Mice deficient in IFN-γ or its receptor were instrumental in deciphering the anti-inflammatory properties of IFN-γ in the CNS. In particular, they revealed that IFN-γ is a major regulator of neutrophil recruitment into the CNS, which by a variety of mechanisms including disruption of the blood-brain-barrier (BBB) and production of reactive oxygen species are thought to contribute to the onset and progression of EAE. Neutrophils were also shown to be instrumental in EAE relapses. To date neutrophils have not been appreciated as a driver of MS, but more recently based largely on strong EAE data this view is being reevaluated by some investigators in the field.

Plasmacytoid dendritic cells of the gut: relevance to immunity and pathology

Plasmacytoid dendritic cells (pDCs) are bone marrow-derived immune cells with the ability to express copious amounts of type I and III interferon (IFN) and can differentiate into antigen-presenting dendritic cells as a result of stimulation by pathogen-derived nucleic acid. These powerful combined functionalities allow pDCs to bridge the innate and adaptive immune systems resulting in a concerted pathogen response. The contribution of pDCs to gastrointestinal immunity is only now being elucidated and is proving to be a critical component in systemic immunity. This review will explore the immunology of pDCs and will discuss their involvement in human disease and tolerance with an emphasis on those in the gastrointestinal lymphoid tissue.

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Interferon-beta treatment for multiple sclerosis

Multiple sclerosis (MS) is the leading nontraumatic cause of neurologic disability in young adults. Interferon-beta, approved for use in 1993, was the first treatment to modify the course and prognosis of the disease and remains a mainstay of MS treatment. Numerous large-scale clinical trials in early, active patient populations have established the clinical efficacy of interferon-beta in reducing relapses and delaying disability progression. Although its mechanism of action remains incompletely understood, a reduction in active lesions seen on magnetic resonance imaging implies primary anti-inflammatory properties, a mechanism supported by basic immunologic research. Variation in individual patient responsiveness to interferon-beta may be due to disease variability or differential induction of interferon-stimulated genes. The magnitude of the therapeutic effect appears to be similar among products, but the optimal dose, route, and frequency of administration of the drug remain uncertain.

Interferons in relapsing-remitting multiple sclerosis: are there benefits from long-term use?

Multiple sclerosis (MS) is one of the most common chronic neurological diseases in young adults in western countries. An important aspect of treatment of this disease is the use of interferons (IFNs). These are molecules with antiviral, immunomodulatory, antiproliferative and hormonal activities. IFNbeta, a class I IFN, has been used extensively in the therapy of MS, particularly in its relapsing-remitting (RRMS) phase, the most frequent clinical form of the disease. Although the available evidence from published clinical trials is difficult to evaluate because of methodological differences, an unbiased review of the data reveals sufficient evidence to conclude that treatment with IFNbeta in RRMS is both efficacious and safe, at least over the periods so far investigated (up to 4-6 years). While there is no reason to suspect that IFNbeta should not continue to be efficacious and safe over the longer term, studies investigating these questions over longer periods and including greater numbers of patients are needed.

Complex immunomodulatory effects of interferon-beta in multiple sclerosis include the upregulation of T helper 1-associated marker genes

Multiple sclerosis (MS) is considered an autoimmune disease that is mediated by proinflammatory T helper-1 lymphocytes. The putative mechanism of interferon-beta (IFN-beta), an approved treatment for MS, includes the inhibition of T-cell proliferation, blocking of blood-brain-barrier opening and T-cell transmigration into the brain via interference with cell adhesion, and the upregulation of anti-inflammatory cytokines. In the present study, a gene expression analysis of IFN-beta-treated peripheral blood mononuclear cells by cDNA microarray documents the broad effects of IFN-beta that are not purely anti-inflammatory. Specifically, we addressed the effect of IFN-beta on T helper-1 differentiation- or lineage markers such as the IL-12 receptor beta2 chain and the chemokine receptor CCR5 that have been implicated in the pathogenesis of MS. Both markers were significantly upregulated in vitro and in vivo under IFN-beta therapy, supporting that this cytokine exerts complex effects on the immune system. The combination of cDNA microarray and quantitative PCR will expand our knowledge of the immunological effects of such pleiotropic agents as IFN-beta, may provide a key to why certain patients fail to respond, and eventually may influence our view of the disease pathogenesis.

