title: Immunofixation superior to plasma agarose electrophoresis in detecting small M-components in patients with polyneuropathy.
abstract: 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)
authors.affiliation: Department of Neurology, University Hospital of Linköping, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Vrethem
authors.forename: B
authors.initials: B
authors.lastname: Larsson
authors.forename: H
authors.initials: H
authors.lastname: von Schenck
authors.forename: J
authors.initials: J
authors.lastname: Ernerudh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004587:Electrophoresis, Agar Gel / Q000379:methods; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000097:blood / Q000276:immunology; D009422:Nervous System Diseases / Q000097:blood / Q000209:etiology / Q000276:immunology*; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M