Motor neuron disease and plasma cell dyscrasia

Inflammation in ALS/FTD pathogenesis

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that overlap in their clinical presentation, pathology and genetics, and likely represent a spectrum of one underlying disease. In ALS/FTD patients, neuroinflammation characterized by innate immune responses of tissue-resident glial cells is uniformly present on end-stage pathology, and human imaging studies and rodent models support that neuroinflammation begins early in disease pathogenesis. Additionally, changes in circulating immune cell populations and cytokines are found in ALS/FTD patients, and there is evidence for an autoinflammatory state. However, despite the prominent role of neuro- and systemic inflammation in ALS/FTD, and experimental evidence in rodents that altering microglial function can mitigate pathology, therapeutic approaches to decrease inflammation have thus far failed to alter disease course in humans. Here, we review the characteristics of inflammation in ALS/FTD in both the nervous and peripheral immune systems. We further discuss evidence for direct influence on immune cell function by mutations in ALS/FTD genes including C9orf72, TBK1 and OPTN, and how this could lead to the altered innate immune system “tone” observed in these patients.

Autopsy-proven case of paraneoplastic lower motor neuron disease with sensorimotor neuropathy due to Waldenström's macroglobulinemia

We report a case of a male patient with a 19-year history of monoclonal and later polyclonal gammopathy who subsequently developed tetraparesis, bulbar palsy, and respiratory failure. Autopsy findings showed degeneration of the hypoglossal nuclei, prominent neuronal loss and atrophy in the anterior horn of the whole spinal cord despite the presence of mild astrocytosis, degeneration of the gracilis on one side, and infiltration of inflammatory cells, which included B cells and plasma cells in the anterior and posterior roots of the lumbar spinal cord, iliopsoas muscle, and perivascular area of the cervical cord. On immunostaining, cytoplasmic inclusions of phosphorylated transactivation response DNA-binding protein of 43 kDa were observed in the motor neurons and astrocytes of the hypoglossal nuclei and whole spinal cord. The final diagnosis was paraneoplastic lower motor neuron disease with sensorimotor neuropathy due to Waldenström's macroglobulinemia.

Microglia and C9orf72 in neuroinflammation and ALS and frontotemporal dementia

Amyotrophic lateral sclerosis (ALS) is a degenerative disorder that is characterized by loss of motor neurons and shows clinical, pathological, and genetic overlap with frontotemporal dementia (FTD). Activated microglia are a universal feature of ALS/FTD pathology; however, their role in disease pathogenesis remains incompletely understood. The recent discovery that ORF 72 on chromosome 9 (C9orf72), the gene most commonly mutated in ALS/FTD, has an important role in myeloid cells opened the possibility that altered microglial function plays an active role in disease. This Review highlights the contribution of microglia to ALS/FTD pathogenesis, discusses the connection between autoimmunity and ALS/FTD, and explores the possibility that C9orf72 and other ALS/FTD genes may have a "dual effect" on both neuronal and myeloid cell function that could explain a shared propensity for altered systemic immunity and neurodegeneration.

Amyotrophic lateral sclerosis-motor neuron disease, monoclonal gammopathy, hyperparathyroidism, and B12 deficiency: case report and review of the literature

Introduction

Amyotrophic lateral sclerosis (the most common form of motor neuron disease) is a progressive and devastating disease involving both lower and upper motor neurons, typically following a relentless path towards death. Given the gravity of this diagnosis, all efforts must be made by the clinician to exclude alternative and more treatable entities. Frequent serology testing involves searching for treatable disorders, including vitamin B12 deficiency, parathyroid anomalies, and monoclonal gammopathies.

Case presentation

We present the case of a 78-year-old Caucasian man with all three of the aforementioned commonly searched for disorders during an investigation for amyotrophic lateral sclerosis.

Conclusions

The clinical utility of these common tests and what they ultimately mean in patients with amyotrophic lateral sclerosis is discussed, along with a review of the literature.

Motor neuron disease associated with multiple myeloma

The association between Amyotrophic Lateral Sclerosis or other Motor Neuron Diseases (MNDs) with Lymphoproliferative Disorders (LPDs) and plasma cell neoplasias (such as Hodgkin's or non-Hodgkin's lymphoma, Waldenstrom's macroglobulinemia, multiple myeloma, chronic lymphocytic leukemia) has been described. It is not clear whether LPDs play a role in the pathogenesis of MND; however it is possible that patients might have antibodies against motor neurons. An association between motor neuron disease and Multiple myeloma (MM) is rarely reported in the literature. This article reports a case of a 75-year-old male with MM and MND. Interestingly, the patient was in complete remission for MM when he was diagnosed as MND and he died due to progressive MND.

