Anti-myelin-associated glycoprotein IgM antibody titers in neuropathy associated with macroglobulinemia

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)

Chronic idiopathic polyneuropathy presenting in middle or old age: a clinical and electrophysiological study of 75 patients

The clinical and electrophysiological features were prospectively studied of 75 patients (46 men and 29 women) with chronic polyneuropathy presenting in middle or old age in whom a diagnosis could not be made even after extensive evaluation and a follow up of six months. The mean age at the onset of symptoms was 56.5 years. The clinical features of chronic idiopathic polyneuropathy are heterogeneous. On clinical grounds 44 patients had a sensorimotor, 29 patients a sensory, and two patients a motor polyneuropathy. The overall clinical course in chronic idiopathic polyneuropathy was slowly progressive. None of the patients became severely disabled. Electrophysiological and nerve biopsy studies were compatible with an axonal polyneuropathy. Antibodies against myelin associated glycoprotein, gangliosides, and sulphatides were assessed in 70 patients and found to be negative.

Delayed appearance of anti-myelin-associated glycoprotein antibodies in a patient with chronic demyelinating polyneuropathy

A patient who had a polyneuropathy compatible with a chronic inflammatory demyelinating polyneuropathy and was initially negative for anti-myelin-associated glycoprotein (MAG) antibodies developed a double monoclonal gammopathy, IgM kappa and IgM lambda, two years after the diagnosis. The IgM kappa, but not the IgM lambda, exhibited strong anti-MAG antibody activity. The late appearance of the anti-MAG immunoreactivity suggests that in patients with an initial diagnosis of chronic inflammatory demyelinating polyneuropathy, the search for anti-MAG antibodies should be repeated during the course of the neuropathy.

Peripheral neuropathy associated with monoclonal IgM antibody to glycolipids with a terminal glucuronyl-3-sulfate epitope

Twenty-nine patients with paraproteinaemia, 12 with neuropathy and 17 without a previous record of neurological symptoms were clinically characterized. All 12 neuropathy patients had a moderate to severe sensorimotor demyelinating neuropathy. The patients were examined with regard to serum antibodies to gangliosides, including GM1, GD1a, GD1b, GT1b, and LM1, and other acidic glycolipids, including LK1 and sulphatide, of human brain and peripheral nerve. Sera from 80 blood donors, 40 men and 40 women 20-60 years of age, were used as normal controls. The sera were analysed with an ELISA performed on thin-layer chromatography plates. At a dilution of 1/400 none of the control sera gave a detectable reaction and a titre of > or = 1:400 was considered as a positive test. In 11 of the 12 neuropathy patients the paraproteinaemia was of IgM type and 10 of them had a positive antibody titre against LK1 and Hex-LK1, acidic glycolipids with a terminal glucuronyl-3-sulphate group. The antibody titre against LK1 in 1 patient was 1:400 and varied between 1:5,000 and 1:3,200,000 in the other 9. One of the patients also had a positive titre, 1:64,000, to sulphatide. None of the sera from the 17 paraproteinaemia patients without a previous record of neurological symptoms contained antibodies to LK1 or to any glycolipid antigen examined, except for sulphatide. A positive titre (> or = 1:400) of antibodies to sulphatide was found in sera from 4 of these patients, the titres being < or = 3,200.(ABSTRACT TRUNCATED AT 250 WORDS)

Susceptibility to demyelinating polyneuropathy in plasma cell dyscrasia may be influenced by amino acid position 9 of the HLA-DR beta chain

Fifty-five patients with plasma cell dyscrasias were investigated by genomic typing for HLA-DR and -DQ genes by restriction fragment length polymorphism, neurophysiology and for presence of anti-myelin-associated glycoprotein (MAG) antibodies. In 26 patients, a polyneuropathy (PN) of demyelinating type was established. Among these individuals, an association was found with the presence of a tryptophan amino acid residue at position 9 of the DR beta chain (P < 0.01). This position is part of the first hypervariable region of the DR beta chain, and may be of importance in determining preferential peptide-binding capacity of the HLA-DR molecule. The presence of anti-MAG antibodies in 15 out of 17 patients with an IgM M-component and demyelinating PN (14 of these 15 individuals carrying a tryptophan at position 9) supports the pathogenic role of an autoimmune response against MAG. The finding of an HLA class II association may indicate a pathogenic role of T cell immunity in this condition.