Cytokine flow cytometry differentiates the clinical status of multiple sclerosis (MS) patients

In this study we have examined intracellular cytokines in peripheral blood mononuclear cells (PBMC) of MS patients by flow cytometry (cytokine flow cytometry). MS progressive patients showed an increased number of cells producing interferon-gamma (IFN-gamma) after activation with phorbol 12-myristate 13-acetate and ionomycin, compared with patients with clinically inactive forms (P < 0001) and with healthy controls (P = 0001). These cells belonged to the CD4+ and CD8+ subsets in similar proportions. Clinically inactive patients showed a lower level of cells producing IL-2 than controls (P = 0.03) and active MS patients (P = 0.03). Most IL-2-producing cells were CD4+ lymphocytes, although a small part of the IL-2 was also produced by CD8+ cells. The percentage of cells producing simultaneously IL-2 and IFN-gamma was increased in active MS and they were mainly CD4+ lymphocytes. No differences in the production of IL-4 were observed between groups. However, we found an increased IL-10 production in clinically active MS patients (P = 0.03). Treatment with IFN-beta of active MS patients showed lower levels of cytokines when compared with untreated MS patients. This methodological approach could help in the follow up and therapeutic monitoring of MS patients.

Functional activity of immune cells in female MS-patients

Since the well documented immunological disturbances in patients suffering from multiple sclerosis are especially attributed to T-cells we felt it expedient to look also for the functional activity of lymphocytes, monocytes, granulocytes and natural killer cells in the peripheral blood of female MS-patients (n = 17) and healthy controls (n = 17). While MS-patients showed decreased levels of total lymphocytes, CD2(+)- and CD8(+)-cells the percentage of HLA-DR(+)-monocytes was increased, indicating a high activity level of these immune cells, whereas we could find no differences in the functional tests of monocytes, granulocytes and natural killer cells between MS-patients and healthy controls. The percentage of HLA-DR(+)-T-lymphocytes increased with the duration of the illness and support the stronger consideration of clinical staging.

Association of human herpes virus 6 (HHV-6) with multiple sclerosis: increased IgM response to HHV-6 early antigen and detection of serum HHV-6 DNA

Viruses have long been suggested to be involved in the etiology of multiple sclerosis (MS). This suggestion is based on (1) epidemiological evidence of childhood exposure to infectious agents and increase in disease exacerbations with viral infection; (2) geographic association of disease susceptibility with evidence of MS clustering; (3) evidence that migration to and from high-risk areas influences the likelihood of developing MS; (4) abnormal immune responses to a variety of viruses; and (5) analogy with animal models and other human diseases in which viruses can cause diseases with long incubation periods, a relapsing-remitting course, and demyelination. Many of these studies involve the demonstration of increased antibody titers to a particular virus, whereas some describe isolation of virus from MS material. However, no virus to date has been definitively associated with this disease. Recently, human herpesvirus 6 (HHV-6), a newly described beta-herpes virus that shares homology with cytomegalovirus (CMV), has been reported to be present in active MS plaques. In order to extend these observations, we have demonstrated increased IgM serum antibody responses to HHV-6 early antigen (p41/38) in patients with relapsing-remitting MS (RRMS), compared with patients with chronic progressive MS (CPMS), patients with other neurologic disease (OND), patients with other autoimmune disease (OID), and normal controls. Given the ubiquitous nature of this virus and the challenging precedent of correlating antiviral antibodies with disease association, these antibody studies have been supported by the detection of HHV-6 DNA from samples of MS serum as a marker of active viral infection.

Diminished production of type-I interferons and interleukin-2 in patients with multiple sclerosis

Several lines of evidence have supported the role of immunological mechanisms in the pathogenesis of multiple sclerosis (MS) and new immunomodulatory strategies for its treatment, e.g. subcutaneous application of interferon (IFN)-beta, have emerged. We investigated the ability of peripheral blood mononuclear cells (PBMC) in 21 consecutive patients with clinically definite MS to produce interferons and lymphokines in response to viral or mitogenic stimulation. Ten patients showed clinical signs of disease activity (acute relapse) and 11 patients were in a stable condition. Additionally, white blood count, leukocyte differentiation and lymphocyte subtyping were performed. A group of age-related healthy blood donors served as control (n=20). There was no difference between patients and controls in the production of IFN-gamma, tumor necrosis factor (TNF)-alpha and soluble interleukin (IL)-2 receptor. IFN-alpha and IFN-beta responsiveness, however, was significantly lower in patients with stable disease than in patients with active disease and controls (p<0.001). Furthermore, secretion of IL-2 after stimulation was significantly diminished in both patient groups as compared to the control group (p<0.01). Analysis of T-cell subsets revealed a significantly lower amount of CD8+ T-cells in patients with stable disease, leading to a significantly higher CD4/CD8 ratio in this group as compared to patients with active disease. Our study depicted an IL-2 deficiency in MS patients which is shared with other autoimmune diseases. In addition, our findings suggest that the ability to produce type-I IFNs, IFN-alpha and IFN-beta, is primarily impaired in MS patients and changes in correlation to the course of disease activity.

