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Cytoplasmic 5′‐nucleotidase autoantibodies in inclusion body myositis: Isotypes and diagnostic utility
Author(s) -
Greenberg Steven A.
Publication year - 2014
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.24199
Subject(s) - autoantibody , 5' nucleotidase , isotype , inclusion body myositis , immunology , myositis , antibody , medicine , polymyositis , pathology , monoclonal antibody , adenosine
ABSTRACT Introduction : Recent studies have identified circulating immunoglobulin (Ig) G autoantibodies against cytoplasmic 5′‐nucleotidase 1A (cN1A; NT5C1A) in patients with inclusion body myositis (IBM), whose detection provides for an IBM blood diagnostic test. Whether or not anti‐cN1A autoantibody isotypes other than IgG are present in IBM has not previously been reported. Methods : Plasma and serum samples from 205 patients (50 with and155 without IBM) were studied for the presence of IgM and IgA, in addition to IgG, anti‐cN1A autoantibodies using immunoblots and enzyme‐linked immunoassays (ELISAs). Results : IgM, IgA, and IgG anti‐cN1A autoantibodies were detected by ELISA with similar sensitivities (49–53%) and specificities (94–96%), but with differing patterns of autoantibody isotype presence. Combination assays of all 3 autoantibody levels improved diagnostic sensitivity to 76%. Conclusions : In addition to previously recognized IgG anti‐cN1A autoantibodies, IBM patients have circulating IgM and IgA anti‐cN1A autoantibodies. Differing patterns of these isotypes may be present and useful for diagnosis. Muscle Nerve 50 : 488–492, 2014