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Development of neuroprotective therapies for multiple sclerosis is dependent on defining the precise mechanisms whereby immune effector cells and molecules are able to induce relatively selective injury of oligodendrocytes (OLs) and their myelin membranes. The selectivity of this injury could be conferred either by the properties of the effectors or the targets. The former would involve antigen specific recognition by either antibody or T cell receptor of the adaptive immune system. OLs are also susceptible to non antigen restricted injury mediated by components of the innate immune system including macrophages/microglia and NK cells. Target related selectivity could reflect the expression of death inducing surface receptors (such as Fas or TNFR-1) required for interaction with effector mediators and subsequent intracellular signaling pathways, including the caspase cascade. Development of therapeutic delivery systems, which would reach the site of disease activity within the CNS, will permit the administration of inhibitors either of the cell death pathway or of effector target interaction and opens new avenues to neuroprotection approach.

We have previously reported that neonatal rat oligodendrocytes (OLGs) express and secrete neuregulins (NRGs) (Raabe et al., 1997). This laboratory has also shown that NRGs stimulate the differentiation of neonatal rat OLGs and that these cells express the erbB receptors for NRGs (Raabe et al., 1997). In this study, we have characterized NRG expression in adult human OLG cultures isolated from the temporal lobe resection of intractable epilepsy patients. Using immunocytochemistry and Western blotting, we find that adult human OLGs contain both the alpha and beta isoforms of NRGs. In addition, Western blots show that the adult human OLGs secrete both isoforms as N-glycosylated molecules. These cells also express all four erbB receptor subtypes, and possibly an activated erbB receptor. The observation that these cells synthesize and secrete their own NRGs, and possibly express a tyrosine-phosphorylated erbB receptor, is consistent with autocrine and/or paracrine signaling. Amplification of this signaling may provide a useful mechanism to stimulate differentiation of adult human OLGs in demyelinating disease.

We assessed the immune response induced in multiple sclerosis (MS) patients who had received NBI-5788, an altered peptide ligand (APL) designed from an immunodominant region (83-99) of the neuroantigen myelin basic protein (MBP) (5, 10, or 20 mg subcutaneously weekly for 4 weeks). The mean frequency of NBI-5788-responsive T cells (stimulation index3) in MS patients treated with the APL was 35.8 +/- 12.8% (n = 7) compared with a mean frequency of 6.2 +/- 1.3% (n = 7) for the untreated patients. The mean frequency of whole MBP-responsive T cells in MS patients treated with the APL was not significantly different from that of untreated patients (16.4 +/- 5.7% vs 18.0 +/- 6.3%, respectively). NBI-5788-reactive T-cell lines generated from NBI-5788-treated patients exhibited an increased frequency of cross-reactivity with MBP peptide 83-99 compared with NBI-5788-reactive lines from control MS patients. Cytokine secretion by APL-reactive T-cell lines from NBI-5788-treated MS patients was more frequently T-helper 2-like compared with T-cell lines from untreated MS patients. These results demonstrate that subcutaneous administration of a soluble APL based on the MBP peptide 83-99 in MS patients can induce an APL-reactive immune response in which T lymphocytes cross-reactive with the immunodominant neuroantigen MBP secrete anti-inflammatory cytokines. The significant heterogeneity in immune response between individuals indicates the need for clinical laboratory correlation during the course of therapeutic trials.

We found that in vitro migration and interferon-gamma production by lymphocytes derived from primary progressive multiple sclerosis patients preselected on the basis of a high T2-weighted lesion volume (10 cm3) on magnetic resonance imaging, were increased compared with that in primary progressive multiple sclerosis patients with a low T2-weighted lesion volume (3 cm3) and controls. Whether the heterogeneity of immune function within the primary progressive population will correlate with response to therapy remains to be established.