Immunomodulation with linomide: possible novel therapy for multiple sclerosis

Linomide, a synthetic quinoline carboxamide, has the ability to stimulate various lymphocyte subpopulations. We have shown its inhibitory effect on the clinical and histological signs of acute and chronic relapsing EAE. In these models linomide induces suppression of lymphocyte response to antigens, production of autoantibody, antigen presentation to specific T-cell lines and Mac-I expression, and induces activation of NK and suppressor-inducer cells. We have subsequently shown its inhibitory effect on clinical and MRI signs of patients with secondary progressive multiple sclerosis. Results of a double blind, placebo controlled, short term pilot study with p.o. linomide, showed a significant effect on the clinical disability scale (EDSS) (P = 0.045) and on the mean total number of new lesions in serial monthly MRI scans (P = 0.021). The increase of CD45Ra, CD8 and CD16 positive cells in linomide treated patients may indicate the importance of suppressor-inducer, suppressor and NK cells for the inhibition of the autoimmune response in the disease.

Natural alpha interferon in multiple sclerosis: results of three preliminary series

In three preliminary, sequential series conducted between 1987-1991, natural human leukocyte interferon-alpha [HuIFN(Le)] was evaluated in 49 interferon-naive multiple sclerosis (MS) patients. In this study, safety data are reported for all 49 patients, and efficacy data for 45 of 49, each patient having received 3-12 months of therapy during the initial study year with observation only in the second year. No major side-effects for HuIFN(Le) were observed at doses of 5-30 million international units (MIU) per week for 3-12 months, although severe fatigue caused some patient drop-outs prior to completion of 3 months of therapy. The relapse rate in patients having received HuIFN(Le), prospectively evaluated in two series (34 patients), was reduced by 80% at 2 years. An unexpected trend towards improved disability provoked a retrospective analysis. In the first year, 36 of 45 (80%) patients improved or stabilized (P = 0.0001); of these 26 of 45 (58%) improved and 10 of 45 (22%) stabilized (P = 0.0023, chi 2 = 9.3). In year 2, 34 of 45 (76%) were improved/stabilized (P = 0.001); of these, 24 of 45 (53%) remained improved and 10 of 45 (22%) remained stable (P = 0.01, chi 2 = 6.6). A trend to greater efficacy at the higher doses for longer periods of therapy, up to 12 months, was observed.

Human natural interferon-alpha producing cells

Interferons (IFNs) are critical components of the host immune system, serving as antiviral agents, immunomodulators and inhibitors of cell growth. Among peripheral blood mononuclear cells, the primary IFN-alpha-producing cell is a light density, HLA-DR+ cell negative for cell surface markers typical for T cells, B cells, monocytes, natural-killer or progenitor cells and has been tentatively termed the 'natural IFN-producing cell' or NIPC. Although present in very low frequency (approximately 1:1000 among peripheral blood mononuclear cells), the NIPC are very potent, with an individual cell able to produce 1-2 IU of IFN. In this review, the characteristics, phenotype, regulation and relationship of NIPC to human disease are discussed.

Interferon beta decreases T cell activation and interferon gamma production in multiple sclerosis

Interferons (IFN) are biological molecules with anti-viral, anti-proliferative and immunomodulatory actions. There is evidence that IFN-gamma increases the frequency of exacerbations of multiple sclerosis (MS) whereas IFN-beta may reduce their frequency. Here we present evidence that IFN-beta significantly decreases concanavalin A (Con A)-induced proliferation of peripheral blood mononuclear cells (PBMC) of MS patients and healthy individuals. Similar results were obtained when PBMC were activated through the T cell receptor (TcR) by anti-CD3 monoclonal antibody or independently of it by phorbol ester and Ca2+ ionophore. These effects of IFN-beta were also noted when IFN-gamma and IFN-beta were added together. Furthermore, IFN-beta decreased proliferation when added to cells that were already pre-activated. Activated CD4+ and CD8+ T cells were downregulated to approximately the same extent. Analysis of cytokine production showed that IFN-gamma production by Con A activated PBMC was increased in MS when compared to controls. IFN-beta significantly decreased IFN-gamma production in MS patients and control individuals. Con A activated cultures treated with IFN-beta showed decreased IL2R expression and accumulation of IL2. These results show that IFN-beta decreases T cell activation and IFN-gamma production in vitro, effects that may be beneficial in MS.

