Myeloma neuropathy: passive transfer from man to mouse

Contribution of electron microscopy to the study of neuropathies associated with an IgG monoclonal paraproteinemia

A typical monoclonal IgG dysglobulinemia whether benign (monoclonal gammopathy of undetermined significance, MGUS) or malignant can give rise to peripheral neuropathy by damaging nerves. At first, neurotoxicity of the chemotherapy if the patient is treated must be ruled out in such cases. Indeed, a variety of other mechanisms have been described: endoneurial deposits of immunoglobulin, infiltration of the immunoglobulin within myelin sheaths, POEMS syndrome, deposits of amyloid, chronic inflammatory demyelinating polyradiculoneuropathy and infiltration of malignant cells. Ultrastructural examination of a nerve biopsy can be decisive in combination with routine histological and immunopathological examinations. Characterization of the mechanism of the neuropathy in a dysglobulinemic context is important as it governs therapeutic options, which in certain cases are particularly beneficial.

Paraproteinemic neuropathy

Paraproteinemia frequently is associated with peripheral neuropathy. The clinical manifestations can be protean owing to the potential for multiple organ involvement. A methodical diagnostic approach to patients who have a plasma cell dyscrasia and neuropathy is necessary to ensure the appropriate detection of more widespread systemic involvement.

POEMS in childhood

A 17-year-old boy had a 3-year history of diabetes mellitus, malabsorption syndrome, and skin changes consisting of induration, hyperpigmentation, and hypertrichosis on the anterior aspect of both thighs, lower abdomen, and scrotum. Physical examination found hypogonadism, hepatomegaly, gynecomastia, growth retardation, and ankle edema. There was no neuropathy or plasma cell dyscrasia. However, the characteristic skin changes and the combination of symptoms suggest polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes syndrome. This is a rare multisystemic disorder of obscure pathogenesis and no conspicuous heredity. Overproduction of vascular endothelial growth factor is thought to cause microangiopathy, neovascularization, and accelerated vasopermeability causing the multiorgan deterioration. Cyclophosphamid cytostatic therapy seems beneficial.

A complement-dependent model of thrombotic thrombocytopenic purpura induced by antibodies reactive with endothelial cells

Thrombotic thrombocytopenic purpura (TTP) is an immunologically mediated disease characterized by thrombocytopenia, hemolytic anemia, and pathologic changes in various organs, including the kidney, which are secondary to widespread thromboses. Central to TTP is platelet activation, which may occur from a variety of mechanisms, including endothelial cell activation or injury. In this study, injection of K6/1, a monoclonal antibody with widespread reactivity toward endothelia, led to dose-dependent thrombocytopenia in rats. This was magnified if animals were preimmunized with mouse IgG, thereby resulting in an accelerated autologous phase of injury. In this setting, significant anemia also resulted. Rats injected with K6/1 developed renal injury, consisting of tubular damage and glomerular thrombi. Thrombocytopenia and renal morphological abnormalities were eliminated if animals were complement depleted with cobra venom factor prior to K6/1 injection and worsened when the activity of the ubiquitous complement regulator Crry was inhibited with function-neutralizing antibodies. Therefore, we have developed a complement-dependent model of TTP in rats by injecting monoclonal antibodies reactive with endothelial cells. Antibody-directed complement activation leads to stimulation of platelets, through direct interactions with complement fragments and/or indirectly through endothelial cell activation or injury, with the subsequent development of TTP.

Overproduction of vascular endothelial growth factor/vascular permeability factor is causative in Crow-Fukase (POEMS) syndrome

Crow-Fukase or POEMS syndrome of polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes is a rare multisystem disorder of obscure pathogenesis that is associated with microangiopathy, neovascularization, and accelerated vasopermeability. We examined the levels of the vascular endothelial growth factor/vascular permeability factor (VEGF) in the serum and cerebrospinal fluid (CSF) from 10 patients with this syndrome. Serum VEGF levels were about 15-30 times those in control subjects or patients with Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and other neurological disorders. The CSF VEGF levels, however, were similar to those found in GBS and CIDP. Elevated VEGF levels in the serum decreased in 7 patients with Crow-Fukase syndrome after conventional therapy. The principal isoform of VEGF in Crow-Fukase syndrome was VEGF165. Elevated VEGF was independent of M-protein. Our results suggest that the overproduction of VEGF is important in the pathogenesis of this disorder.

[Therapeutic plasma exchange 1996]

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique to remove large molecular weight substances. Since the late seventies TPE was used in a variety of diseases in which humoral factors may play a part in the pathogenesis. Today, accepted indications only exist for a few entities in defined situations: Anti-glomerular basement membrane antibody mediated disease, TTP/HUS, Guillain-Barré-syndrome, hyperviscosity syndrome, chronic polyneuropathy associated with IgG and IgA gammopathy, chronic inflammatory demyelinating polyneuropathy and myasthenia gravis.