Neurologic Complications of Plasma Cell Disorders

Plasma cell disorders are associated with a wide spectrum of neurologic complications that predominantly involve the peripheral nervous system. Distinct clinical syndromes have been recognized, and antibodies to several glycoproteins of the peripheral nervous system have been identified. The main clinical, laboratory, immunologic, and pathologic features of neurologic complications that occur in patients with monoclonal gammopathies of unknown significance, multiple myeloma, plasmacytoma, plasma cell leukemia, Waldenstrom's macroglobulinemia, and immunoglobulin-related amyloidosis are summarized in this review. Knowledge of the pathogenesis in this group of disorders has increased in recent years, allowing better diagnosis and treatment.

Les neuropathies périphériques paranéoplasiques

Paraneoplastic peripheral neuropathies constitute a heterogeneous group of conditions. A link between the tumor and the neuropathy has been demonstrated in a subgroup only. Definite paraneoplastic neuropathies correspond to neuropathies associated with antibodies reacting with antigens common to the peripheral nervous system and the cancer. Neuropathies associated with anti-Hu antibodies are the most frequent and consist mainly in subacute sensory neuronopathy. Sensory or sensory-motor neuropathies with anti-CV2 antibodies are less frequent. The link between the cancer and the neuropathy is less clear in the other forms. The frequency of cancer in this group varies from 1 to 18 p.cent.These neuropathies include inflammatory demyelinating neuropathies, neuropathy and vasculitis, lower motor neurone diseases, and autonomic neuropathies. Occasionally, the neuropathy improves with treatment of the tumor. Recent data suggest that gangliosides may be the target of the immune process in neuropathies associated with melanoma.

Sporadic lower motor neuron disease with adult onset: classification of subtypes

The discovery of the genetic basis of hereditary lower motor neuron disease (LMND) and the recognition of multifocal motor neuropathy as a distinct clinical entity necessitate a new classification of LMND. To this end, we studied the clinical and electrophysiological features of 49 patients with sporadic adult-onset LMND in a cross-sectional study. Disease duration was more than 4 years to exclude the majority of patients with amyotrophic lateral sclerosis. Based on the pattern of weakness, we identified three groups: 13 patients with generalized weakness (group 1); eight patients with symmetrical, distal muscle weakness (group 2); and 28 patients with non-generalized asymmetrical weakness of the arms in most patients (group 3). Group 3 could be subdivided into patients with weakness in predominantly the distal (group 3a) or the proximal (group 3b) muscle groups, both with disease progression to adjacent spinal cord segments. Distinctive features of group 1 were an older age at onset, more severe weakness and muscle atrophy, lower reflexes, greater functional impairment, more widespread abnormalities on concentric needle EMG, respiratory insufficiency and serum M-protein. In groups 2 and 3, concentric needle EMG findings also suggested a more widespread disease process. Retrospectively, the prognosis of sporadic adult-onset LMND appears to be favourable, because clinical abnormalities were still confined to one limb in most patients after a median disease duration of 12 years. We propose to classify the patients in the different subgroups as slowly progressive spinal muscular atrophy (group 1), distal spinal muscular atrophy (group 2), segmental distal spinal muscular atrophy (group 3a) and segmental proximal spinal muscular atrophy (group 3b). The described clinical phenotypes may help to distinguish between different LMND forms.

Retrospective cohort study of 148 patients with polyclonal gammopathy

OBJECTIVE

To quantify clinical conditions and laboratory values associated with moderate to marked polyclonal gammopathy.

PATIENTS AND METHODS

Patient characteristics, laboratory correlates, evolving disease states, and survival of all patients seen at the Mayo Clinic, Rochester, Minn, during 1991 with a polyclonal gamma globulin level of 3.0 g/dL or higher were reviewed in this retrospective cohort study.

RESULTS

One hundred forty-eight patients were identified (median age, 58 years; 59% female). In 130 patients (88%), only 1 diagnosis was identified. Liver disease was the most common single disease association in 79 (61%) of 130 patients, followed by connective tissue diseases in 28 (22%), chronic infections in 8 (6%), hematologic disorders in 6 (5%), and nonhematologic malignancies in 4 (3%). No difference in gamma globulin levels existed between groups. With a median follow-up of 67 months, 90 (63%) of 143 patients for whom follow-up was available were alive. By multivariate analysis, age, albumin concentration, disease group, and platelet count were predictive of survival. No patient developed myeloma or a clonal plasmaproliferative disorder.

CONCLUSION

Moderate to marked polyclonal gammopathy may reflect an underlying condition: liver disease, connective tissue disease, hematologic disorder, infection, or malignancy.