Contrasting effects of alpha, beta, and gamma interferons on nonspecific suppressor function in multiple sclerosis

Interferons are biological molecules with antiviral, antiproliferative, and immunomodulatory actions. Interferon alpha (IFN-alpha) and -beta are potentially useful in the treatment of multiple sclerosis (MS). IFN-gamma, in contrast, increases the frequency of exacerbations of MS. In this study, we compared the effect of recombinant human IFN-alpha, -beta, and -gamma on suppressor function in patients with MS. Nonspecific suppressor cell function, measured in a concanavalin A suppressor assay, was significantly decreased in 16 patients with progressive MS (mean percent suppression +/- SEM, 14.4 +/- 5.5 in patients with MS, 33.5 +/- 4.8 in 16 normal subjects; p less than 0.001). Recombinant human IFN-beta augmented suppressor function in MS to 45.4 +/- 5.1% (p less than 0.001) and in control subjects to 56.8 +/- 3.8% (p less than 0.001). Similarly, recombinant human IFN-alpha improved suppression in MS to 43.0 +/- 5.6% (p less than 0.001) and in control subjects to 51.1 +/- 5.9% (p less than 0.001). In contrast, recombinant human IFN-gamma had no effect on suppressor function in patients with MS and in control subjects. This study shows that IFN-alpha and -beta augment deficient suppressor function in MS, whereas IFN-gamma has no effect on suppressor function in the progressive phase of the disease.

Biochemical and immunological responses of hairy cell leukemia patients to interferon beta

Ten hairy-cell leukemia patients were treated with interferon beta (IFN-beta) at a dose rate of 2 x 10(6) IU/m2 x 5 days for 4 weeks (induction therapy) and, thereafter, at the same dose three times a week for 11 months (maintenance therapy). The effect of this treatment on serum neopterin, beta 2-microglobulin, (2'-5')oligoadenylate [(2'-5')An] levels, intracellular (2'-5')An values and human Mx protein synthesis was analysed. There were significant rises in serum neopterin and (2'-5')An levels during both induction and maintenance, whereas beta 2-microglobulin levels rose only during induction. Rises in intracellular (2'-5')An were documented mainly during induction, but they were not significantly higher than pretherapy values. IFN beta provoked an increase in human Mx protein synthesis over the entire induction-maintenance period, but was only significantly higher than baseline during induction. All markers proved useful for monitoring the effects of IFN beta dose schedules, but were not predictive of clinical outcome. Natural killer activity and IFN gamma production, which were initially defective, followed a different trend from that of the other factors studied, in that increases were documented only late in the course of therapy when the disease was already in remission.

Intermittent interferonemia and interferon responses in multiple sclerosis

In view of the immunoregulatory and antiviral properties of the interferons (IFNs), the production of and response to these cytokines in vivo and in vitro were assessed in 42 patients with multiple sclerosis (MS), a disease with features of autoimmunity and a viral infection. Serum IFN, determined by bioassay of antiviral activity at 10 intervals over 18 months, was detectable at levels ranging from 16 to 250 IU/ml, at least once and up to five times in 37 of the 42 patients. Of 420 samples tested, 88 (21%) were positive. None of the 71 serum samples from 37 healthy subjects contained detectable IFN activity. Neutralization of antiviral activity by antibodies showed that the serum IFN type was IFN-alpha in 82 samples, IFN-gamma only in 2, and both IFN-alpha and IFN-gamma were present in 4. At the initial time point the activity of 2'-5' oligoadenylate synthetase (OAS), an IFN-induced enzyme, was elevated in peripheral blood leucocytes (PBL) from 13 patients, but not in 7 patients seropositive for IFN, indicating that in some patients there was a failure of PBL to respond to endogenous IFN. In most patients the capacity of PBL in vitro to produce IFNs-alpha/beta or -gamma after induction by virus or mitogens, respectively, was likewise reduced. These various abnormalities in IFN responses could not be correlated with clinical assessments of disease activity but may reflect subclinical attacks. The abnormalities described, in particular the intermittent interferonemia in MS, are more striking than in other diseases previously reported, indicating an unusual component to the stimulus for IFN production (viral or other) or the response to it. The effects of endogenous IFN production may have implications for the scheduling of therapy with IFN in MS.

Double blind study of intrathecal beta-interferon in multiple sclerosis: clinical and laboratory results

Sixteen patients with clinically definite MS admitted to a double blind randomised controlled trial of intrathecal natural beta-IFN were followed for a mean of 22 months including the six month treatment period. Clinical response, evaluated in terms of relapse frequency and of progression rate, showed an increase in relapse rate in treated patients during the six month treatment period and, overall, no benefit in treated versus placebo patients. Serial evaluations were made of cerebrospinal fluid (CSF) cells, IgG, myelin basic protein and CSF and blood T-cell subsets. A rise in CSF IgG Index, MBP and DR+ cells in IFN-treated patients suggested an activation of intrathecal immune response in treated patients.