[POEMS syndrome]

POEMS syndrome is an acronym defined by Bardwick (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal component and Skin changes). Other various clinical and biological features are reported: edema, cachexia, microangiopathic glomerulopathy, most rarely pulmonary hypertension, cutaneous necrosis. Thrombocytosis or polycythemia may be a prominent feature. POEMS syndrome is sometimes associated with lymphoproliferative disorder. Castelman-like disease is frequently observed as pathologic findings on lymph nodes. Distinction between POEMS syndrome and osteosclerotic myeloma is delicate. The rate of the monoclonal protein is modest-always less than 30 g/L-and is almost of the lambda light chain class. In contrast to multiple myeloma this syndrome is rarely associated with hypercalcemia, skeletal fracture, renal involvement and increasing of M component during evolution. Bone marrow plasmocytosis is usually less than 15% and the kinetic phenotype and genetic characteristics of the plasma cell remain those found in monoclonal gammopathy of undetermined significance. The pathophysiology of this syndrome remains largely unknown but overproduction of pro-inflammatory cytokines are reported, especially TNF alpha, IL-6 and IL-1 beta. Some clinical manifestations seem to be cytokine related. Polyneuropathy and cachexia are the main cause of death. A part corticosteroid and cure of solitary bone lesion, treatment is disappointing and survival is 60% at five years.

Multifocal motor neuropathy human sera block distal motor nerve conduction in mice

Multifocal motor neuropathy (MMN) is associated with serum autoantibodies to gangliosides, but their pathogenic role is uncertain. We have used a novel approach to study the effects of serum and plasma from 8 patients with this syndrome, 6 of whom were anti-GM1 positive. The nerve stimulus required to evoke muscle contraction and endplate potentials (EPPs) was measured in the mouse phrenic nerve-diaphragm preparation during 4 to 6 hours of direct application (plasma at 1:1 or serum 1:2 dilution) and following intraperitoneal injection of plasma (1 ml/day) for 1 to 5 days ("passive transfer"). Direct application of MMN serum or plasma produced a progressive increase in stimulus threshold, followed by complete block of nerve-evoked muscle contraction in 3 cases, and an associated decline to about 50% of the EPP amplitude followed by sudden loss of EPPs. These effects were complement independent. Even with complete block of nerve-evoked EPPs, miniature EPP (MEPP) frequency could be increased by raising external K+ to depolarize the nerve terminal directly. Passive transfer of 1 ml of MMN plasma (n = 5) for 3 days caused similar but less marked changes. These results demonstrate that serum factors in MMN can block nerve conduction at distal motor nerves.

Pathogenesis and therapy of neuropathies associated with monoclonal gammopathies

Approximately 10% of patients with peripheral neuropathy of otherwise unknown etiology have an associated monoclonal gammopathy. Both the neuropathies and the monoclonal gammopathies in these patients are heterogeneous, but several distinct clinical syndromes that may respond to specific therapies can be recognized. It is important to recognize these syndromes because monoclonal gammopathies also occur in 1% of the normal adult population, and in some cases, monoclonal gammopathies are coincidental and unrelated to the neuropathy. In patients with IgM monoclonal gammopathies, IgM M proteins frequently have autoantibody activity and are implicated in the pathogenesis of the neuropathy. IgM M proteins that bind to myelin-associated glycoprotein (MAG) have been shown to cause demyelinating peripheral neuropathy; anti-GM1 antibody activity is associated with predominantly motor neuropathy, and anti-sulfatide or chondroitin sulfate antibodies are associated with sensory neuropathy. The IgM monoclonal gammopathies may be malignant or nonmalignant, and polyclonal antibodies with the same specificities are associated with similar clinical presentations in the absence of monoclonal gammopathy. IgG or IgA monoclonal gammopathies are associated with neuropathy in patients with osteosclerotic myeloma or the POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy myeloma, and skin changes). Amyloidosis or cryoglobulinemic neuropathies can occur with either IgM or IgG and IgA monoclonal gammopathies. Therapeutic intervention depends on the specific clinical syndrome but is generally directed at removing the autoantibodies, reducing the number of monoclonal B cells, and interfering with the effector mechanisms.

Widenings of the myelin lamellae in a typical Guillain-Barré syndrome

The so-called "widening of the myelin lamellae" are thought to be specific ultrastructural features of peripheral nerve myelin in patients with peripheral neuropathy associated with a monoclonal dysglobulinemia of IgM type and antiglycolipid activity. We report here a case of Guillain-Barré syndrome with no evidence of serum monoclonal dysglobulinemia, presenting the typical widenings of the myelin lamellae in small-diameter myelinated fibers from a sural nerve biopsy. In view of the positive reaction with anti-C3d complement on direct immunofluorescence, an immunological mechanism may be involved in the widenings of the myelin lamellae.

Plasma-cell dyscrasia with polyneuropathy. The spectrum of POEMS syndrome

BACKGROUND

The POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome and osteosclerotic myeloma (polyneuropathy and sclerotic bone lesions) may both be manifestations of plasma-cell dyscrasia, but the interrelation of these diseases is not clear. We therefore set out to define the clinical spectrum of disease in patients with plasma-cell dyscrasia and polyneuropathy who have the complete or incomplete form of the POEMS syndrome or osteosclerotic myeloma.