Serum autoantibodies to neurofilament proteins in sporadic amyotrophic lateral sclerosis

Anti-neurofilament (NF) autoantibodies were searched for by enzyme-linked immunosorbent assays (ELISA) in the serum from 85 sporadic amyotrophic lateral sclerosis (ALS) patients, 98 healthy controls and 79 patients with unrelated immunological diseases (Guillain-Barré syndrome, myasthenia gravis and multiple sclerosis). ELISA cutoff value was determined as mean control levels +2 SD and it corresponded to a specificity of 94%. Such high level antibodies were detected in 24.7% of ALS patients contrasting with 12.6% of neurological controls (P<0.05) and only 6.1% of healthy subjects (P<5.10[-4]). In ALS, anti-NF antibodies were significantly associated with a slow evolution, as measured by the mean time spent in the initial functional states. They did not relate with age, sex and clinical form. The predominant isotype of the anti-NF antibodies was IgM lambda by ELISA. In contrast to negative sera, indirect immunohistochemical studies demonstrated that most sera positive for anti-NF antibodies reacted with axons with predominant isotypes restricted to IgM lambda. By using Western blotting, small amounts of serum monoclonal IgM were found with a high frequency in anti-NF antibody-positive patients. These results suggest the possible involvement of anti-NF antibodies in an autoimmune process in a subgroup of ALS patients.

A novel monoclonal antibody which reacts with a high molecular weight neuronal cytoplasmic protein and myelin basic protein (MBP) in a patient with macroglobulinemia

We report on the case of a 70-year-old man with primary macroglobulinemia who showed cranial polyneuropathy and extensive radiculoneuropathy. His serum contained an IgM lambda monoclonal antibody which reacted with both a high molecular weight protein in grey matter and purified myelin basic protein (MBP) on immunoblotting. In an immunohistochemical study, strong immunoreactivity was detected only in the cytoplasm of neurons and weak immunoreactivity was detected in myelin. These findings suggest that this antibody may be related to the pathogenesis of neuronal damage in patients with macroglobulinemia.

Uptake of immunoglobulin G from amyotrophic lateral sclerosis patients by motor nerve terminals in mice

Clinical and experimental evidence support an autoimmune etiopathogenesis for amyotrophic lateral sclerosis (ALS). We have shown that local application of ALS-IgG onto nerve terminals induces dysfunction in transmission at the neuromuscular junction. It has been established that IgG and other circulating serum proteins can be taken up by motor nerve terminals, being immunolocalized in the soma where they accumulate following retrograde axonal transport. In the present study, we investigated the presence of human ALS and control IgG in the soma of mouse motoneurons. IgG was applied onto motor nerve terminals of mice by subcutaneous injections on the left levator auris longus muscle which is innervated by a branch of the facial nerve. After several injections, sections of the brainstem containing the facial nuclei were immunoprocessed to detect human IgG. For all IgG tested, motoneuron labeling was significantly more intense in the facial nucleus ipsilateral to the site of injection. In ALS-IgG-treated animals, ipsilateral labeling was significantly stronger than that found on the ipsilateral side of control IgG-treated animals. Our results are compatible with the concept that motoneurons preferentially take up, transport and/or accumulate ALS-IgG. Uptake of pathogenic antibodies by motoneuron terminals may play a role in the pathogenesis of motoneuron disease.

Association of polyclonal anti-GM1 IgM and anti-neurofilament antibodies with CSF oligoclonal bands in a young with amyotrophic lateral sclerosis

INTRODUCTION

The significance of the association of motor neuron syndromes with anti-GM1 antibodies remains unclear. We report the immunological study of a juvenile case of amyotrophic lateral sclerosis (ALS).

MATERIALS AND METHODS

Serum anti-Gm1 and anti-neurofilament antibodies were assayed by ELISA and western blotting and cerebrospinal fluid (CSF) isoelectrofocusing was performed. Immunocytochemical studies were carried out with the patient's serum and CSF on human brain and spinal cord sections.

RESULTS

Serum polyclonal IgM anti-GM1, anti-neurofilament antibodies and CSF oligoclonal bands were detected. Furthermore, an in vitro production of anti-GM1 IgM was demonstrated. Immunocytochemical studies showed cytoplasm motor neuron immunostaining, due to both IgG and IgM, that substantially decreased after immunoabsorption of the serum with bovine neurofilament proteins but not with GM1-containing liposomes. No immunostaining was obtained with CSF. Immunosuppressive treatment with cyclophosphamide and two cycles of plasma exchanges lowered anti-GM1 antibody levels, but did not determine any clinical improvement.

CONCLUSION

To our knowledge, this is the first report of ALS, associated with circulating levels and in vitro production of polyclonal IgM anti-GM1, anti-neurofilament antibodies and CSF oligoclonal bands. These findings suggest the occurrence in our patients of an autoimmune process that could be involved in the pathogenesis of ALS.