Previous reports by our group and by others have shown that in vitro treatment of T cells derived from healthy, normal subjects with interferon beta-1b (IFN-beta1b) reduces metalloproteinase (metalloproteinase type 9 [MMP-9]) activity with a consequent reduction in lymphocyte migration. In this study, we used a Boyden chamber assay to assess the migratory capacity of T cells derived from multiple sclerosis patients who either did or did not receive IFN-beta1b. Lymphocytes derived from patients treated for less than 2 years with IFN-beta migrated at a low rate that was indistinguishable from that of cells isolated from healthy donors. However, longer term treatment with IFN (3.5 years) was associated with a reversion of the migration to a high level that did not differ statistically from that of cells isolated from untreated multiple sclerosis patients. For both high-migratory groups, migration could be reduced to control levels after the exogenous addition of TIMP-1, a relatively specific inhibitor of the MMP-9, implicating this protease in the process of T-cell migration. Our findings suggest that one of the mechanisms by which IFN-beta exerts its action is by reducing MMP-9 activity and thus the entry of inflammatory cells into the nervous system and, as such, MMPs may constitute potential therapeutic targets in inflammatory diseases such as multiple sclerosis.

Interferon-gamma (IFN-gamma) is implicated as a participant in the immune effector and regulatory mechanisms considered to mediate the pathogenesis of multiple sclerosis (MS). We have used an intracellular cytokine staining technique to demonstrate that the proportion of ex vivo peripheral blood CD4 and CD8 T-cell subsets expressing IFN-gamma is increased in secondary progressing (SP) MS patients, whereas the values in untreated relapsing-remitting (RR) MS patients are reduced compared with those of controls. Patients treated with interferon-beta (IFN-beta) have an even more significant reduction in the percentage of IFN-gamma-secreting cells. The finding that the number of IFN-gamma-expressing CD8 cells is increased in SPMS patients, a group with reduced functional suppressor activity, and is most significantly reduced by IFN-beta therapy, which increases suppressor activity, indicates that IFN-gamma secretion by CD8 T cells and functional suppressor defects attributed to this cell subset in MS can be dissociated.

Activated glial cells are implicated in regulating and effecting the immune response that occurs within the CNS as part of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). The peripheral benzodiazepine receptor (PBR) is expressed in glial cells. We examined the utility of using in vitro and in vivo ligand binding to the PBR as a measure of lesion activity in autoimmune CNS demyelinating diseases. Applying a combined autoradiography and immunohistochemical approach to spinal cord and brain tissues from mice with EAE, we found a correlation at sites of inflammatory lesions between [3H]-PK11195 binding and immunoreactivity for the activated microglial/macrophage marker Mac-1/CD11b. In MS tissues, [3H]-PK11195 binding correlated with sites of immunoreactivity for the microglial/macrophage marker CD68, at the edges of chronic active plaques. Positron emission tomography (PET) imaging with [11C]-PK11195 showed ligand uptake only at sites of active MS lesions defined by magnetic resonance imaging criteria. Our results indicate the potential to develop markers suitable for both in vitro and in vivo use, which will serve to help correlate phenotypic and functional properties of cells which participate in disease or injury responses within the CNS.

gamma delta T-cells are found in increased proportion in multiple sclerosis (MS) white matter plaque infiltrates compared with peripheral blood or spleen, raising the possibility that they are either specifically attracted to lesion sites or, once present, are stimulated to expand. We have previously shown that human oligodendrocytes (OGC) preferentially express heat shock proteins (hsp), molecules to which gamma delta T-cells have been known to react and that in vitro expanded gamma delta T-cells can lyse OGC. We therefore investigated whether human glial cells, that differentially express hsp, could stimulate gamma delta T-cell expansion from peripheral blood. We compared the glial cell-induced expansion to cell lines which also differentially express hsp and have been shown to selectively stimulate gamma delta T-cell expansion (e.g. RPMI 8226, Daudi). We found that both OGC and human fetal astrocytes (hFA) expressed hsp and stimulated the preferential expansion of gamma delta T-cells to about the same extent as the hsp expressing cell lines RPMI 8226 or Daudi, in the presence of exogenous interleukin-2 (IL-2) but without any T-cell mitogen. Furthermore, the type of gamma delta T-cells expanded were of the V delta 2 subtype known to be particularly reactive to hsp. Microglia, U937 cell lines or purified myelin membranes, which express little or no hsp, did not support gamma delta T-cell growth. These results therefore suggest that OGC may contribute to the local expansion of gamma delta T-cells within MS plaques. Potential harmful effects of gamma delta T-cells on OGC may thereby contribute to the immunopathogenesis of MS demyelination.