PHA-induced interferon in multiple sclerosis: association between gamma interferon and clinical and genetical variables

Gamma interferon (INF-gamma) production, after PHA stimulation of peripheral blood mononuclear cells, from multiple sclerosis (MS) patients with the acute remitting and chronic progressive forms, in attack and remission phases, and from normal controls, was studied by immunoradiometric assay. MS patients in all these 4 clinical states of disease produced less INF-gamma (log value range from 2.55 to 2.65). MNC from the total MS patients produced significantly low levels of INF-gamma compared to the control group (log values 2.60 vs. 2.82; P = 0.001). No association between the interferon production and antigens at any HLA locus (A, B, C, Dw and Bf) was found. There was no correlation between IFN-gamma production and age, sex, duration of disease, or disability index. However there was a slight tendency to negative correlation with the progression index of the disease. The results suggest that this lower IFN-gamma production in MS may be secondary to the disease, and the primary defect may be a severe reduction of the essential lymphocyte populations required for an effective lymphokine cascade to produce the normal immune response against infection.

Expression of the genes of interferons and other cytokines in normal and diseased tissues of man

Specific interferon genes are transcribed at low levels in the spleen, liver, and peripheral blood leukocytes of normal individuals in the apparent absence of virus infection while other interferon genes remain unexpressed in the same tissues. In contrast, the genes of cytokines such as IL-1, IL-6 and TNF are expressed at relatively high levels in the organs of normal individuals. The level of expression of the IL-1, IL-6 and TNF genes is markedly reduced in the livers of patients with autoimmune liver disease compared to the level of expression in the liver of normal individuals, whereas the expression of interferon genes is similar in both normal and diseased liver, suggesting that a defect in the expression of specific cytokines is associated with severe liver disease.

Interferons and multiple sclerosis

Interferons (IFNs) are a family of proteins with antiviral, antitumoral and immunomodulating properties. Multiple Sclerosis (MS) is a CNS disease in which the immune reaction (IR) is the cause of the inflammatory demyelinating lesions. IFNs have been demonstrated in active lesions. The location of IFN gamma on astrocytes suggests an enhancing activity on IR by inducing Ia antigen expression on these cells. In contrast, IFN alpha/beta located on microglial cells and astrocytes might limit the growing lesion. MS patients frequently present a defective response of NK cell activity and an abnormally low production of IFNs reflecting immune dysregulation. The therapeutic trials available to date are discussed: IFN gamma possesses a severe deleterious effect but IFN alpha/beta are still under consideration due to a possible beneficial activity.

Natural killer (NK) cells in chronic progressive multiple sclerosis patients treated with lymphoblastoid interferon

Natural killer (NK) cell functional activity, as defined by the lysis of 51Cr-labelled K-562 cells, and number, defined phenotypically by anti-Leu-11, are significantly decreased in chronic progressive multiple sclerosis (MS) when compared to normal controls. When age- and sex-matched populations are compared, NK cell functional activity is again significantly reduced in MS compared to controls but not when compared to a control group of other medical disease (OMD). The MS group could be differentiated from the OMD group, however, when results of NK cell functional activity are combined with NK cell phenotype. With the administration of lymphoblastoid interferon daily for 6 months, NK cell activity increased significantly at 48 h and at 1 week. By 1 month, activity decreased to a level slightly above placebo treatment values. The results likely reflect interferon's enhancement of mature NK cell activity combined with a variable effect on recruitment of pre-NK cells.

Increased production of interferon gamma and tumor necrosis factor precedes clinical manifestation in multiple sclerosis: do cytokines trigger off exacerbations?

We have carried out a longitudinal study of interferon (IFN) and tumor necrosis factor (TNF) using a whole-blood mitogen stimulation assay in 20 multiple sclerosis (MS) patients and in a healthy control group. We set up individual profiles and the results were quite constant for each individual, both in healthy donors and in the patients in remission. Before exacerbations, however, we found an increase of IFN-gamma and TNF production preceding clinical symptoms by a maximum of 2 weeks. In benign cases, the increase disappeared rapidly, even before the appearance of symptoms, whereas we found sequelae whenever the increase persisted during weeks. In chronic progressive patients, we frequently found intervening increases. It may be that IFN-gamma and TNF trigger off exacerbations at a very early stage and that these cytokines may also play a role in maintaining disease in chronic progressive and invalidating forms.