Molecular approaches to amyotrophic lateral sclerosis

New discoveries are expanding our knowledge of mechanisms involved in amyotrophic lateral sclerosis (ALS) pathogenesis. Some recent advances in our understanding of motoneuron death in familial ALS (fALS) and sporadic ALS (sALS) are reviewed, with emphasis on molecular similarities that may further unite these phenotypically linked diseases.

Amyotrophic lateral sclerosis immunoglobulins increase Ca2+ currents in a motoneuron cell line

The sporadic form of amyotrophic lateral sclerosis (ALS) is an idiopathic and eventually lethal disorder causing progressive degeneration of cortical and spinal motoneurons. Recent studies have shown that the majority of patients with sporadic ALS have serum antibodies that bind to purified L-type voltage-gated calcium channels and that antibody titer correlates with the rate of disease progression. Furthermore, antibodies purified from ALS patient sera have been found to alter the physiologic function of voltage-gated calcium channels in nonmotoneuron cell types. Using whole-cell patch-clamp techniques, immunoglobulins purified from sera of 5 of 6 patients with sporadic ALS are now shown to increase calcium currents in a hybrid motoneuron cell line, VSC4.1. These calcium currents are blocked by the polyamine funnel-web spider toxin FTX, which has previously been shown to block Ca2+ currents and evoked transmitter release at mammalian motoneuron terminals. These data provide additional evidence linking ALS to an autoimmune process and suggest that antibody-induced increases in calcium entry through voltage-gated calcium channels may occur in motoneurons in this disease, with possible deleterious effects in susceptible neurons.

GM1, a ganglioside that specifically enhances immunoglobulin production and proliferation in human plasma cells

The effects of gangliosides on human plasma cell responses were studied. Among the various gangliosides tested, only GM1 enhanced immunoglobulin (Ig) production and proliferation in the human plasma cell lines, IM-9 and AF-10, while other gangliosides (GM2, GM3, GD1a, GD1b, GD3, GT1b, and GQ1b) had no effect. Among the various cytokines tested, including interleukin (IL)-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12, IL-13, interferon (IFN)-alpha and IFN-gamma, only IL-6 enhanced Ig production and proliferation in IM-9 and AF-10 cells. However, the enhancement of plasma cell responses by GM1 was specific and was not mediated by IL-6, since GM1 activity was blocked by anti-GM1 monoclonal antibody (mAb), but not by control IgM, anti-IL-6 Ab or the anti-IL-6 receptor mAb, PM1. Conversely, the enhancement by IL-6 was blocked by anti-IL-6 Ab and PM1, but not by anti-GM1 mAb. GM1, but not other gangliosides, also enhanced Ig production and proliferation in freshly separated plasma cells from patients with plasma cell leukemia and in plasma cells generated in vitro. These actions of GM1 were specifically blocked by anti-GM1 mAb, but not by anti-IL-6 Ab or PM1. These results indicate that GM1 may be an important regulator of plasma cell responses.

Evidence for autoimmunity in amyotrophic lateral sclerosis

Although the etiology and pathogenesis of ALS is unknown, increasing evidence supports a role for autoimmune mechanisms in motoneuron degeneration and death. An animal model, experimental autoimmune gray matter disease, can be induced by the inoculation of spinal cord gray matter. The experimental disease is characterized by weakness secondary to the loss of upper and lower motoneurons, accompanied by inflammatory foci within the spinal cord, and IgG at the neuromuscular junction and within UMN and LMN. In human ALS, IgG is present within the UMN and LMN, and T-lymphocytes and activated microglia have been identified within spinal cord gray matter and motor cortex. ALS IgG can passively transfer physiological changes of the neuromuscular junction to mice resulting in enhanced release of acetylcholine. The ALS IgG selectively interact with calcium channels and alter channel function. These data suggest a potential role for autoimmune mechanisms in the destruction and loss of motoneurons in ALS.

Treatment of ALS with high dose pulse cyclophosphamide

Autoimmune abnormalities have been described in sporadically acquired amyotrophic lateral sclerosis (ALS), but ALS patients do not benefit from conventional immunosuppressive therapy. Because Multifocal Motor Neuropathy causes a syndrome mimicking the lower motor neuron involvement in ALS and responds to high dose cyclophosphamide, we tested whether ALS patients would respond to the same treatment. Eighteen patients with classical ALS initially received a high loading dose of intravenous cyclophosphamide (3 g/m2) followed by 6-monthly injections of 750-1000 mg/m2. We monitored isometric strength, fine motor coordination and pulmonary function monthly for 3 months prior to the study, during the treatment phase, and for 6 months after treatment. Treatment subjects were matched to control subjects from the WALS natural history data base and compared on the basis of decline rate (megaslopes). Treatment did not alter the course of ALS.