METHODS

Among 2714 patients with plasma-cell dyscrasia who were identified between 1973 and 1989, we reviewed the cases of those with polyneuropathy and plasma-cell dyscrasia who fulfilled the criteria for the POEMS syndrome or osteosclerotic myeloma.

RESULTS

Thirty-eight patients (1.4 percent) with a median age of 51 years were identified, 22 of whom were male. By definition, all had polyneuropathy (37 combined sensorimotor, and 1 primarily motor). Other findings included osteosclerotic bone lesions (82 percent), skin abnormalities (58 percent), lymphadenopathy (42 percent), papilledema (37 percent), peripheral edema (29 percent), hepatomegaly (24 percent), splenomegaly (21 percent), and ascites (11 percent). Thirty-three patients (87 percent) had an abnormal M protein in serum or urine (17 had IgA lambda, and 12 IgG lambda). Five patients fulfilled all the criteria for the POEMS syndrome. The estimated five-year survival in the 38 patients was 60 percent, which was significantly better than the 20 percent survival in 869 patients with multiple myeloma (P < 0.05). The clinical course was similar among the patients with the complete form of the POEMS syndrome and those with the incomplete form.

CONCLUSIONS

Plasma-cell dyscrasia with polyneuropathy is a rare multisystem disease that often presents with osteosclerotic bone lesions. The differentiation of the POEMS syndrome from so-called osteosclerotic myeloma with peripheral neuropathy appears to have no clinical value.

The clinical spectrum of peripheral neuropathies associated with benign monoclonal IgM, IgG and IgA paraproteinaemia. Comparative clinical, immunological and nerve biopsy findings

Observations have been made on a consecutive series of 62 patients with peripheral neuropathy associated with benign monoclonal paraproteinaemia. The paraprotein class was IgM in 46 cases, IgG in 11 and IgA in 5. Although showing variations between patients, the clinical picture was similar for those with either IgM or IgG paraproteins, usually consisting of a late-onset, slowly progressive, distal sensorimotor demyelinating polyneuropathy, often with tremor and ataxia as prominent features. Tremor was slightly more common in patients with IgM paraproteins, in whom there was a male preponderance. The patients with both paraprotein classes were indistinguishable clinically and electrophysiologically from chronic idiopathic demyelinating polyneuropathy. In the 5 patients with an IgA paraprotein, there was a distal sensorimotor neuropathy in 4 which was demyelinating in 1. In 1 there was proximal demyelinating motor neuropathy. Immunoglobulin deposition on myelin was observed only in the patients with IgM paraproteinaemia, more commonly with a kappa light chain. No deposition of immunoglobulin in the endoneurium was seen. IgM deposits on the perineurium are a feature of normal nerve and were present in all cases. Widely spaced myelin was confined to cases with IgM paraproteins in which immunoglobulin deposition was detected on myelin. The response to treatment could not be assessed systematically but, in general, the patients with IgG and IgA paraproteins responded more satisfactorily (to corticosteroids, cytotoxic drugs, or plasma exchange) than did those with an IgM paraprotein.

Poems syndrome

A 40 year old Chinese woman presented with anasarca and later developed features of POEMS syndrome. These are peripheral neuropathy (P), organomegaly (O), endocrine dysfunction (E), monoclonal gammopathy (M), and skin changes (S) which are usually associated with plasma cell dyscrasia. In our patient, monoclonal gammopathy was not detected on immunofixation electrophoresis and was revealed only after analysis of kappa/lambda light chain ratio of the raised serum IgA immunoglobulin. Needle liver biopsy of her grossly enlarged liver showed marked accumulation of glycogen and presence of giant mitochondria in the hepatocytes, a feature not previously reported.

Axonal neuropathy with monoclonal IgG kappa that binds to a neurofilament protein

We report a 74-year-old woman with a slowly progressive sensory motor axonal neuropathy and a monoclonal IgG-kappa that bound to a 68-kd axonal protein identified as the low molecular weight neurofilament protein. The sera of control subjects and disease controls did not bind to neurofilament protein.

POEMS syndrome associated with polycythemia vera

POEMS syndrome is a multisystem disorder associated with polyneuropathy, organomegaly, endocrinopathy, a monoclonal protein (M-protein), and skin changes. The authors describe a patient with POEMS syndrome who has polyneuropathy of the upper and lower extremities, splenomegaly, impotence, IgA-lambda monoclonal protein (M-protein), and marked thickening of his skin. In addition, he has polycythemia vera. Although myeloproliferative disorders have been reported to occur in association with multiple myeloma, they have not been described with POEMS syndrome. The possible etiology of this association is discussed. This patient was successfully treated with melphalan and prednisone at the time of his initial diagnosis, but relapsed 10 years later. The relapse was treated with pulse doses of prednisone alone with complete resolution of his polyneuropathy and skin changes. This was accompanied by a fall in his IgA levels and improvement of his polycythemia.

AAEE case report #17: Peripheral neuropathy in monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is the most common paraproteinemia associated with polyneuropathy. Although the clinical and electrodiagnostic manifestations most resemble those of chronic inflammatory demyelinating polyneuropathy, some patients manifest a pure sensory neuropathy or neuronopathy. The M protein is usually IgM, and its concentration in serum is low. Nerve pathology from patients with demyelinating disease shows a reduction of large myelinated fibers and segmental demyelination with remyelination. In some cases, the M protein possesses antibody activity against components of the myelin sheath or axon. These neuropathies may respond to treatment with steroids, immunosuppressant agents, and plasma exchange.

