Affinity immunoblotting detection of serum monoclonal immunoglobulins reactive with glycosphingolipids

In vitro induction of neuronal apoptosis by anti-Fas antibody-containing sera from amyotrophic lateral sclerosis patients

Sera from 26% of patients with sporadic amyotrophic lateral sclerosis (ALS) induced in vitro apoptosis of a human neuroblastoma cell line, as detected by two methods, and most contained anti-Fas autoantibodies. In contrast, Alzheimer sera (studied as controls) very rarely induced apoptosis and did not contain detectable anti-Fas antibodies. Soluble Fas-ligand levels in ALS sera were not different from those in normal sera, except for slightly higher levels in a single case. In mixed cultures of rat embryonic brain and spinal cord cells, ALS sera (and agonistic anti-Fas monoclonal antibodies and soluble Fas-ligand) induced the apoptosis of a subpopulation of neurons. These neurons were motoneurons on the basis of staining with the monoclonal antibody SMI 32 and Fas expression was restricted to these SMI 32-positive neurons. These data are compatible with the hypothesis of the participation of an autoimmune mechanism possibly related to anti-Fas autoantibodies in certain ALS patients.

[IgM kappa lymphoma with antisulfatide antibodies revealed by cervical motor neuropathy simulating amyotrophic lateral sclerosis]

INTRODUCTION

It is well known that polyneuropathy is associated with monoclonal IgM kappa.

EXEGESIS

We report the case of a 79-year-old man with lymphoma and motor neuron disease at cervical level simulating amyotrophic lateral sclerosis (ALS). Neurological deficit with inflammatory process evolved within 4 months. Electrophysiological findings showed increased and enlarged muscular potentials with neurogenic patterns. Nerve conduction velocities were normal, with neither multifocal neuropathy nor persistent conduction blocks. Besides mixed cryoglobulinemia type II, antisulfatide antibodies issued from monoclonal IgM were found. They were directed against myelin glycosphingolipids. No antiganglioside GM1 antibodies could be detected. This not only evoked ALS but also proximal motor axonopathy related with monoclonal IgM.

CONCLUSIONS

This case suggests that antisulfatide antibodies often present in sensitive demyelinating polyneuropathy could also be involved in lower motor neuron syndrome.

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.

Link between peripheral neuropathy and monoclonal dysglobulinemia: a study of 66 cases

The association of peripheral neuropathy (PN) and monoclonal dysglobulinemia has often been reported, although a direct link between the two is not readily established. Linkage is generally based on consideration of the clinical, electrophysiological and immunological findings along with details of the course. We report here a study of 66 of our own cases which benefitted from immunological and immunopathological analyses of serum. In 62 of these cases, histological and immunopathological examinations of nerve biopsy specimens were realized. Such a discussion about a link between the dysglobulinemia and the peripheral neuropathy is of clinical interest as it provides information for decisions about the continuation of potentially neurotoxic chemotherapy. In this prospective study conducted on a case by case basis, the origin of the neuropathy, whether due to the chemotherapy, the dysimmune process, the presence of abnormal immunoglobulins in the nerve, amyloid deposits, infiltration of nerve parenchyme by abnormal cells, or a combination of one or more of these mechanisms, could be determined in most cases. We divided our population of 66 patients into 4 etiological groups: group 1: direct link (56.1%), group 2: indirect link (12.7%), group 3: no link (10.6%), group 4: doubtful link (21.2%). In group 1 we found a statistically significant association between the peripheral neuropathy and an IgM kappa MGUS.

Monoclonal IgM reactive with several gangliosides in a chronic relapsing polyneuropathy

A possibly pathogenic serum monoclonal IgM lambda from a patient with chronic relapsing polyneuropathy was shown to react with the disialosyl-lactosyl residue (NeuAc alpha 2-8NeuAc alpha 2-3) -Gal beta 1-4Glc expressed by GD1b, GT1b, GQ1b, GD2 and GD3. A part of this epitope in terminal position in GM3, GD1a and LM1 was also recognized by the IgM lambda.

Reactivity of a human monoclonal anti-GM1 and anti-GD1b IgM antibody with human neurons in cultures

A serum containing a monoclonal IgM lambda with anti-GM1 and anti-GD1b activity was obtained from a patient with upper motor neuron syndrome. By indirect immunocytochemical techniques with double staining, the patient's IgM strongly stained membranes of neurons in primary cultures of fetal central and peripheral nervous system. It was cytotoxic for neurons in two human neuroblastoma established cell lines in a complement-dependent chromium release assay. These results are in keeping with the hypothesis of a direct pathogenetic role of such monoclonal anti-GM1 and GD1b IgM antibodies.

A filter affinity transfer method for the analysis of rheumatoid factors

Transfer of serum proteins separated by thin layer agarose electrophoresis onto nitrocellulose sheets precoated with purified human polyclonal IgG followed by revelation with enzyme-coupled anti-mu or anti-alpha antisera resulted in the specific detection of rheumatoid factors (RF) belonging to the IgM or IgA classes. Mono- or polyclonality of such RF can be evaluated from the patterns of the blots (sharp bands). In addition, their light chain type can be determined using affinity filters coated with a gamma heavy chain disease protein or with IgG Fc fragments. This simple and rapid procedure allows an easy characterization of monoclonal RF, even if they are present in minute amount amongst polyclonal RF as in certain sera from rheumatoid arthritis patients.