Immunofixation superior to plasma agarose electrophoresis in detecting small M-components in patients with polyneuropathy

Monoclonal immunoglobulins (M-components) in blood are found in some patients with polyneuropathy and are thought to be of pathogenetic importance, especially if the M-component is of IgM isotype. As the finding of an M-component may indicate a treatable polyneuropathy, the potential of the method to uncover an M-component is of importance. Cellulose acetate or agarose electrophoresis used in routine practice may miss small M-components covered by other proteins. We therefore applied the uncovering and specific method of immunofixation in comparison with agarose electrophoresis on patients investigated for polyneuropathy. Of 83 consecutive patients, 5 had M-components. Two of these 5 patients, one with an axonal polyneuropathy and the other with a lower motor neuron syndrome, had extra bands on agarose electrophoresis, verified as IgG M-components by immunofixation. In the 3 additional patients an M-component was uncovered only by immunofixation, not seen in the agarose electrophoresis of plasma; 2 of them were of IgM isotype and one was of IgG isotype. These 3 patients were diagnosed as having a demyelinating (i.e., possibly immune-mediated) polyneuropathy by means of neurophysiology and in one by means of nerve biopsy. A 6th patient had 2 small bands in the gamma region on the agarose electrophoresis, verified as oligoclonal bands of IgG isotype by immunofixation but was not judged as an M-component. Three out of the 83 patients, were judged as having motor neuron diseases. All remaining 80 were found to have polyneuropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for autoimmunity in amyotrophic lateral sclerosis

Although the etiology and pathogenesis of ALS is unknown, increasing evidence supports a role for autoimmune mechanisms in motoneuron degeneration and death. An animal model, experimental autoimmune gray matter disease, can be induced by the inoculation of spinal cord gray matter. The experimental disease is characterized by weakness secondary to the loss of upper and lower motoneurons, accompanied by inflammatory foci within the spinal cord, and IgG at the neuromuscular junction and within UMN and LMN. In human ALS, IgG is present within the UMN and LMN, and T-lymphocytes and activated microglia have been identified within spinal cord gray matter and motor cortex. ALS IgG can passively transfer physiological changes of the neuromuscular junction to mice resulting in enhanced release of acetylcholine. The ALS IgG selectively interact with calcium channels and alter channel function. These data suggest a potential role for autoimmune mechanisms in the destruction and loss of motoneurons in ALS.

A characteristic ganglioside antibody pattern in the CSF of patients with amyotrophic lateral sclerosis

Paired cerebrospinal fluid and serum samples of patients with amyotrophic lateral sclerosis (n = 35) revealed no consistent abnormalities of CSF cell count, CSF albumin, CSF IgG, CSF IgM, IgG or IgM index, or oligoclonal immunoglobulin band formation in the CSF. Determination of IgG and IgM CSF and serum antibodies to gangliosides GM1, GM2, GM3, AGM1, GD1a, GD1b, and GT1b showed a characteristic pattern which allowed the differentiation of amyotrophic lateral sclerosis from controls and from patients with other neurological disorders including multiple sclerosis. Specifically, patients with the disease had elevated CSF IgM antibodies to all gangliosides except AGM1. The lack of correlation between the CSF findings and corresponding serum antibodies suggests a chronic, compartmental, intrathecal immune response of low activity in amyotrophic lateral sclerosis. Whether this immune response is primary and of pathogenetic significance, or an epiphenomenon of neuronal degeneration, remains to be investigated.

Antiglycolipid antibodies, immunoglobulins and paraproteins in motor neuron disease: a population based case-control study

The role of humoral autoimmune factors in the pathogenesis of motor neuron disease (MND) is currently under considerable scrutiny. In particular, there have been many reports of abnormal serum immunoglobulin patterns and elevated titres of anti-ganglioside antibodies in patients with MND. However, many of these studies may be biased by the selection criteria for patients and controls. In order to carefully address this issue we obtained 82 blood samples from consecutive MND patients identified through a national MND register in combination with 82 community controls matched for age, sex and geographical area. We used these samples to determine the frequency of monoclonal immunoglobulins (mIgs) and measure the levels of serum immunoglobulins and anti-GM1 ganglioside antibodies in sporadic cases of MND in comparison with normal controls. Serum mIgs detected using high resolution and immunofixation agarose electrophoresis were present in 1.2% of MND patients and 2.4% of controls. Using a highly sensitive isoelectric focusing and immunoblotting method, monoclonal or oligoclonal immunoglobulins were found in 28% of MND patients and 27% of controls. Anti-GM1 antibodies were present in 26% of MND patients and 18% of controls (odds ratio = 1.5, 95%, CI 0.7-3.6) with no significant differences in titres between the 2 groups. Mean immunoglobulin G, A and M levels were equal in 2 groups. Thus, although alterations in these parameters were identified, we were unable to demonstrate any significant difference between MND patients and controls. We conclude that the majority of sporadic cases of MND are unlikely to have an autoimmune basis as judged by the lack of abnormalities in these parameters.