Pathology of dysproteinemia: light chain amyloidosis, non-amyloid immunoglobulin deposition disease, cryoglobulinemia syndromes, and macroglobulinemia of Waldenström

This review has dealt with four syndromes associated with dysproteinemia, and has emphasized studies of the tissue deposits and forms of tissue injury which occur in such patients. However, similar tissue deposits and tissue damage occasionally occur in the absence of a serum or urine paraprotein, in which case other clinical data are necessary to suggest the need for examination of tissue for Ig heavy and light chain determinants in order to provide a correct diagnosis of dysproteinemia. In such cases, one may speculate that there is a low rate of paraprotein production and secretion, in addition to tissue tropism. Some paraproteins are antibodies, in which case they may circulate and/or deposit as immune complexes, or bind to tissue antigens with immune complex formation in situ. Some paraproteins are also cryoproteins, and clues to this property can also be found in the tissue, particularly at the ultrastructural level. Thus, a wide spectrum of clinical manifestations of a B cell proliferative disorder may be associated with any of a variety of circulating paraproteins and a variety of forms of tissue deposit and injury. Consequently, the best understanding of an individual patient requires correlation of the clinical features of the disorder, the immunochemical characterization of the circulating and excreted paraproteins, and an immunohistochemical analysis of the tissue deposits and associated morphologic abnormalities. This should be correlated with histologic and immunohistologic assessment of bone marrow, looking for overt B cell neoplasia, the more difficult to define "lymphoproliferative disorders," or alterations in kappa to lambda plasma cell ratios which may correlate with the deposited material. Studies of the Ig synthesized by cultured bone marrow plasma cells, and biochemical analyses of the deposited material, have demonstrated structural abnormalities of paraproteins which may be responsible for their tissue deposition.

POEMS syndrome associated with cryoglobulinemia, lymphoma, multiple seborrheic keratosis, and ichthyosis

The case of a patient with POEMS syndrome is presented. The characteristic features of the disorder were associated with the apparently unique and undescribed findings of multiple seborrheic keratosis, ichthyosis, livedo reticularis, and vasculitis, combined with IgM/IgG cryoglobulinemia. Analysis of the cryoprecipitate revealed monoclonal IgM, with kappa light chains. Six years later an immunoblastic lymphoma developed. Notably, the paraneoplastic cutaneous signs were present 6 years before the development of the immunoblastic lymphoma.

Autoimmunity in neuromuscular disease

A number of confounding factors can be identified from the search for autoimmune mechanisms over the last 2 decades that may be relevant for future studies. (1) An apparently homogeneous clinical disorder may represent more than one disease process and thereby imply antibody/antigen heterogeneity as, for example, in MG with and without detectable anti-AChR antibodies. In some cases, physiologic studies allow the different forms of the disease to be distinguished as in AIDP and acute inflammatory axonal polyneuropathy. (2) A homogeneous disorder (e.g., LEMS) may have at least two different triggering mechanisms (SCLC and an unknown stimulus). (3) Antigen density may be too low to be detected by the immunohistologic techniques available, as initially occurred in MG and LEMS. (4) Autoantibodies may be detected that are irrelevant to the primary disease, such as anti-striated muscle antibodies in MG. (5) Poor antibody cross-reactivity between species may mean that the pathogenic antibody is undetected in binding assays or in experimental passive transfer studies. For example, anti-AChR antibody in MG shows less than 5% reactivity with Torpedo AChR. (6) A poor regenerative capacity of the target antigen may mean that reduction of circulating autoantibodies by either plasma exchange or ISD treatment is not associated with detectable clinical improvement, as may be the case in SSN in which DRG cells appear to be the target. TABLE 5 summarizes the extent to which the data reviewed have established a role for pathogenic antibodies in the light of the postulates for autoimmunity set out earlier and ranks the disorders accordingly. Only in MG with detectable anti-AChR antibody are all the postulates met, including definition of the antigen, experimental passive transfer by the IgG fraction of MG sera, active immunization of experimental animals, and propagation. In both LEMS and the IgM kappa anti-MAG demyelinating neuropathy the antigen is known, although better characterized in LEMS; the epitopes are not yet defined in either. Data relating to passive transfer are more extensive in LEMS, however; systemic passive transfer of anti-MAG has not yet been reported. In neither condition is an animal model available. In the demyelinating neuropathies, the case for autoimmunity is less complete. Neither in AIDP nor in CIDP is the antigen known, and thus the relevance of the different EAN disorders is uncertain. Current evidence thus rests on the demonstration of serum IgM antibodies that react with peripheral nerve myelin and fix complement and on the intraneural passive transfer studies.(ABSTRACT TRUNCATED AT 400 WORDS)

