Correspondence on ‘Standardisation of myositis-specific antibodies: where are we today?’

We have read with great interest the recent article from Espinosa-Ortega et al 1 and the commenting letter by Mahler et al 2 on the reliability of line immunoassay (LIA) versus immunoprecipitation (IP) in the detection of myositis-specific autoantibodies (MSAs) for the diagnosis of idiopathic inflammatory myopathies (IIM). Even if the search for MSA by dot immunoassay (DIA) or LIA has been used for over a decade and represents a ‘non-criteria’ test to assist clinicians in IIM diagnosis, MSAs have been included in classification criteria only for a couple of years.3 However, initial studies on the clinical utility of the DIA/LIA methods in diagnosing IIM were conducted on a restricted panel of MSA and mainly on selected IIM patients.4 …