M Infantino1, M Manfredi2, V Grossi2, M Benucci3, G Morozzi4, E Tonutti5, M Tampoia6, N Bizzaro7. 1. SOS Laboratorio Immunologia e Allergologia, Ospedale S. Giovanni di Dio, Firenze, Italy. Electronic address: maria2.infantino@uslcentro.toscana.it. 2. SOS Laboratorio Immunologia e Allergologia, Ospedale S. Giovanni di Dio, Firenze, Italy. 3. SOS Reumatologia, Ospedale S. Giovanni di Dio, Firenze, Italy. 4. Dip. Scienze Mediche, Chirurgiche e Neuroscienze, Università di Siena, Siena, Italy. 5. Immunopatologia e Allergologia, Azienda Ospedaliero-Universitaria, Udine, Italy. 6. Laboratorio di Patologia Clinica, Azienda Ospedaliera Universitaria, Policlinico di Bari, Bari, Italy. 7. Laboratorio di Patologia Clinica, Ospedale San Antonio, Tolmezzo, Italy.
Abstract
BACKGROUND: Patients with suspected idiopathic inflammatory myopathies (IIM) are commonly tested for the presence of anti-nuclear antibodies (ANA) by indirect immunofluorescence (IIF) on HEp-2 cell substrates. However, ANA-IIF false negative tests may occur in IIM because some antigens, such as Jo1 and Ro52, may be scarcely expressed on HEp-2 cells. In addition, cytoplasmic staining is often not appropriately investigated by a specific antibody assay, leading to decreased clinical sensitivity of the ANA test. We evaluated the diagnostic impact of different strategies using different combination of myositis-related autoantibody tests. METHODS: Sera from 51 patients with an established diagnosis of IIM were tested for ANA by IIF on HEp-2 cells and for myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) by lineblot methods. RESULTS: Forty-four/51 (86.3%) samples tested positive with at least one of the three methods and seven were negative with all methods. Of the 44 positive samples, 9 (20.5%) tested negative for the ANA-IIF test and positive for MAA/MSA. Anti-Ro52 were the most prevalent autoantibodies in IIM patients (21/51; 41%), frequently associated with anti-Jo1 antibodies (13/21; 62%). 13 (16%) anti-Ro52 and anti-Jo1 negative samples were reactive to MSA. CONCLUSIONS: Our findings suggest that when IIM is clinically suspected, the optimal diagnostic algorithm is to associate the ANA-IIF screening test with a specific test for anti-Ro52 and anti-Jo1 antibodies. Should all these tests be negative, serological tests for MSA are recommended.
BACKGROUND:Patients with suspected idiopathic inflammatory myopathies (IIM) are commonly tested for the presence of anti-nuclear antibodies (ANA) by indirect immunofluorescence (IIF) on HEp-2 cell substrates. However, ANA-IIF false negative tests may occur in IIM because some antigens, such as Jo1 and Ro52, may be scarcely expressed on HEp-2 cells. In addition, cytoplasmic staining is often not appropriately investigated by a specific antibody assay, leading to decreased clinical sensitivity of the ANA test. We evaluated the diagnostic impact of different strategies using different combination of myositis-related autoantibody tests. METHODS: Sera from 51 patients with an established diagnosis of IIM were tested for ANA by IIF on HEp-2 cells and for myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) by lineblot methods. RESULTS: Forty-four/51 (86.3%) samples tested positive with at least one of the three methods and seven were negative with all methods. Of the 44 positive samples, 9 (20.5%) tested negative for the ANA-IIF test and positive for MAA/MSA. Anti-Ro52 were the most prevalent autoantibodies in IIM patients (21/51; 41%), frequently associated with anti-Jo1 antibodies (13/21; 62%). 13 (16%) anti-Ro52 and anti-Jo1 negative samples were reactive to MSA. CONCLUSIONS: Our findings suggest that when IIM is clinically suspected, the optimal diagnostic algorithm is to associate the ANA-IIF screening test with a specific test for anti-Ro52 and anti-Jo1 antibodies. Should all these tests be negative, serological tests for MSA are recommended.
Authors: Athanasios Gkoutzourelas; Christos Liaskos; Maria G Mytilinaiou; Theodora Simopoulou; Christina Katsiari; Alexandra Tsirogianni; Dimitrios Daoussis; Thomas Scheper; Wolfgang Meyer; Dimitrios P Bogdanos; Lazaros I Sakkas Journal: Front Immunol Date: 2018-12-07 Impact factor: 7.561