Clinical, neurophysiological and immunological evidence of polyneuropathy in patients with monoclonal gammopathies

In this study we estimated the prevalence of polyneuropathy (PN) in patients with monoclonal gammopathies. 31 patients with monoclonal gammopathies (19 with monoclonal gammopathy of uncertain significance (MGUS), 10 with multiple myeloma (MM), and 2 with Waldenström's macroglobulinemia), were studied by clinical and neurophysiological examination, blood tests to exclude other causes of PN, ELISA assays to detect antibodies to peripheral nerve myelin (PNM), and antibodies to myelin associated glycoprotein (MAG). 11 of 31 patients (36%) had a clinical PN, 3 (10%) had a probable PN (signs but no symptoms), and 4 (13%) had a subclinical PN (only neurophysiological signs of PN). Thus, in total 18 patients (58%) had some form of PN, in contrast to an age-matched control group (n = 33) where only 2 persons (6%) had some form of PN; 1 had a probable PN and 1 had a subclinical PN. 3 patients had anti-PNM and anti-MAG antibodies of IgM isotype, all 3 patients showing a demyelinating PN. The remaining patients with PN had a mild or moderate distal PN. One patient had a myelopathy and 1 had amyotrophic lateral sclerosis (ALS). IgM isotype of the M-protein was associated with a high risk of clinical PN (5 out of 6 (83%)), in contrast to IgG (5 out of 18 (28%)) and IgA (1 out of 6 (17%)). We conclude that PN is a common finding in patients with monoclonal gammopathies, but only some of them are of the demyelinating type and associated with antibodies to PNM or MAG.

Experimental immune-mediated motor neuron diseases: models for human ALS

Amyotrophic lateral sclerosis is an idiopathic, ultimately fatal disease, clinically manifest as progressive weakness and spasticity, associated with the loss of motoneurons. Circumstantial evidence supports a role for autoimmune processes in the progression of this human disorder. Two immune-mediated animal models have been developed in our laboratory for motor neuron loss. Experimental autoimmune motor neuron disease is a lower motor syndrome induced in guinea pigs by the repeated injection of a purified bovine spinal motor neuron antigen. Affected animals demonstrate extremity weakness, associated with electromyographic and morphologic evidence of denervation, a loss of spinal cord motor neurons, high antibody titers against motor neurons, and localization of IgG immunoreactivity to the neuromuscular junction and motor neuron cytoplasm. Experimental autoimmune grey matter disease is a more acute and severe disorder involving both upper and lower motor neurons, induced in guinea pigs by inoculation of a bovine ventral spinal cord homogenate, in which scattered foci of denervation are observed in the motor cortex and ventral spinal cord. Similarities between these diseases and human ALS are reviewed.

What do we really know about amyotrophic lateral sclerosis?

The cause of amyotrophic lateral sclerosis is unknown. In this review clinical and scientific data that are pertinent to understanding this disease are reviewed. There are currently several major controversies concerning the possible role of immunological factors, genetic factors, environmental toxins, and viral infection in pathogenesis. These concepts must be considered in relation to what is known about the disease in all its aspects, including epidemiological data, information on the classical and molecular pathology of the disease, and on associated involvement of other systems, e.g., the spinocerebellar pathways and frontal dementia. Only when all this information is assimilated can full understanding of the disease and, hopefully, a logical approach to treatment and prevention, be achieved.

Sensorimotor polyneuropathy and monoclonal IgM: a review of clinical and immunological features

Main clinical and biological features of peripheral neuropathies associated with monoclonal IgM are reviewed. Special emphasis is given to the structure of these monoclonal auto-antibodies which points to an antigen (or some other kind of selective pressure) driven process.

Frontal lobe function in amyotrophic lateral sclerosis: a neuropsychologic and positron emission tomography study

In this study the regional cerebral glucose utilization and the neuropsychological performance of patients with amyotrophic lateral sclerosis (ALS) was investigated. Special attention was given to neuropsychological tests thought to mirror frontal lobe dysfunction. The regional cerebral glucose utilization was studied in 18 patients using high-resolution positron emission tomography. Clinically all patients displayed upper and lower motor neurone signs. In ALS patients glucose metabolism was significantly reduced in the frontal and in the entire cortex compared with controls; no changes were seen in the cerebellum. Comprehensive neuropsychological assessment of ALS patients compared to a pair matched control group revealed mild frontal dysfunction which in part significantly correlated with reduced glucose metabolism in the cortex and subcortical structures. We conclude that in patients with ALS, glucose consumption is decreased in parts of the brain other than the motor cortex accompanied by mild neuropsychological deficits based on the tests employed in this study.

