Immunohistochemical localization of cytokines, C5b-9 and ICAM-1 in peripheral nerve of Guillain-Barré syndrome.

The spectrum of the Guillain-Barré Syndrome (GBS) has recently been widened by the newly identified forms of acute motor axonal neuropathy (AMAN) and acute motor sensory axonal neuropathy (AMSAN). An important question has been raised regarding the possibility for the axon to be a target in immune-mediated damage. Although myelin breakdown is the characteristic feature of classic acute inflammatory demyelinating polyradiculoneuropathy (AIDP), axonal degeneration may occasionally be observed in this form, especially in cases with explosive onset and severe clinical course. Immunohistochemical findings of five frozen sural nerves biopsies of patients with GBS (AIDP variant) tested with a panel of monoclonal antibodies raised against different molecules implicated in immune-mediated processes have principally disclosed an immunoreactivity of tumor necrosis factor-alpha (TNF-alpha) on both Schwann cell membranes and in myelinated and unmyelinated axons. On the other hand, interleukin 1-beta (IL1-beta) labeled Schwann cells, endothelial cells and macrophages; interferon-gamma (IFN-gamma) was observed both in endothelial cells and lymphocytes. Membrane attack complex (C5b-9) deposits were observed on Schwann cell membranes and finally intercellular adhesion molecule-1 (ICAM-1) was localized both on endothelial cells and macrophages. Our findings strongly suggest that TNF-alpha is an important factor in the cascade of events leading to immune-mediated demyelination and axonal damage in GBS.

Adult onset reducing body myopathy.

We report the case of a 28 year-old woman with left scapuloperoneal syndrome since the age of 24. The course was slowly progressive and diffuse weakness was observed 4 years later. Serum creatine kinase levels were moderately elevated (x3 normal value) and EMG showed mixed neurogenic and myogenic patterns. Muscle biopsy showed type I predominance and numerous reducing bodies in muscle fibers. Reducing bodies were strongly immunoreactive with antibodies to dystrophin, alpha-sarcoglycan, vimentin and ubiquitin. Desmin immunoreactivity was increased at the periphery of some reducing bodies but alphaB crystallin, alpha actinin, titin and nebulin were negative. Western blot analysis showed an increase in dystrophin, vimentin and desmin expression. Ultrastructurally, reducing bodies were composed of tubulofilamentous material, 17 nm in diameter, and immunoreactive with anti-Dys 2 antibody. Granulofilamentous material, immunoreactive with anti-desmin antibody was observed at the periphery of some reducing bodies. This report further highlights the proteinic composition of reducing bodies and shows that late onset reducing body myopathy may occur.

Exertional rhabdomyolysis and exercise intolerance revealing dystrophinopathies.

Exercise intolerance associated with myalgias, muscle cramps or myoglobinuria may be associated with a dystrophinopathy. A search for abnormal dystrophin expression (using immunohistochemistry, immunoblot and DNA analysis) was carried out in a series of 15 patients. They were selected because they presented exercise intolerance, negative biochemical tests (lipid, glycogen and mitochondrial metabolism) and abnormal immunohistochemistry with at least one anti-dystrophin antibody (anti-Dys 1, rod domain; anti-Dys 2, C terminus; anti-Dys 3, N terminus). Lack of anti-Dys 1 immunoreactivity was seen in three patients and abnormal immunoreactivity with all three anti-dystrophin antibodies in two. Immunoblot confirmed the dystrophinopathy in these five patients only, and multiplex polymerase chain reaction DNA analysis revealed a deletion in the dystrophin gene in two of these patients, affecting the proximal part of the rod domain in one and the distal part of this domain in the other. The clinical, biological and histopathological features of the five patients reported here, together with the previous cases reported in the literature, are described and reveal that exercise intolerance associated with dystrophinopathy displays characteristic clinical, biological and immunohistochemical features and defines a new dystrophinopathy phenotype. The absence of staining in the rod domain provides a secure diagnosis of this syndrome. Dystrophinopathy is one etiology of idiopathic myoglobinuria, requiring genetic counseling.

Acquired multifocal myofibrillar disruption selective of type II fibres.

We report three cases of patients who complained of myalgia showing histological features similar to tubular aggregates in their muscle biopsies. All had an elevated erythrocyte sedimentation rate without any evidence of infectious or autoimmune disease. On electron microscopy, small areas of myofibrillar degeneration, selectively in type II fibres, were found in all patients, but no tubular aggregates were seen. Although the pathogenesis of these lesions is unclear, it does seem that this condition is acquired and transient.