In multiple sclerosis (MS), the influx of activated T lymphocytes into the brain parenchyma leads to the subsequent damage of oligodendrocytes, the cells that produce central nervous system (CNS) myelin. We report here that interferon beta-1b (IFNbeta-1b), a drug shown to be efficacious in the treatment of patients with MS, decreases the in vitro migration of activated T lymphocytes through fibronectin (FN), a major component of the basement membrane that surrounds cerebral endothelium. At 1,000 IU/ml, IFNbeta-1b reduced the migratory rate to that of unactivated T cells. In contrast, IFNgamma at 1,000 IU/ml, which caused a similar decrease (25%) in the proliferation rate of T lymphocytes as IFNbeta-1b, did not affect migration. All T-lymphocyte subsets and natural killer (NK) cells were demonstrated by flow cytometry to be equally affected by IFNbeta-1b treatment. 125I-Western blot analyses revealed that IFNbeta-1b treatment resulted in a marked reduction of the ability of T cells to cleave FN. The substrate-degrading capability of T lymphocytes was shown to be due predominantly to the activity of a 92-kd matrix metalloproteinase, MMP-9, whose levels were decreased by IFNbeta-1b. We suggest that the clinical benefits of IFNbeta-1b treatment in MS patients may be in part a result of the ability of this drug to significantly decrease MMP-9 activity, leading to a reduction of T-lymphocyte infiltration into the CNS.

Microglial cells are resident cells of the CNS and are implicated as regulators and effectors of immune responses which occur within this compartment. The precise role of parenchymal microglia remains speculative because distinctions between these cells, perivascular "microglia," and blood-derived monocytes/macrophages are not well defined. The current study describes the phenotype and function of microglia immediately upon isolation from the non-inflamed adult human CNS and the phenotypic changes which occur in these cells when maintained in tissue culture. We find that the characteristic phenotype of immediately ex vivo parenchymal microglia (CD11c+/CD45low/CD14) corresponds to that found in situ in the "normal" human brain. The phenotype differs from that of perivascular "microglia" in situ and PBDM (both CD45hi/CD14++). The immediately ex vivo microglia express B7-2 and HLA class II molecules and can support alloantigen-induced proliferation by CD4+ T cells freshly isolated from peripheral blood. Following in vitro culture, the cells are characterized by a bipolar morphology, continued lower levels of CD45 expression compared to PBDM, and slight upregulation of B7-1 and HLA-DR antigen expression. CD14 becomes expressed at high levels on the cells, suggesting that CD14 can serve as an apparent marker of microglia activation which is not based on changes in morphology or APC capacity. Further, treatment of the cells with IFN-gamma and LPS causes further upregulation of HLA-DR and clear expression of B7-1 molecules on the surface. The capacity to characterize phenotypic and functional properties of microglia before and after activation provides an opportunity to determine means to manipulate the immune regulatory and effector properties of this cell type.