The C57BL mice: an animal model for inflammatory demyelinating polyneuropathy

Recently it has been reported that the C57BL mice can be used as a model of benign monoclonal gammopathy (MG). Since experimental models have until now failed to reproduce specific lesions of human dysglobulinemic polyneuropathies, we decided to investigate the peripheral nerve of these mice. The sciatic nerve and the serum from 14 C57BL mice were examined: 9 of these animals were found to have an IgG, kappa light chain MG, while in the other 5 no abnormalities were detected in the serum. In the 14 mice, features of demyelination were found in certain fibers, as well as onion-bulb formations around other myelinated fibers. Features of active demyelination were found in 10 animals and it must be underlined that three of these had no serum abnormalities. The decrease of the conduction velocities and the temperature coefficients Q10 of the C57BL mice suggest a good correlation between morphological and functional parameters. This strongly suggests that this strain of mice provides a suitable model for inflammatory demyelinating polyneuropathy (IDPN).

Peripheral neuropathy associated with plasma cell dyscrasia: a clinical and electrophysiological follow-up study

Thirteen patients with polyneuropathy associated with plasma cell dyscrasia had serial electrophysiological studies. Five patients with monoclonal IgG had motor and/or sensory symptoms of which 4 correlated with slow motor and sensory nerve conduction. The 4 patients with monoclonal IgM reactive with myelin-associated glycoprotein (MAG), had predominantly motor symptoms, demyelination in the nerve biopsy and slow motor and sensory nerve conduction. Four patients with monoclonal IgM without anti-MAG activity had mainly sensory symptoms, axonal neuropathy on nerve pathology and slow or absent sensory nerve conduction. After treatment with plasmapheresis and chemotherapy 9 patients improved clinically and 4 were unchanged. Criteria for electrophysiologic improvement were presence of sensory or motor responses that were absent before treatment, conduction velocity increased by more than 10 m/s and increase of amplitude by more than 100%. Electrophysiological studies showed improvement in 7, were unchanged in 4, and worse in 2. Sensory velocities in ulnar and sural nerves were significantly improved following treatment (P less than 0.002) and the same trend was noted for the sensory velocity in the median nerve (P less than 0.19). We conclude that nerve conduction studies in combination with clinical examinations are useful in documenting the effects of treatment in these neuropathies.

Humoral factors in peripheral nerve disease

Humoral factors including soluble substances transported by the blood stream and factors released at a target tissue may play a role in diseases of the peripheral nervous system. Various criteria have to be met in order to accept humoral factors as potential pathogens. In this review these general criteria are discussed, including the evidence provided by plasma exchange therapy, demonstration of circulating or deposited autoantibodies and immune complexes, identification of antigenic molecules, animal model diseases, passive transfer experiments, and the demonstration of circulating factors not directed against specific targets. In acute, chronic, and chronic relapsing inflammatory polyneuropathies, and in the polyneuropathy associated with monoclonal gammopathy, humoral factors have been identified, but their exact pathogenic role is not fully understood. In the Lambert-Eaton myasthenic syndrome, a disorder of the motor nerve terminal, pathogenic IgG-antibodies have been demonstrated by passive transfer experiments. In the experimental animal model disorders, the acute and chronic variants of experimental allergic neuritis, humoral factors including antibodies to myelin basic proteins and galactocerebroside and nonspecific humoral factors may all contribute to the ultimate peripheral nerve damage, but their relative importance in relation to cell-mediated immune reactions is not yet clear.

Peripheral neuropathy associated with experimental plasma cell neoplasm in the mouse

In order to investigate the role of paraproteins in the production of neuropathy we experimentally induced monoclonal immunoglobulin-producing tumours into 32 BALB/c mice by injecting mineral oil or pristane intraperitoneally. In 11 mice morphologic and histometric studies of the sciatic nerve revealed the presence of neuropathy. Immunohistochemical studies did not demonstrate a significant amount of immunoglobulins and light chains in the endoneurium. The advantages and limits of this experimental model are discussed.

Polyneuropathy in Waldenström's macroglobulinaemia. Passive transfer from man to mouse

To support the hypothesis of an immunopathogenesis of polyneuropathy in Waldenström's macroglobulinaemia (MW), serum IgM fractions of MW patients were applied intraperitoneally to mice for 17 days. Sections of liver, kidney, M. glutaeus maximus, central nervous system (CNS) and both Nn. ischiadici were examined for IgM, IgG, C3 and as control IgD with PAP-immunostaining. IgM deposits were found in every organ except the CNS. In peripheral nerves larger amounts were visualized in perineurium and endoneural space, whereas myelin lamellae and periaxon did not stain. Therefore, perhaps our investigation reveals a greater permeability of the blood-nerve barrier (BNB) compared with the blood-brain barrier (BBB). The involvement of the monoclonal IgM of MW, which has been shown to react in vitro with peripheral nerve constituents, appears possible in the pathogenesis of polyneuropathy.

Benign monoclonal IgAK gammopathy associated with polyneuropathy and dysautonomia

The first case of benign IgAK monoclonal gammopathy associated with peripheral neuropathy is described. Dysautonomia is an unusual, yet prominent, manifestation of neuropathy in this patient. Electrodiagnostic testing and nerve biopsy were compatible with demyelination and axonal loss. Myelin sheath, perineural, and endoneural interstitial tissue fixation of anti-IgA and anti-kappa light chains was demonstrated by direct immunofluorescence microscopy. Absorption studies utilizing human peripheral nerve myelin resulted in complete removal of the paraprotein band. Analytic procedures with myelin-associated glycoprotein and gangliosides, however, were negative. Based on these findings, an alternative etiology for this neuropathy is hypothesized.