Peripheral neuropathy and multiple myeloma in aging: a case report

A 67-year-old man affected by moderate weight loss, acral paresthesia and plantar burning sensation was admitted to our department. Electromyographic (EMG) and electroneurographic (ENG) studies confirmed a peripheral, asymmetrical, motor-sensorial polyneuropathy (PPN). Hematological data and bone marrow biopsy discovered a non-secerning multiple myeloma (MM). All other probable causes of peripheral neuropathy could be excluded, and the possible relationship between nerve damage and neoplasia was confirmed. Furthermore, all possibilities of association of MM with PPn, namely the osteosclerotic variant, the Crow-Fukase syndrome, and the amyloid one have been evaluated. The only finding of osteolytic bone areas by radiology, the absence of organomegaly, diabetes mellitus, skin alterations, and of amyloid deposition in muscles and nerves, exclude the possible connection of the case to any of the listed possibilities. On the other hand, some clinical aspects differ, in part, to others described in the literature. In conclusion, the association between PPN and MM as the result of multiform clinical variants could be considered.

Detection of nephrotoxicity in cyclosporine-A amyotrophic lateral sclerosis patients by means of urinary cytology

Exfoliative urinary cytology was used for two amyotrophic lateral sclerosis patients treated with 3 mg/kg/day cyclosporine (CsA) therapy in order to detect the onset of the nephrotoxic side-effects of the drug before the apparent deterioration of the patients' clinical condition. Of the two patients, only one showed clear morphological features of drug-related damage in a one year course of cyclosporine therapy, but these followed the increase in the serum kidney and liver laboratory parameters and did not prove useful for the early detection of nephrotoxicity. However, in this patient the renal damage was hallmarked by an increasing number of tubular cells or clusters of ill-defined renal cells in the urinary specimen, suggesting an ongoing tubular injury. The slight cytological alterations may possibly be due to the low CsA dosage used for these patients. The significance of these observations is tempered by the limited number of patients and specimens studied to date and further studies in nontransplanted patients are therefore advocated, particularly when higher CsA doses are employed.

Immunosuppressive treatment in multifocal motor neuropathy

We report the results of immunosuppressive treatments of 13 patients with multifocal motor neuropathy and elevated titers of serum antibodies to the GM1 ganglioside. All patients failed to respond to oral prednisone. There was no clinical response in 4 patients treated with plasma exchange. Nine patients received cyclophosphamide, with clinical improvement and fall in antibody titers in 8. In 3 patients, cyclophosphamide was discontinued with ensuing clinical relapse and rise in the titers of serum anti-GM1 antibodies. These patients provide further evidence for the efficacy of cyclophosphamide therapy in patients with multifocal motor neuropathy.

Penetration and internalization of plasma proteins in the human spinal cord

In animal studies, motoneurons take up plasma proteins including immunoglobulins at their terminals. These proteins are then transported back to cell bodies in the spinal cord. To determine if these processes also occur in humans, we localized several different plasma proteins in autopsied spinal cords from 13 patients without neurological disease. As in animals, plasma proteins are associated with vascular and pial structures. Motoneurons, particularly large cervical and lumbar motoneurons, frequently showed immunoreactivity within their cytoplasm to several plasma proteins. Motoneuron labeling was more consistent with antisera against plasma proteins of lower molecular weights such as IgG, IgA and transferrin, than with antisera against higher molecular weight proteins such as IgM and alpha-2-macroglobulin. Other large neurons without connections outside the blood-brain barrier such as those of Clarke's column also occasionally labeled with antisera against all plasma proteins tested. Our results are compatible with the concept that motoneurons take up and transport plasma proteins. These neurons can be distinguished from cells which internalized extravasated serum proteins before and after death. Uptake of pathogenic antibodies by motoneuron terminals may play a role in the pathogenesis of motoneuron disease.

Quantitative analysis of monoclonal immunoglobulins in serum of patients with amyotrophic lateral sclerosis

In a prospective study, we analysed the presence of monoclonal immunoglobulin (moIg) in the serum from 30 patients with amyotrophic lateral sclerosis (ALS) and 30 matched controls using a sensitive Western blot technique. The incidence of serum moIg was 60% in the ALS group and 13.3% in the control group. Most ALS sera contained 2 or 3 monoclonal components. They were IgG (72.7%) and IgM (27.3%). These results corroborate the concept of a probable association between ALS and serum moIg.

