Comparisons between immunoprecipitation and line blot assays in 110 patients with inflammatory myopathies according EULAR/ACR criteria
| Antibody | LB n (%) | IP n (%) | Cohen’s kappa | Concordance on positive sera (%)* | Concordance on negative sera (%)* |
| Anti-Jo-1 | 18 (16) | 12 (11) | 0.7 | 11 (10) | 92 (83) |
| Anti-PL-12 | 1 (1) | 0 | 0.0 | NA | NA |
| Anti-PL-7 | 0 | 0 | NA | NA | NA |
| Anti-Ej | 0 | 0 | NA | NA | NA |
| Anti-OJ | 0 | 1 (1) | 0.0 | NA | NA |
| Anti-SRP | 3 (3) | 4 (4) | 0.85 | 3 (3) | 107 (96) |
| Anti-PmScl (75/100kD) | 3 (3) | 5 (5.0) | 0.48 | 2 (2) | 105 (95) |
| Anti-Ku | 4 (4) | 3 (3) | 0.85 | 3 (3) | 107 (96) |
| Anti-SAE | 4 (4) | 3 (3)† | 0.85 | 3 (3) | 107 (96) |
| Anti-NXP2 | 2 (2) | 0 | 0.0 | NA | NA |
| Anti-MDA5 | 1 (1) | 3 (3) | 0.49 | 1 (1) | 108 (97) |
| Anti-TIF1γ | 8 (7) | 12 (11) | 0.56 | 6 (5) | 97 (87) |
| Anti-Mi-2(α/β) | 8 (7) | 2 (2) | 0.38 | 2 (2) | 103 (93) |
*The percentage represent the proportion among the 110 patients.
†The IP assay showed 40/90kD bands in ¾ patients, suggesting a positivity for SAE1.
ACR, American College of Rheumatology; EULAR, European League Against Rheumatism; IP, immunoprecipitation; LB, line blot.