Peripheral neuropathy and monoclonal IgM with antibody activity against peripheral nerve myelin; effect of plasma exchange

Serum IgM antibodies directed against peripheral nerve myelin were demonstrated using enzyme-linked immunosorbent assay, mixed haemagglutination and indirect immunofluorescence in 3 patients with chronic polyneuropathy and monoclonal serum IgM. Isoelectric focusing followed by antigen immunofixation and autoradiography showed that the antimyelin antibodies co-migrated with the monoclonal IgM. Plasma exchange alone, without chemotherapy, proved beneficial in 2 patients. In one patient, plasma exchange was discontinued because of low IgG levels. Serum IgM and antimyelin antibodies decreased during plasma exchange and no increase beyond initial levels was noted after cessation of treatment.

POEMS syndrome. Study of a patient with proteinuria, microangiopathic glomerulopathy, and renal enlargement

We studied a patient with POEMS syndrome (plasma cell dyscrasia with polyneuropathy, organomegaly, endocrinopathy, monoclonal [M]-protein, skin changes) who was also found to have renal enlargement and microangiopathic glomerulopathy. The latter finding is unusual in POEMS syndrome patients, and the associated symptoms can lead to confusion in diagnosis. We emphasize the importance of considering POEMS syndrome in the differential diagnosis of patients who have unexplained neuropathy, scleroderma-like skin changes, and/or monoclonal gammopathy.

Passive transfer studies in demyelinating neuropathy with IgM monoclonal antibodies to myelin-associated glycoprotein

Serum or IgM fraction from two patients with a demyelinating neuropathy and IgM monoclonal antibodies to myelin-associated glycoprotein were injected in three different animal species. There were no clinical, electrophysiological or morphological signs of demyelination in either chronic or acute passive transfer experiments. These results suggest that the pathogenesis of this human demyelinating neuropathy may be more complex than has been assumed.

Polyneuropathy in paraproteinaemia

Paraproteinaemias are frequently associated with peripheral neuropathies. "Benign" paraproteinaemia, myeloma and Waldenströms macroglobulinaemia may present clinically as polyneuropathy. Therefore immunoelectrophoresis is strongly recommended in the routine diagnosis of polyneuropathies of unknown origin. Peripheral neuropathies associated with paraproteinaemia are clinically, electrophysiologically, pathologically and probably also pathogenetically heterogeneous. There are subgroups such as demyelinating neuropathy associated with IgM paraproteinaemia, which show quite distinctive features. This survey describes the different types of paraproteinaemia and their associated peripheral neuropathies. The incidence, pathogenesis and therapy of peripheral neuropathy associated with monoclonal gammopathies are discussed.

Reactivity of sera and isolated monoclonal IgM from patients with Waldenström's macroglobulinaemia with peripheral nerve myelin

Sera of 23 patients with Waldenström's macroglobulinaemia and six monoclonal IgM paraproteins, which had been isolated from these sera, were examined for reactivity against peripheral nerve tissue. Of these 23 patients, 12 had clinical signs of peripheral polyneuropathy (PN). Using an indirect immunofluorescence method, all sera and monoclonal IgM preparations reacted with peripheral nerve structures, displaying a distinct granular fluorescence pattern with anti-IgM sera. The Waldenström sera reacted mainly with structures at the border of the myelin sheath, as well as between myelin and axon, and occasionally with the axon itself. There was no difference between sera of patients with PN and those without. Negative results were obtained in a complement fixation assay. Of the 23 sera, 15 reacted in an antibody-dependent lymphocyte-mediated cytotoxicity reaction (ADLC) with peripheral nerve myelin, and to a much lesser extent with myelin basic protein from CNS. Five of the six isolated monoclonal IgM preparations also gave positive ADLC reactions. These results constitute additional evidence for an immunological mechanism in the pathogenesis of PN in Waldenström's macroglobulinaemia.

Peripheral neuropathies associated with monoclonal proteins: a clinical review

Over the last decade, the increasing use of serum and urine protein electrophoretic screening of patients with idiopathic peripheral neuropathy has led to greater recognition of peripheral neuropathy syndromes that are associated with monoclonal proteins and plasma cell dycrasias. After careful evaluation, most of these patients have benign monoclonal gammopathy, followed in frequency by primary systemic amyloidosis and osteosclerotic myeloma, with occasional cases associated with osteolytic multiple myeloma, Waldenstrom's macroglobulinemia, gamma heavy chain disease, and other rare disorders. Several of these syndromes have distinctive presentations and are recognizable clinically, whereas others (especially multiple myeloma neuropathy) are diverse clinically and are not clearly distinguishable from other chronic neuropathies. The discovery of IgM-kappa monoclonal proteins directed at myelin antigens in some patients with benign monoclonal gammopathy and the delineation of the syndrome of neuropathy and multiorgan involvement in osteosclerotic myeloma are important developments which may shed light on the mechanism of the remote effects of malignancies on the nervous system.