Reduction of monocyte 5'nucleotidase activity by gamma-interferon in multiple sclerosis and autoimmune diseases

Ecto-5'nucleotidase (5'NT) activity in the plasma membrane of peripheral blood monocytes from patients with multiple sclerosis (MS), rheumatoid arthritis (RA), myasthenia gravis (MG), motor neuron disease (MND), and from normal control subjects of similar age was determined by radioisotopic assay. The activity in unstimulated monocytes cultured for 24 and 48 hours was found to be higher than normal in 56% of patients with active relapsing MS, 29% of patients with RA, and 7% of patients in the MG/MND group. While the enzyme activity was reduced after cultivation of the cells with recombinant interferon-gamma (gamma-IFN) in all of the groups studied, the percentage reduction was significantly greater in monocytes from patients with active relapsing MS who were in relapse at the time of sampling (p = 0.03). HLA-DR expression was monitored using immunofluorescence staining with monoclonal antibody and showed that similar numbers of monocytes in all patient and control groups expressed this antigen. Thus, while high monocyte 5'NT activity was found principally in patients with active relapsing MS and in some patients with RA, the monocytes from patients with MS were, in addition, exquisitely sensitive to stimulation with gamma-IFN.

Interferons and autoimmunity

Autoimmunity can be accelerated in several genetically prone murine models and can even be induced in normal mice by treatment with interferon (IFN) or IFN-inducers. Several cases of IFN-induced autoimmune disease in humans also have been observed; however, more striking is the fact that some of the clinical manifestations in autoimmune diseases and many of the immunological aberrations can be mediated or enhanced by IFN. The finding of high levels of circulating IFN in many patients may be highly significant in that respect, and the characterization of the predominant type of IFN as an unusual acid-labile IFN-alpha may indicate an infectious etiologic agent in autoimmunity, since this peculiar IFN was mostly associated with viral infections in vivo or in vitro. The induction of MHC class II antigens on previously HLA-DR or Ia negative cells appears to be caused primarily by IFN-gamma and may have a central role in the pathogenesis of autoimmunity in susceptible individuals. Such aberrant HLA-DR expression on nonlymphoid cells can be detected early in the disease in the target organs of many varied autoimmune conditions and may trigger a cascade of self-directed, uncontrolled immune response in conjunction with other factors.

Exacerbations of multiple sclerosis in patients treated with gamma interferon

In an open, randomised study, 18 patients with clinically definite, relapsing-remitting multiple sclerosis (MS) received 1 microgram, 30 micrograms, or 1000 micrograms doses of recombinant gamma interferon (IFN-gamma), given by intravenous infusion twice a week for four weeks. 7 patients had exacerbations during treatment. This exacerbation rate, compared retrospectively with the pretreatment rate and prospectively with the post-treatment rate, was significantly greater than expected. Exacerbations were not precipitated by fever or other dose-dependent side-effects. A concomitant increase in circulating monocytes bearing class II (HLA-DR) surface antigen suggested that the attacks induced during treatment were immunologically mediated. IFN-gamma is unsuitable for treatment of MS.

NK activity and NK-like non-specific cytolysis after PPD, rubella and measles antigen stimulation in multiple sclerosis

Blood samples were collected from 14 pairs of multiple sclerosis (MS) patients and from age- and sex-matched healthy controls. The cytotoxic activity of peripheral blood mononuclear cells was tested against the K562 cell line on the day of collection and again after 3 days in vitro culture with medium or with purified protein derivative of tuberculin (PPD), inactivated rubella virus or inactivated measles virus antigen. Lymphocytes from MS patients had a lower spontaneous cytotoxic activity compared to the controls both on the day of collection (P less than 0.025) and after 3 days in culture with medium alone (P less than 0.025). The activity decreased during in vitro culture in both groups, but the decrease was greater among MS patients (P less than 0.05). In cultures with antigens, a strong increase of NK-like cell-mediated cytolysis (NK-like CMC) was noted especially in cultures stimulated with PPD. There were no significant differences in the increase of the activity among MS patients and control subjects. A significant correlation between the increase of NK-like CMC and the lymphocyte blast transformation response induced by each antigen was found.

Interferon induction, 2'-5' oligo A synthetase and lymphocyte subpopulations in out-patients with multiple sclerosis in a longitudinal study

Nine patients with multiple sclerosis, four with relapsing-remitting disease, and five with chronic progressive disease, together with eight healthy control, were followed for nearly a year with monthly clinical and laboratory examinations. Alpha- and gamma-interferon was induced in lymphocytes with different viruses and PHA, no differences were found between healthy controls and multiple sclerosis patients. The alpha- and gamma-interferon induced enzyme 2'-5' oligo A synthetase in lymphocytes was found to have a tendency to be lower in multiple sclerosis patients than in healthy controls. When medians of ratios of helper/suppressor blood lymphocytes in multiple sclerosis patients were compared with healthy controls, the same results were found, although higher values of ratios were found among the patients and the highest value was found in a patient with chronic progressive disease. No correlation to disease activity could be found in interferon inductions, 2'-5' oligo A synthetase concentrations and ratios of OKT4/OKT8. In particular no change in ratio was found in relation to five exacerbations taking place in the four multiple sclerosis patients with acute relapses.

