Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy

Introduction: Paraneoplastic autoantibody screening of 150,000 patient sera by tissue‐based immunofluorescence incidentally revealed 170 with unsuspected signal recognition particle (SRP) immunoglobulin G (IgG), which is a recognized biomarker of autoimmune myopathy. Of the 77 patients with availab...

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Main Authors:	Apiwattanakul, Metha, Milone, Margherita, Pittock, Sean J., Kryzer, Thomas J., Fryer, James P., O'toole, Orna, Mckeon, Andrew, Lennon, Vanda A.
Format:	Online
Language:	English
Published:	John Wiley and Sons Inc. 2016
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5067628/

id	pubmed-5067628
recordtype	oai_dc
spelling	pubmed-50676282016-11-01 Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy Apiwattanakul, Metha Milone, Margherita Pittock, Sean J. Kryzer, Thomas J. Fryer, James P. O'toole, Orna Mckeon, Andrew Lennon, Vanda A. Clinical Research Introduction: Paraneoplastic autoantibody screening of 150,000 patient sera by tissue‐based immunofluorescence incidentally revealed 170 with unsuspected signal recognition particle (SRP) immunoglobulin G (IgG), which is a recognized biomarker of autoimmune myopathy. Of the 77 patients with available information, 54 had myopathy. We describe the clinical/laboratory associations. Methods: Distinctive cytoplasm‐binding IgG (mouse tissue substrate) prompted western blot, enzyme‐linked immunoassay, and immunoprecipitation analyses. Available histories were reviewed. Results: The immunostaining pattern resembled rough endoplasmic reticulum, and mimicked Purkinje‐cell cytoplasmic antibody type 1 IgG/anti‐Yo. Immunoblotting revealed ribonucleoprotein reactivity. Recombinant antigens confirmed the following: SRP54 IgG specificity alone (17); SRP72 IgG specificity alone (3); both (32); or neither (2). Coexisting neural autoantibodies were identified in 28% (low titer). Electromyography revealed myopathy with fibrillation potentials; 78% of biopsies had active necrotizing myopathy with minimal inflammation, and 17% had inflammatory myopathy. Immunotherapy responsiveness was typically slow and incomplete, and relapses were frequent on withdrawal. Histologically confirmed cancers (17%) were primarily breast and hematologic, with some others. Conclusions: Autoimmune necrotizing SRP myopathy, both idiopathic and paraneoplastic, is underdiagnosed in neurological practice. Serological screening aids early diagnosis. Cancer surveillance and appropriate immunosuppressant therapy may improve outcome. Muscle Nerve 53: 925–932, 2016 John Wiley and Sons Inc. 2016-02-05 2016-06 /pmc/articles/PMC5067628/ /pubmed/26561982 http://dx.doi.org/10.1002/mus.24970 Text en © 2015 The Authors. Muscle & Nerve Published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs (http://creativecommons.org/licenses/by-nc-nd/4.0/) License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Apiwattanakul, Metha Milone, Margherita Pittock, Sean J. Kryzer, Thomas J. Fryer, James P. O'toole, Orna Mckeon, Andrew Lennon, Vanda A.
spellingShingle	Apiwattanakul, Metha Milone, Margherita Pittock, Sean J. Kryzer, Thomas J. Fryer, James P. O'toole, Orna Mckeon, Andrew Lennon, Vanda A. Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy
author_facet	Apiwattanakul, Metha Milone, Margherita Pittock, Sean J. Kryzer, Thomas J. Fryer, James P. O'toole, Orna Mckeon, Andrew Lennon, Vanda A.
author_sort	Apiwattanakul, Metha
title	Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy
title_short	Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy
title_full	Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy
title_fullStr	Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy
title_full_unstemmed	Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy
title_sort	signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy
description	Introduction: Paraneoplastic autoantibody screening of 150,000 patient sera by tissue‐based immunofluorescence incidentally revealed 170 with unsuspected signal recognition particle (SRP) immunoglobulin G (IgG), which is a recognized biomarker of autoimmune myopathy. Of the 77 patients with available information, 54 had myopathy. We describe the clinical/laboratory associations. Methods: Distinctive cytoplasm‐binding IgG (mouse tissue substrate) prompted western blot, enzyme‐linked immunoassay, and immunoprecipitation analyses. Available histories were reviewed. Results: The immunostaining pattern resembled rough endoplasmic reticulum, and mimicked Purkinje‐cell cytoplasmic antibody type 1 IgG/anti‐Yo. Immunoblotting revealed ribonucleoprotein reactivity. Recombinant antigens confirmed the following: SRP54 IgG specificity alone (17); SRP72 IgG specificity alone (3); both (32); or neither (2). Coexisting neural autoantibodies were identified in 28% (low titer). Electromyography revealed myopathy with fibrillation potentials; 78% of biopsies had active necrotizing myopathy with minimal inflammation, and 17% had inflammatory myopathy. Immunotherapy responsiveness was typically slow and incomplete, and relapses were frequent on withdrawal. Histologically confirmed cancers (17%) were primarily breast and hematologic, with some others. Conclusions: Autoimmune necrotizing SRP myopathy, both idiopathic and paraneoplastic, is underdiagnosed in neurological practice. Serological screening aids early diagnosis. Cancer surveillance and appropriate immunosuppressant therapy may improve outcome. Muscle Nerve 53: 925–932, 2016
publisher	John Wiley and Sons Inc.
publishDate	2016
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5067628/
_version_	1613687232062816256

Signal recognition particle immunoglobulin g detected incidentally associates with autoimmune myopathy

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