Paraproteinemia associated with demyelinating polyneuropathy or myositis: treatment with plasmapheresis and immunosuppressive drugs

Four patients with chronic, progressive demyelinating peripheral polyneuropathy were found to have paraproteinemia. Two of the patients had multiple myeloma [both immunoglobulin (Ig)G lambda]. The other two had benign gammopathies: one of IgG kappa type and the other one with marked polyclonal elevation of IgM. Immunofluorescence studies revealed deposits of the abnormal serum immunoglobulin along the myelin sheaths in two of the patients in whom sural nerve biopsies were performed. All four patients were treated with plasmapheresis in combination with immunosuppressive drugs. Favorable responses to the therapy was observed in all four patients, but the degree of response varied from patient to patient. Two patients who presented clinical and electromyographic findings consistent with polymyositis were found to have serum IgG kappa M components. Immunofluorescence studies performed on muscle biopsy material from both patients revealed deposits of the abnormal serum paraprotein along the sarcolemmal basement membrane. A treatment course of plasmapheresis and immunosuppressive drugs resulted in a sustained increase of muscle strength in both patients.

Therapeutic trial of plasma exchange in osteosclerotic myeloma associated with the POEMS syndrome

A patient with osteosclerotic myeloma and POEMS syndrome, unresponsive to pulse prednisone and melphalan therapy, was admitted to the hospital for a trial of plasma exchange therapy. The presentation included IgG lambda monoclonal gammopathy, peripheral neuropathy, hepatosplenomegaly, hyperpigmentation and thickening of the skin, edema, and tense ascites. Laboratory tests confirmed hypothyroidism, hypogonadism, and adrenal insufficiency. Six exchange procedures failed to affect the clinical course, and the patient died. Greater-than-one-plasma-volume exchanges (patient's measured plasma volume, 2,703 cc) were performed. When IgG and cholesterol removal were compared to the predicted removal, based on the volume of plasma removed, significantly less reduction in concentration than predicted was measured. IgG concentrations increased postapheresis and, at 2 weeks, three-fourths of the removed IgG had reaccumulated. A reduced efficiency of removal of both IgG and cholesterol can be explained by postulating increased vascular permeability with free exchange of soluble substances from one compartment to another. If an abnormal product is produced by the disease and is responsible for the clinical syndrome, a more intensive schedule of plasma exchange therapy may be needed to achieve a sustained depletion of the responsible soluble substance. Alternatively, neither increased vascular permeability or the clinical manifestations are responsive to removal of a soluble substance or are caused by a soluble substance produced by the malignancy.

The mouse blood-brain barrier and blood-nerve barrier for IgG: a tracer study by use of the avidin-biotin system

To study the permeability of the blood-brain barrier (BBB) and the blood-nerve barrier (BNB) for immunoglobulin G (IgG) we adapted the avidin-biotin system for postembedding demonstration of the tracer IgG in the central and peripheral nervous system (CNS, PNS). Normal mouse and human IgG were biotinylated and injected daily into the intraperitoneal (i.p.) space of adult BDF1 mice. After 24h, IgG was detected in blood vessels and in the interstitium of various organs, but staining was restricted to the dura mater in the CNS, to the spinal ganglia, and to the perineurium of peripheral nerves. After 4 days, IgG was also present in the endoneurial connective tissue of peripheral nerves, while the brain, spinal cord, and spinal roots remained free of IgG. Our results show a partial permeability of the normal mouse BNB for homologous and heterologous IgG.

Chronic inflammatory polyneuropathy. Reduction of nerve conduction velocities in monkeys by systemic passive transfer of immunoglobulin G

In chronic (relapsing) inflammatory polyneuropathy (CRIP), successful treatment with plasma exchange has led to the concept of pathogenic humoral factors. In 6 patients with CRIP, 5 of whom improved after plasma exchange, the potential pathogenic role of circulating immunoglobulin (Ig) fractions was tested by applying the systemic passive transfer model to marmoset monkeys. After continuous treatment with intramuscular injections for 2-8 weeks, monkeys injected with the crude immunoglobulin fractions or with purified IgG from 5 of the 6 patients showed a significant and partially reversible reduction of the motor nerve conduction velocity (mean 34%, P less than 0.001) when compared with pre-treatment values. In control animals the reduction was 4%. Morphological examination revealed only minor ultrastructural changes of the myelin sheath. Immunocytochemistry revealed that human IgG was able to cross the blood-nerve barrier. It is concluded that the circulating IgG-fraction of patients with CRIP contains a factor that may contribute to the disordered nerve function after crossing the blood-nerve barrier. It may be the removal of this particular factor which is responsible for the rapid recovery of nerve conduction in patients after plasma exchange.