Microglial cells function as regulators of immune reactivity within the CNS and may contribute to tissue injury under inflammatory conditions. Such functions are correlated with their state of activation. In this study, we report the de novo expression of CD14 by adult human CNS-derived microglia which acquire a bipolar activated morphologic phenotype in dissociated tissue culture. Surface CD14 expression can be down-regulated by interaction with its ligand lipopolysaccharide (LPS), and by the T-helper (Th1) cytokine interferon-gamma (IFN-gamma) or the Th2 cytokine interleukin-4 (IL-4). Semiquantitative polymerase chain reaction (PCR) analysis of CD14 mRNA expression under each condition suggests a different mechanism accounting for the reduced surface expression. LPS down-regulates CD14 mRNA, consistent with a feed-back signal preventing over-stimulation. IFN-gamma augments CD14 transcription, suggesting cleavage of surface CD14 consequent to general cell activation. IL-4 decreases mRNA production likely reflecting a generalized suppressive effect. The effect of LPS, IFN-gamma and IL-4 on CD14 expression differes from their effect on expression of the immune-accessory molecules B7-1 and HLA-DR, and on production of tumor necrosis factor-alpha (TNF-alpha), whose secretory pathway is similar to that of CD14. These results indicate the selective effects of molecules, likely to be present in the infected or inflamed CNS, on regulating CD14 expression and that there can be differential regulation of immune response relevant molecules expressed by activated microglia.

Oligodendrocytes (OLs) and their myelin membranes are the apparent injury targets in the putative human autoimmune disease multiple sclerosis. The basis for this selective injury remains to be defined. OLs in vitro have been shown to be susceptible to both tumor necrosis factor (TNF) and non-TNF-dependent immune effector mechanisms. The former involves initial nuclear injury (apoptosis); the latter, when mediated by activated T cells, involves initial cell membrane injury (lysis). In the current study, we determined whether human adult CNS-derived OLs could be protected from the above immune effector mechanisms by selected neurotrophic factors (CNTF, BDNF, NGF, NT-3, and NT-4/5) or cytokines demonstrated to protect from human or experimental autoimmune demyelinating diseases (beta-interferon [IFN], IL-10, and TGF-beta). Nuclear injury was assessed in terms of DNA fragmentation using a DNA nick-end-labelling technique; cell membrane injury was assessed by lactate dehydrogenase or chromium 51 release. MTT and cell counting assays were used to assess cell viability and cell loss, respectively. Amongst the neurotrophic factors and cytokines tested, only CNTF significantly protected the OLs from TNF-mediated injury. CNTF also protected the OLs from serum deprivation-induced apoptosis. CNTF, however, did not protect the OLs from injury induced by activated CD4+ T cells. CNTF also did not protect human fetal cortical neurons from serum deprivation or TNF-induced DNA fragmentation, nor did it protect the U251 human glioma cell line from DNA fragmentation induced by a combination of TNF and reduced serum concentration in the culture media. Our results indicate that potential protective effects of neurotrophic factors or cytokines on neural cell populations can be selective both for cell type involved and mechanism of immune-mediated injury. CNTF is the protective factor selective for nuclear-directed injury of OLs.

Systemic interferon-beta-Ib (IFN-beta-Ib) reduces the frequency of clinical exacerbations and the number of magnetic resonance imaging (MRI)-defined lesions in patients with relapsing-remitting MS. The basis for this clinical effect is not understood. While IFN-beta-Ib has been demonstrated to have antiproliferative and immunomodulatory effects on the systemic immune system, its actions on neural cells could also contribute to its therapeutic efficacy. In this study, we have examined possible immune and non-immune effects of IFN-beta-Ib on CNS-derived primary human cells. With respect to immune-related effects, application of IFN-beta-Ib did not decrease basal expression of HLA-DR on astrocytes or microglia, and it reduced the IFN-gamma-enhanced HLA-DR expression on adult human astrocytes only at high concentrations (1000 IU ml-1); IFN-beta-Ib at all concentrations tested did not reduce the IFN-gamma-enhanced HLA-DR expression by fetal astrocytes or adult microglial cells. In contrast, but in correspondence with the literature, the IFN-gamma-enhanced HLA-DR expression on a glioma cell line was attenuated by IFN-beta-Ib in a dose-dependent manner. With respect to non-immune effects, the number of adult human oligodendrocytes and their state of morphological differentiation were not affected by IFN-beta-Ib. Proliferation of the mitotically active fetal human astrocytes, however, was reduced by IFN-beta-Ib treatment. Lactate dehydrogenase assays revealed that IFN-beta-Ib was not toxic to neural cells, including adult oligodendrocytes and fetal human neurons. We conclude that IFN-beta-Ib lacks efficacy in down-regulating HLA-DR expression by primary human neural cells and that regulation of MHC class II antigens is unlikely to be a mechanism for its beneficial effect in MS. Finally, the lack of toxicity of IFN-beta-Ib on human neural cells is important for a drug that will probably be used widely.