Lymphocytes from multiple sclerosis patients produce elevated levels of gamma interferon in vitro

The production of gamma interferon (IFN) by mononuclear cells (MNC) from patients with exacerbating/remitting multiple sclerosis (MS) and controls was evaluated. After 3 days of culture with concanavalin A, the amount of gamma IFN in supernatant fluids was determined by radioimmunoassay. MNC from MS patients produced significantly (P less than 0.001) more gamma IFN than MNC from either normal controls or patients with other neurologic diseases. Levels of gamma IFN in the serum and CSF were also measured. Despite the relative absence of gamma IFN in serum (4 positive of 30), all CSF samples tested had low, but detectable, levels of gamma IFN (0.3 to 1.4 U/ml). These studies suggest that some of the autoimmune features and immunologic abnormalities in MS may be related to elevated gamma IFN production.

Natural killer cell activity in multiple sclerosis and myasthenia gravis

Because of the potential role of Natural Killer (NK) cells in viral immunity and immunoregulation, we have undertaken a study of NK activity of peripheral blood lymphocytes from both Multiple Sclerosis (MS) and Myasthenia Gravis (MG) patients, two chronic diseases in which a viral etiology and an induced autoregulatory abnormality are strongly implicated. No significant difference between the mean NK activity in MS patients and controls was observed. A difference was observed between the NK activity of female MG patients and female controls, but no difference was seen between male MG patients and controls.

Leukocytes from multiple sclerosis patients respond to alpha- and gamma-interferons

Blood mononuclear leukocytes from multiple sclerosis (MS) patients were evaluated for reactivity to alpha- or gamma-interferon (IFN), using a response whereby IFN-treated (primed) cells synthesize higher levels of IFN than untreated cells. Leukocytes were treated in vitro with natural alpha-IFN, recombinant alpha-IFN, recombinant gamma-IFN, or no IFN, then exposed to measles virus to induce IFN synthesis. With no IFN treatment, IFN production by cells from the MS patients was significantly less than normal (P less than or equal to 0.025). However, with IFN treatment, cells from MS patients were primed as well as cells from normal controls: IFN synthesis for the MS patients' cells was increased 10-11-fold with either alpha-IFN preparation and 3.6-fold with gamma-IFN. These findings verify the presence of leukocyte reactivity to alpha-IFN and provide the first demonstration of responsiveness to gamma-IFN in MS.

Influence of prostaglandin E2 and indomethacin on interferon-gamma production by cultured peripheral blood leukocytes of multiple sclerosis patients and healthy donors

The addition of indomethacin to concanavalin A (Con A)-induced cultures of human peripheral blood leukocytes (PBL) caused an increase in interferon response, regardless of whether the PBLs were derived from multiple sclerosis (MS) patients or from control donors. Specifically the response rates increased from 71 to 100% in controls and from 24 to 53% in MS patient-derived cultures. The amounts of interferon produced also increased in both groups by 0.8 log U/ml. However, interferon yields of nonresponsive cultures becoming interferon-producing only after indomethacin treatment remained relatively low. In control cultures, maximal increases of interferon production were obtained with doses of 0.05 to 0.1 microgram/ml indomethacin; for MS patients higher doses were needed--0.1 to 0.5 microgram/ml. Conversely, a relatively low dose (0.05 microgram/ml) of exogenous prostaglandin E2 (PGE2) was able to inhibit interferon production completely in MS patient-derived cultures, whereas in control cultures higher doses were needed (0.1 to 1.0 microgram/ml). Analysis of endogenous PGE2 levels in the PBL cultures revealed that PGE2 production was similar in nonresponder MS cultures and responder control cultures but that MS leukocytes were more sensitive to the inhibitory effect of PGE2 on interferon production. We conclude that in a minor percentage of MS patient-derived PBL cultures, the deficiency in interferon-gamma (IFN-gamma) production can be (partially) overcome by treatment of the cells with indomethacin. However, in the major part of nonresponder MS cultures, indomethacin has no effect, indicating that the PG system is not the major cause for the defective interferon response in MS.

Studies of interferon production and natural killing by lymphocytes from multiple sclerosis patients

Peripheral blood lymphocytes from patients with multiple sclerosis (MS) have been shown by numerous investigators to function abnormally in a variety of immunological tests in vitro. In this article, data concerning defective natural killer (NK) cell function and interferon production by MS patients' lymphocytes have been reviewed. Production of IFN-alpha and IFN-gamma by appropriately stimulated lymphocytes has been shown to be significantly reduced in many patients with acute remitting or chronic progressive disease. Furthermore, a significant proportion of these patients has been found to exhibit reduced levels of endogenous and augmented NK cell activity. A likely explanation for these phenomena is that altered traffic occurring as a consequence of disease has led to a relative loss of NK and IFN-producing cells from the peripheral circulation. Flow cytometric data obtained using monoclonal antibodies that selectively label these effector populations were presented. Possible explanations for the observed defects and their significance relative to our understanding of the etiopathogenesis of MS were discussed.