Lymphoma, motor neuron diseases, and amyotrophic lateral sclerosis

We studied 9 patients with motor neuron disease and lymphoma. The following several observations have not been recognized in the past: (1) Motor neuron syndromes are associated with either Hodgkin's disease or non-Hodgkin's lymphoma. (2) The syndromes are not restricted to lower motor neuron disorders; 8 of 9 patients had definite or probable upper motor neuron signs as well, qualifying for the diagnosis of amyotrophic lateral sclerosis. Corticospinal tracts were affected in both postmortem examinations. (3) The combination of motor neuron disease and lymphoma is often accompanied by paraproteinemia (3 of 7 patients studied), increased cerebrospinal fluid protein content (6 of 9 patients), and cerebrospinal fluid oligoclonal bands (3 of 9 patients). (4) In 2 patients, asymptomatic non-Hodgkin's lymphoma was found only because the discovery of paraproteinemia gave impetus to examine the bone marrow. (5) Patients with both upper and lower motor neuron signs (amyotrophic lateral sclerosis) may show physiological evidence of conduction block in peripheral nerves or autopsy abnormalities in peripheral nerves. The cause of this syndrome is not known. Both lymphoma and motor neuron disease could have a common cause, possibly a retroviral infection. The frequency of paraproteinemia suggests that an immunological disorder may play a role in the pathogenesis of the neurological disorder.

Motor neuron disease (amyotrophic lateral sclerosis)

Amyotrophic lateral sclerosis is an insidiously developing, adult-onset, progressive anterior horn cell degeneration with associated degeneration of descending motor pathways. It has been recognized as an important clinical syndrome since the middle of the 19th century. Despite increasing clinical and research interest in this condition, its cause remains obscure, even in the broadest terms. Epidemiologic characteristics of the disease have been interpreted as evidence of both genetic and environmental causes. A major change in the view of this disease is the widely developing perception that it is a disease of elderly persons more than of middle-aged adults as was previously taught. Etiologic hypotheses encompass a broad range of postulated pathophysiologic mechanisms, and we review these in detail. The clinical limits of the disease can now be better defined by using modern diagnostic techniques. Although interest in supportive symptomatic therapy is growing, no intervention has yet been shown to modify the biologically determined motor system degeneration.

Major histocompatibility complex antigen expression in the affected tissues in amyotrophic lateral sclerosis

Monoclonal antibody immunocytochemistry was used to examine spinal cord and muscle in amyotrophic lateral sclerosis for changes that would indicate ongoing or potential immune activity. Increased expression of class I and II major histocompatibility complex (MHC) antigens was seen in the affected areas of spinal cord. New MHC expression was concentrated in phagocytes, particularly in degenerating white matter in which they were dispersed in the tissue and also packed around blood vessels. MHC antigen was not revealed in motor neurons or skeletal muscle fibers. An anti-pan-T-cell monoclonal revealed small numbers of T cells in degenerating white matter. Similar changes have been seen in other neurodegenerative disorders. They suggest a potential for (secondary) cell-mediated activity in the affected areas rather than an ongoing MHC-restricted T-cell response. Vessel-associated phagocytes may be a source of antigen to peripheral lymphoid tissue, stimulating production of the autoantibodies that have been described.

Experimental autoimmune motoneuron disease

An animal model of disease of the lower motoneurons has been developed by inoculating guinea pigs with bovine motoneurons. Four of 9 immunized female animals and 4 of 5 immunized male animals developed symptoms of neuromuscular degeneration marked by weakness, evidence of denervation by electromyographic and morphological criteria, and a loss of motoneurons within the spinal cord. No inflammatory foci were noted within parenchyma or meninges of the central nervous system. The immunized guinea pigs developed high serum titers of IgG class antibodies to motoneurons. Immunohistochemical studies demonstrated the presence of IgG within spinal cord motoneurons and at the end-plates of immunized animals. This experimental autoimmune motoneuron disease may provide important insights into the cause and pathogenesis of amyotrophic lateral sclerosis, a human motoneuron disease.

Amyotrophic lateral sclerosis: an unconventional autoimmune disease?

The possibility of an autoimmune mechanism of pathogenesis in amyotrophic lateral sclerosis has long been considered, but the evidence to support a conventional autoimmune process, reviewed here, is inconclusive. However, antibodies that react in vitro with gangliosides have recently been found in sera of a large majority of patients with classical amyotrophic lateral sclerosis and other motor neuron syndromes. A working hypothesis is proposed, suggesting how antibodies might be related to the disease process. The hypothesis attempts to account for (1) a pathogenic role of antibodies directed against the carbohydrate components of glycolipids, (2) the selectivity of the process for motor neurons, (3) an antibody-mediated mechanism that could result in apparently degenerative neuropathological changes without signs of inflammation, and (4) a type of autoimmune response that is extremely difficult to suppress by conventional means. Although the evidence for this hypothesis is by no means complete, its critical features are all testable.