We performed a longitudinal analysis of serum interleukin-2 (IL-2) and soluble IL-2 (sIL-2R) concentrations in 60 patients with relapsing-remitting (R-R) multiple sclerosis (MS) as well as in 33 age- and sex-matched normal controls. Overall, we found that serum IL-2 levels remained low (less than 10 U/ml) and did not change appreciably over time; however, marked fluctuations in sIL-2R levels were observed in both the patient and control groups. Using patients as their own controls, we calculated an interrelapse (disease stable) mean sIL-2R concentration as a baseline for comparison with relapse values; sIL-2R levels greater than the 90th percentile of the Student's t distribution of stable values were defined as "peaks." There were a total of 27 sIL-2R peaks, eight (30%) of which correlated with clinical relapses but were potentially predictive of only 18% (8/45) of all the recorded clinical relapses. There was no difference in disease severity (Expanded Disability Status Scale) score between peak-correlated and noncorrelated relapses. Our data suggest that despite reports of elevated levels of IL-2 and sIL-2R in MS, neither may be a useful marker for predicting clinical disease activity in R-R MS.

T cells are postulated to contribute to the injury of the oligodendrocyte-myelin complex underlying the demyelinating disease multiple sclerosis (MS). The apparent lack of class I or II major histocompatibility complex (MHC) expression in situ on human oligodendrocytes and the consistent failure to identify a universal myelin antigen in MS suggest that the immune damage might be mediated by effector T cells that are capable of reacting in an antigen-nonspecific and possibly MHC-unrestricted manner, such as T cells expressing the gamma-delta T-cell receptor. Since gamma-delta T cells are reported to be present in MS plaques and an increased number are found in the cerebrospinal fluid of patients with MS, we directly examined whether gamma-delta T cells are capable of inducing injury to human oligodendrocytes. We found, using a 6-hour 51Cr release assay, that oligodendrocytes cultured from surgically resected human brain specimens were effectively lysed in a dose-dependent manner by human gamma-delta T cells (28 +/- 5% mean specific lysis, n = 6, at an effector-target ratio of 20:1). Although heat shock protein HSP72, a putative gamma-delta T-cell recognition molecule, could be induced in vitro in our oligodendrocytes, an antibody to HSP72 did not inhibit gamma-delta T cell-mediated lysis of oligodendrocytes. These results suggest that gamma-delta T cells gaining entry into the central nervous system may be deleterious to oligodendrocytes and thus may contribute to the pathogenesis of MS.

In order to examine questions concerning immunologic privilege of the central nervous system, we placed neocortical transplants into cerebral ventricles of mice. We compared the fates of transplants between fully H-2 compatible (isografts) and H-2 incompatible (allografts) animals. Histologic evaluation comparing animals from iso- and allograft groups revealed significant differences in the number of inflammatory cells and in the degree of necrosis within the grafts. Response to allografted tissue within the brain mimics that seen in several immune-mediated diseases of the nervous system in that neurons appear to be selectively spared. Only upon subsequent stimulation of the host's immune system with an orthotopic skin graft bearing the major histocompatibility complex antigens of the neural graft are neurons destroyed. Immunohistochemical evaluation revealed that the inflammatory cell infiltrates in and around the allografts were composed of Lyt-2+, L3T4+, and Mac-1+ cells. In addition, Ia+ endothelial cells as well as Ia+ parenchymal CNS cells were found in both donor and host tissue of allografted animals. Hence, H-2 incompatible neural tissue transplanted to the CNS is recognized and rejected by the immune system of the recipient animal. The cellular infiltrates seen within the first weeks to months following transplantation of allogeneic CNS tissue resemble those seen in other allografts undergoing rejection. We conclude that the CNS is not unconditionally privileged as either a transplant site or as a source of transplanted tissue.

