title: An analysis of the sensitivity and specificity of MHC-I and MHC-II immunohistochemical staining in muscle biopsies for the diagnosis of inflammatory myopathies.
abstract: Although there have been several previous reports of immunohistochemical staining for MHC antigens in muscle biopsies, there appears to be a lack of consensus about its routine use in the diagnostic evaluation of biopsies from patients with suspected inflammatory myopathy. Positive MHC-I staining is nonspecific but is widely used as a marker for inflammatory myopathy, whilst the role of MHC-II staining is not clearly defined. We investigated the sensitivity and specificity of MHC-I and MHC-II immunostaining for the diagnosis of inflammatory myopathy in a large group of biopsies from a single reference laboratory. Positive staining for MHC-I was found to have a high sensitivity in biopsies from patients with inflammatory myopathy but a very low specificity, as it was also common in other non-inflammatory myopathies and neurogenic disorders. On the other hand, MHC-II positivity had a much higher specificity in all major subgroups of inflammatory myopathy, especially inclusion body myositis. The findings indicate that the combination of MHC-I and MHC-II staining results in a higher degree of specificity for the diagnosis of inflammatory myopathy and that in biopsies with inflammation, positive MHC-II staining strongly supports the diagnosis of an immune-mediated myopathy. We recommend that immunohistochemical staining for both MHC-I and MHC-II should be included routinely in the diagnostic evaluation of muscle biopsies from patients with suspected inflammatory myopathy. However, as the sensitivity and interpretation of MHC staining may depend on the technique used, further studies are needed to compare procedures in different centres and develop standardised protocols.
authors.affiliation: Centre for Neuromuscular and Neurological Disorders, Western Australian Neuroscience Research Institute, Perth, Australia; Department of Neurology, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Rodríguez Cruz
authors.affiliation: Centre for Neuromuscular and Neurological Disorders, Western Australian Neuroscience Research Institute, Perth, Australia; Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Yue-Bei
authors.initials: YB
authors.lastname: Luo
authors.affiliation: Department of Neurology, Royal Victoria Infirmary, Newcastle-upon-Tyne, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Miller
authors.affiliation: Section of Neuropathology, Department of Anatomical Pathology, PathWest Laboratory Medicine WA, Royal Perth Hospital, Perth, Western Australia, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, Western Australia, Australia.
authors.forename: Reimar C
authors.initials: RC
authors.lastname: Junckerstorff
authors.affiliation: Centre for Neuromuscular and Neurological Disorders, Western Australian Neuroscience Research Institute, Perth, Australia; Institute for Immunology & Infectious Diseases, Murdoch University, Perth, Australia. Electronic address: f.mastaglia@iiid.com.au.
authors.forename: Frank L
authors.initials: FL
authors.lastname: Mastaglia
authors.affiliation: Section of Neuropathology, Department of Anatomical Pathology, PathWest Laboratory Medicine WA, Royal Perth Hospital, Perth, Western Australia, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, Western Australia, Australia.
authors.forename: Victoria
authors.initials: V
authors.lastname: Fabian
mesh_terms: D001706:Biopsy; D015395:Histocompatibility Antigens Class I / Q000032:analysis*; D000949:Histocompatibility Antigens Class II / Q000032:analysis*; D006801:Humans; D007124:Immunoenzyme Techniques; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D009135:Muscular Diseases / Q000175:diagnosis / Q000276:immunology / Q000473:pathology; D009220:Myositis / Q000175:diagnosis* / Q000473:pathology; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II
keywords: Inflammatory myopathies; MHC-I and MHC-II immunohistochemistry; Muscle biopsies; Non-inflammatory myopathies; Sensitivity; Specificity