Plasma exchange treatment of peripheral neuropathy associated with plasma cell dyscrasia

Plasma exchange was used to treat 10 patients with polyneuropathy and a monoclonal antibody (plasma cell dyscrasia). Six patients had improvement of the neuropathy, while three patients had stabilisation of the neuropathy during plasma exchange. The patients who improved maintained a 64% or greater decrease in the monoclonal antibody between exchanges. Patients with axonal polyneuropathy as well as patients with demyelinating polyneuropathy recovered some neurologic function. With cessation of plasma exchanges, the monoclonal antibody titre approached pre-treatment levels and the neuropathy progressed. Plasma exchange was effective in rapidly lowering the level of monoclonal antibody and allowing for some recovery of neurologic function.

IgM demyelinative neuropathy with amyloidosis and biclonal gammopathy

A 59-year-old man developed a sensorimotor neuropathy of the upper and lower limbs, associated with a biclonal gammopathy, within the space of a few months. Each of two paraproteins was coupled with a distinct IgM kappa IgG lambda light chain. Examination of a nerve biopsy specimen by electron microscopy revealed a demyelinative process with a widening of the interlaminar space in the myelin sheath, as well as deposits of amyloid substance between nerve fibers. Direct immunofluorescence revealed the presence of IgM and of the kappa light chain in certain Schwann cells, while the lambda IgG was fixed to the amyloid deposits. Immunoperoxidase histochemistry showed a positive reaction in normal human nerve tissue to the immune serum IgM and kappa light chain. The findings suggest that the widening of the interlaminar space of the diseased myelin corresponds to an active fixation of immunoglobulin on the sheath of the Schwann cell. The presence of two light chains in this patient's gammopathy caused a dual pathology: the kappa chain, a demyelinative neuropathy, and the lambda chain, a primary amyloidosis, with deposits in the peripheral nerve and in the kidney.

Primary and secondary cardioneuropathies and their functional significance

For most functions of the heart its nerves are as important as its coronary arteries, but this is particularly true concerning cardiac rhythm, conduction and repolarization. It is thus paradoxical that postmortem correlative studies of sudden death virtually always include careful scrutiny of the coronary arteries but only rarely of the cardiac nerves or ganglia. In this review, abnormalities of the cardiac nerves and ganglia, collectively termed cardioneuropathies, are examined from the dual standpoint of their structural appearance and functional significance. Some cardioneuropathies are found in the absence of any other significant structural abnormality detectable in the heart and these are designated as primary cardioneuropathies. A viral etiology or some heritable disorder must rank high among possible causes. Secondary cardioneuropathies are those observed in association with almost every disease that can affect the heart; examples include myocardial infarction, infections, amyloidosis and cancer, but there are many others. Because abnormalities of the heart's nerves and ganglia not only have their own unstabilizing influence on cardiac electrical activity but can also profoundly alter a patient's responses to pharmacologic treatment, it is hoped that future clinicopathologic examinations will more often include their careful study and thereby add to our meager knowledge about these important structures.

Abnormal serum factors in Guillain-Barré syndrome

The Guillain-Barré Syndrome (GBS) is generally considered to be a cell-mediated immunopathologic disease of the peripheral nervous system (PNS), although the evidence for this is indirect. Both in vitro and in vivo studies of sera from experimental animals with autoimmune demyelinating neuropathies suggest that serum factors, including antibodies to PNS myelin and/or Schwann cells, may be important in the pathogenesis of some of these disorders. More recently, similar in vitro and in vivo techniques, including the production of demyelination following intraneural injection in the rat have been employed to study sera from patients with GBS. The results of these studies demonstrate the presence of factor(s), as yet not fully characterized, that may be important in mediating demyelination. Moreover, in some patients with chronic or relapsing demyelinative inflammatory neuropathies and monoclonal gammopathy, there is evidence of antimyelin antibodies to PNS myelin. Further studies of serum from patients with acute GBS and these other neuropathies may clarify the role of serum factors in acquired inflammatory diseases of the PNS.

IgM paraproteins with immunological specificity for a Schwann cell component and peripheral nerve myelin in patients with polyneuropathy

The sera of 9 patients with benign IgM paraproteinaemia and chronic sensorimotor neuropathy were tested for reactivity to human peripheral nerves by the indirect immunoperoxidase method. They reacted in very high titre (10(-3)-10(-6) with a cytoplasmic Schwann cell component, and to lesser degree, with peripheral nerve myelin (10(0)-10(-3). The Schwann cell staining was in the form of perinuclear cytoplasmic granules and was only seen with adult nerve. The distribution of the antigen was similar to that of the metachromatically staining Pi-granules of Reich, which accumulate in the peripheral nerves with age. Specific activity was present in the IgM and F(ab)2 fractions and could be absorbed out with peripheral nerve tissue, but not with liver. Reactivity is not a simple function of the IgM level, since many IgM paraproteins do not react. The antibody is species specific and binds to human, but not to any component of rabbit, rat or guinea pig sciatic nerves. Antigenicity is removed by pretreatment of the nerve with chloroform-methanol or periodate, but not protease or trypsin. Reactivity is restored, after periodate treatment, by exposure to sodium borohydride. It is suggested that some IgM paraproteins have a specificity for a myelin glycolipid or glycoprotein, which normally accumulates in the Pi-granules of the Schwann cell cytoplasm as a function of age.

Neuropathy accompanying IgM lambda monoclonal gammopathy

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.