We measured the pokeweed mitogen (PWM)-induced secretion of IgG by the unfractionated mononuclear cells (MNC) of young adult donors, and correlated the results with the functional activity of cell suspensions enriched for T helper (T4+) and T suppressor/cytotoxic (T8+) cells. The distribution of IgG levels secreted by MNC differs from a Gaussian curve, implying that the group is composed of distinct heterogeneous populations. When donors were compared who were judged to be very low responders or very high responders on the basis of IgG secretion levels by MNC (less than 700 ng/ml or greater than 2500 ng/ml), no differences were found in the capacity of T4+-enriched cells to support PWM-driven IgG secretion by a common B cell pool. In contrast, the addition of 0.2 X 10(5) T8+ cells from these low responders to PWM-stimulated cultures of 0.5 X 10(5) T4+ cells plus 0.5 X 10(5) B cells resulted in significantly less IgG secretion (389 +/- 121 ng/ml) than did the addition of the same number of T8+ cells from the high responders (2241 +/- 548 ng/ml, p less than 0.01). Normalized percent suppression by T8+ cells was higher in low responders than in high responders (77.0 +/- 9.9% vs 33.0 +/- 8.5%, p less than 0.01). Both high and low responders markedly suppressed IgG secretion when 0.5 X 10(5) T8+ cells were added. No correlation was found either between proportion of T3+, T8+, T4+, or M1+ cells within the MNC population and levels of IgG secretion by MNC or between T8+ numbers and levels of suppression induced by a constant number of T8+-enriched cells. Our data indicate that differences in the functional activity of T8+ cells, rather than quantitative differences, account for the wide range of PWM-induced IgG secretion by MNC.

Concanavalin A (Con A)-induced suppressor activity has previously been shown to be reduced in multiple sclerosis (MS) patients with active clinical disease. In this study, we demonstrate that OKT3, as well as Con A induced suppressor activity mediated by unfractionated peripheral blood mononuclear cells is reduced in patients with the progressive form of MS. By performing reconstitution experiments involving E+, T4+, or T8+ cells derived from either MS patients or controls, and normal allogeneic macrophages or E- cells, we sought to define the cellular basis for this suppressor defect. In both MS and control groups, E+ cells were required to obtain measurable levels of suppression. Suppressor levels induced by Con A-activated cultures containing E+ cells from MS patients were lower than those induced by those containing control donor E+ cells. Suppression mediated by T8+ cells from MS patients was also lower than for controls. In the control group, suppression mediated by T8+ cells exceeded that mediated by T4+ cells; such differences were not apparent in the MS group. These results suggest that although Con A-induced suppression can be mediated by a number of T and non-T cell subsets, the functional suppressor defect measured in the MS population does involve the T8+ cell subset.

