Diagnostic performance of a commercial immunoblot assay for myositis antibody testing.
The objective of this study was to establish a population based reference range for a commercial immunoblot assay detecting myositis specific autoantibodies (MSAs) and myositis associated autoantibodies (MAAs), and to assess the diagnostic performance of this reference range against the manufacturer's recommended ranges in a myositis patient cohort. A total of 124 patients from a myositis cohort and 197 healthy controls were serologically assessed using a commercial immunoblot containing eleven autoantigens (Jo-1, EJ, OJ, PL7, PL12, Mi-2, SRP, Ku, PMScl75, PMScl100 and Ro52) according to the manufacturer's instructions. Use of the manufacturer's reference ranges resulted in detection of MSAs in 19.4% of myositis patients and 9.1% of controls; MAAs were detected in 41.1% of myositis patients and 14.2% of controls. Reference values derived from the healthy control population resulted in significant differences in cut-off values for some autoantibodies, particularly Ro52 and PMScl75. Use of local reference ranges reduced detection of MSAs to 16.9% of myositis patients and 3% of healthy controls, with MAAs 23.4% of patients and 2% of healthy controls. Application of population based reference ranges resulted in significant differences in detection of MSAs and MAAs compared to the manufacturer's recommended ranges. Cut-off levels should be assessed to ensure suitability for the population tested.
Department of Clinical Immunology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Perth, Australia; School of Pathology and Laboratory Medicine, and University of Western Australia, Perth, Australia.
Chris
C
Bundell
Western Australian Neuroscience Research Institute, University of Western Australia, Perth, WA, Australia; Department of Medicine, Yala Hospital, Yala, Thailand.
Arada
A
Rojana-Udomsart
Institute for Immunology and Infectious Diseases, Murdoch University, Perth, WA, Australia.
Frank
F
Mastaglia
Department of Clinical Immunology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Perth, Australia; School of Pathology and Laboratory Medicine, and University of Western Australia, Perth, Australia.
Peter
P
Hollingsworth
Department of Clinical Immunology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Perth, Australia. Electronic address: andymctooke@yahoo.co.uk.
Andrew
A
McLean-Tooke
D001323:Autoantibodies / Q000032:analysis*; D006801:Humans; D015151:Immunoblotting / Q000379:methods*; D009220:Myositis / Q000175:diagnosis* / Q000276:immunology
D001323:Autoantibodies
Autoantibodies; dermatomyositis; diagnosis; immunoblot; myositis; polymyositis