Cytotoxic activity of peripheral blood and cerebrospinal fluid lymphocytes from patients with multiple sclerosis and other neurological diseases: analysis at the single cell level of the relationship of cytotoxic effectors and interferon-producing cells

The production of interferon (IFN alpha) in relationship to NK and ADCC activity of peripheral blood and cerebrospinal lymphocytes was examined at the single cell level in patients with multiple sclerosis (MS) and other neurological diseases (OND) compared with age- and sex-matched controls. IFN-producing cells were assessed by indirect immunofluorescent scoring of cytoplasmic IFN+ cells. Peak production of cytoplasmic IFN alpha in nylon wool-passed ( NWP ) cells occurred between 5 and 17 hr in vitro under the inductive stimulus of MOLT 4, K562, or antibody-coated Chang liver cells. The proportion of K562- and MOLT 4-induced IFN alpha-positive cells in the total lymphocyte and target-binding cell (TBC) population was significantly lower in MS NWP -peripheral blood lymphocytes (PBL) than in OND and normal controls; this was in direct relationship to a decreased percentage of NK cells in MS PBL. In contrast MS cells responded the same as controls (total IFN+ cells) or higher than controls (IFN+-TBC) after IFN alpha induction by antibody-coated Chang, the ADCC target, in parallel with elevated ADCC activity by MS PBL. MS CSF contained a higher proportion of total IFN+ cells but a similar proportion of IFN+-TBC as their homologous NWP PBL population. In OND CSF, both the percentage of total IFN+ and the percentage of IFN+-TBC were higher than in OND blood and higher than their respective MS CSF populations. The relationship of IFN-producing cells in the central nervous system (CNS) to putative cytotoxic cells is discussed.

Leukocyte surface antigens in patients with multiple sclerosis

Lymphocyte phenotypes have been measured in 20 normal females, 19 normal males, 3 females with acute exacerbations of MS and 21 females and 17 males with chronic progressive MS. Using a FACS IV, lymphocytes were gated by light scattering properties, and fluorescence was analyzed using a log amplifier. No abnormalities were found in the 3 females with acute exacerbations. In male patients the percentage of OKT8 was significantly reduced, the percentage of OKT4 was significantly increased, and the ratio of OKT4/T8 was increased. In females with chronic progressive disease the percentage of OKT8 was not statistically altered, but the percentage of OKT4 and the OKT4/T8 ratio were elevated. Interpretation of these findings requires more extensive study in control populations.

Decreased interferon synthesis and responsiveness to interferon by leukocytes from multiple sclerosis patients given natural alpha interferon

Despite the use of interferon (IFN) in numerous clinical trials, relatively little is known about how IFN therapy influences leukocyte function. To evaluate some of its effects, leukocytes from multiple sclerosis (MS) patients given daily treatments of natural alpha IFN (IFN-alpha) were evaluated for IFN synthesis and two responses to IFN in vitro: enhancement (priming) of IFN synthesis and suppression of Concanavalin A (Con A)-induced T-cell mitogenesis. The IFN therapy had no effect on the sensitivity of Con A-stimulated leukocytes to the antiproliferative action of IFN-alpha. However, using Newcastle disease virus (NDV), measles virus, or poly I:C to stimulate IFN synthesis, cells from IFN-treated patients produced less IFN in response to all inducers, with titers ranging between 11% and 44% of pretherapy values. Also, unlike cells from these same patients before therapy or from the placebo recipients, cells from the IFN recipients were not primed by either IFN-alpha or -beta even though IFN-beta had not been used for therapy. The loss of these priming reactivities suggests that resistance to IFN had developed in IFN-treated patients.

Immunological treatment of multiple sclerosis

Immunosuppressive treatment of multiple sclerosis (MS) is based on the autoimmune hypothesis for which the main evidence is the close histological similarity between the human disease and chronic relapsing EAE. Although controlled trials indicate that ACTH is effective in accelerating recovery from relapses, long term ACTH or oral steroids are ineffective. Two controlled trials have suggested a beneficial effect of azathioprine, but neither was conducted "blind" and neither was sufficiently convincing to cause the widespread adoption of azathioprine by neurologists. One controlled trial, also not blind, reported a beneficial effect of an intensive course of cyclophosphamide, but this hazardous treatment will not be widely adopted unless other trials confirm this result. The converse hypothesis that MS is due to a deficient immune response to a virus has led to trials of immunostimulation. Interferon and levamisole have proven ineffective so far, but transfer factor slowed disease progression in one well conducted trial.