Immunoelectron microscopic localization of monoclonal IgM antibodies in gammopathy associated with peripheral demyelinative neuropathy

A sural nerve biopsy from a patient with benign monoclonal IgM kappa gammopathy and sensory-motor demyelinative neuropathy, revealed marked loss of myelinated fibers and focal axonal degeneration as well as widespread demyelination and remyelination with onion-skin formation. Almost all myelinated fibers displayed characteristic widening of the myelin lamellae as well as excessive thickness and/or exuberant outfoldings of myelin, reminiscent of that seen in tomaculous neuropathy. Many endoneurial capillaries were lined by fenestrated endothelium, indicating breakdown of a normal blood-nerve barrier. The endoneurium contained large amounts of extracellular proteinaceous material. Immunofluorescence and immunoelectron microscopy performed on the nerve of the patient, demonstrated selective deposition of IgM kappa gammaglobulin, exclusively in the areas of splittings of the myelin lamellae. Schwann cells contained cytoplasmic myelin debris labelled with IgM kappa only. In the indirect immunofluorescence and immunoelectron microscopy, serum of the patient reacted with the whole thickness of compact peripheral myelin of a normal human nerve. There was no immunoreactivity with the central myelin, Schwannoma cells, glial cells, axons or neurons. Demonstration of the selective presence of monoclonal IgM in widened lamellae of myelinated fibers, as well as bound to the internalized myelin debris in Schwann cells and macrophages, indicates a pathogenetic role of monoclonal paraprotein in myelin injury. Demyelination is promoted by development of endothelial fenestrations in the endoneurial capillaries and breakdown of the blood-nerve barrier.

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.

Peripheral neuropathy in monoclonal gammopathy of undetermined significance: prevalence and immunopathogenetic studies

In an unselected series of patients with monoclonal gammopathy of undetermined significance (MGUS) we found neuropathy in 2 of 34 patients with IgG (6%), 2 of 14 with IgA (14%), and 8 of 26 with IgM MGUS (31%). The neuropathy was subclinical in 6 patients (1 IgG, 1 IgA, and 4 IgM). Patients with IgG or IgA MGUS had a prominent motor impairment with electrophysiologic and morphologic findings suggestive of predominant axonal degeneration. No deposit of the M-protein in sural nerve and no reactivity of the M-protein with nerve was detected in these patients. Patients with IgM MGUS had a prominent sensory impairment with evidence of predominant demyelination. In 6 of these patients the M-protein reacted with the myelin-associated glycoprotein (MAG). The higher prevalence of neuropathy in patients with IgM MGUS may be related to the frequent reactivity of IgM M-proteins with MAG.

The structure of two IgMs showing different activity from a patient with Waldenstrom's macroglobulinaemia

The two monoclonal IgMs (IgM1 and IgM2) were characterized from a patient Waldenström's macroglobulinaemia that resulted in a gammapathy. Heavy and light chains were isolated from the IgM. The complete primary structure of the two light chains and the NH2-terminal region of the two heavy chain molecules were determined. The sequence data indicated that the heavy and light chains from both IgMs belong to the same (III and II) lambda subgroups. By testing their antibody activity it was found by immunofluorescence and immunoblotting that only IgM2 reacts with an intermediate filament protein.

A clinical, electrophysiological, morphological and immunological study of chronic sensory neuropathy with ataxia and paraesthesia

We have observed 9 patients (8 men and 1 woman), 58 to 77 years of age with neuropathy with only sensory symptoms and insidious onset. Five of them (4 men and 1 woman) aged 65 to 77 years, had normal serum electrophoretic profiles, while the others (all men), 58 to 74 years, had IgM monoclonal gammopathy of undetermined significance (MGUS). Clinical data were consistent with a sensory neuropathy affecting predominantly the kinesthetic sense (position and vibration sensation). The electrophysiological data indicated predominant sensory axonal neuropathy. Morphological data confirmed the primary axonal damage. Western immunoblot showed that the IgG from a patient without MGUS reacted with a 55 kD protein of dorsal root ganglion homogenate. Three of four patients with IgM MGUS were serum reactive against chondroitin sulfate C (ChS-C) in double immunodiffusion. After absorption with ChS-C the monoclonal peak completely disappeared from two patients and was decreased in the third patient. Our data indicate that immunological abnormalities are part of the pathogenesis for a subgroup of chronic neuropathy with only sensory symptoms.

DNA sequence analysis and comparison of the variable heavy and light chain regions of two IgM, monoclonal, anti-myelin associated glycoprotein antibodies

The complete variable heavy and light chain gene sequences of two monoclonal, IgM, anti-myelin associated glycoprotein (MAG) antibodies associated with peripheral neuropathy, are presented. Comparative analysis of the two VH regions has revealed that they are 88% homologous to one another and are both members of the VH3 gene family. They are also highly homologous to a gene which is frequently utilized in the fetal B-cell repertoire. The V kappa light chain gene of one of the antibodies is 99% homologous to a V kappa II gene and the V lambda light chain gene of the other antibody is only 72% homologous to other known V lambda genes. Further analysis of V genes utilized by anti-MAG antibodies should reveal the structural basis for their binding activity.

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.

Motor neuron disease in a patient with a monoclonal IgMk directed against GM1, GD1b, and high-molecular-weight neural-specific glycoproteins

In a patient with motor neuron disease and benign IgMk monoclonal gammopathy, the M protein reacted with the glycolipids GM1, GD1b, and asialo GM1 and, by immunoblot, with some high-molecular-weight neural-specific glycoproteins. The main reactive bands had an approximate molecular weight of 250 and 400 kd, were most concentrated in the spinal cord, and were also bound by the lectin peanut agglutinin. The presence of the Ga1(beta 1-3)Ga1NAc epitope on these neural-specific glycoproteins may help to explain the selective neurological impairment of the patient.