Cell-mediated immune mechanisms contribute to tissue injury within the central nervous system (CNS) in a number of experimental diseases, including experimental allergic encephalomyelitis and some viral infections, and may mediate lesion formation in multiple sclerosis. We investigated the conditions under which murine astrocytes can become susceptible targets of cytotoxic T cells. We demonstrate that mouse astrocytes in vitro can be susceptible targets of class I major histocompatibility complex (MHC)-specific cytotoxicity mediated by L3 cytotoxic T lymphocytes (CTL). Expression of appropriate class I MHC antigen on the astrocytes is a requirement, because only cells bearing the H-2d phenotype are susceptible to lysis by L3 cells. BALB/c-H-2dm2 astrocytes lacking the specific determinant recognized by L3 cells are not susceptible to lysis. Astrocyte lysis can, however, occur under culture conditions in which MHC antigen expression is immunocytochemically low or undetectable. Cytolysis can be inhibited by pretreatment of the effector L3 cells with either anti-Lyt-2 monoclonal antibody (mAb) or anti-clonotypic mAb and by preincubation of the glial target cells with an appropriate anti-H-2 antibody (anti-H-2Ld). mAb to lymphocyte function-associated antigen does not inhibit cytotoxicity of the L3 clone against glial cells. Knowledge regarding the role of CTL within the CNS, including the surface molecules involved in glial cell lysis, could further the development of immunotherapies designed to effect immune reactivity within the CNS.

Within the clinical spectrum of MS, emphasis is on variations, factors influencing the clinical course, and differential diagnosis and treatment, with a highlight on selection of appropriate patients for "experimental" therapies.

A patient with partial deficiency of N-acetyl-beta-hexosaminidase (Hex) developed a progressive motor neuron syndrome beginning at age 7, characterized by dysarthria, muscle wasting, fasciculations, and pyramidal tract dysfunction. Minor clinical features have included tremor and late distal sensory abnormalities. Rectal biopsy at age 24 demonstrated membranous cytoplasmic bodies in submucosal ganglion cells. Biochemical evaluation revealed nearly absent Hex B activity in serum, leukocytes, and fibroblasts, with partial Hex A activity in serum and leukocytes, and low normal Hex A activity in fibroblasts. Motor neuron disease can be a presentation of a Hex beta locus defect, in addition to the previously recognized Hex alpha locus defects.

Evidence points to the conclusion that abnormal regulation of the immune response in MS contributes to ongoing immune activity.

Multiple sclerosis (MS) is characterized by a relapsing and remitting course, particularly in the early phases of the disease. Tests of immune function conducted both on peripheral blood and spinal fluid strongly suggest that aberrant immune function occurs in MS patients. These aberrancies appear to be most striking during periods of active disease, although they may at times remain detectable during periods of clinical quiescence. For example, in studies of sensitivity of peripheral blood or cerebrospinal fluid (CSF) lymphocytes to myelin antigens, the most striking changes have been reported in patients with active disease. Similarly, changes in the percent of B and/or T cells in peripheral blood have been most evident when disease is active. Oger et al. [14] in contrast, have found that depressed numbers of avid T cells, probably representing a T-cell subset, are observed both when disease is active and when it is quiescent. Noronha et al. [13] have presented evidence that CSF lymphocytes of MS patients remain activated as measured by RNA/DNA content, even during seemingly quiescent disease. The possibility that MS is seldom “burned out” must be seriously entertained.

A set of observations made on a patient with IgM lambda monoclonal gammopathy and neuropathy implicate humoral immunity in the pathogenesis of the neuropathy. A sural nerve biopsy from the patient showed a characteristic increase in the width of the intraperiod lines. Deposits of mu-heavy chains and lambda-light chains were found in myelin sheaths of the nerve biopsy. Immunohistochemically, it was demonstrated that mu-heavy chains and lambda-light chains from the patient's serum bound to myelin sheaths of normal peripheral nerves and to a lesser extent to myelin sheaths in the central nervous system (CNS). By immunoblots it was demonstrated that mu-heavy chains and lambda-light chains from the patient's serum bound to myelin associated glycoprotein but to no other antigens from the peripheral and central nervous systems. gamma and alpha heavy chains and chi light chains from the patient's serum were also shown to bind to myelin-associated glycoprotein but not as distinctly as the mu and lambda chains. It is postulated that the monoclonal gammopathy may have arisen on the background of polyclonal autoimmune attack directed against myelin-associated glycoprotein.