B-073 The Clinical Utility of Reporting AC-2 Pattern With Anti-DFS70 Antibody

Abstract Background The dense fine speckled (DFS) pattern (AC-2) is often observed in antinuclear antibody (ANA) indirect immunofluorescence (IIF) assay, and the related anti-DFS70 known to be negatively associated with a systemic autoimmune rheumatic disease (SARD). Identifying AC-2 challenging, as it could generally confused AC-1, AC-4, AC-5, or AC-29 patterns displaying stained metaphase plates nuclei. Since not included routine autoantibody tests, clinical utility of adequately applied laboratory practice. We evaluated prevalence other autoantibodies samples presenting ANA IIF assay. Additionally, we analyzed association antibodies features patients patterns. Method retrospectively reviewed images 1839 made by an automated analyzer classified AC-2, comprised 60.5% all positives (1839/3039). Among them, was identified 18.5% (341/1839) two experts, only 197 residual were available for further evaluation. Those tested enzyme-linked immunosorbent assay (ELISA) line immunoblot (LIA). They also 22 (dsDNA, nucleosomes, histones, SS-A/Ro-52, SS-B, RNP/Sm, Sm, Mi-2α, Mi-2β, Ku, CENP-A, CENP-B, Sp100, PML, Scl-70, PM/Scl100, PM/Scl75, RP11, RP155, gp210, PCNA) LIA. Clinical information from obtained retrospective review electronic medical records. Results Anti-DFS70 ELISA LIA 32.0% (63/197) 19.8% (39/197), respectively. agreement percentage between assays 81.7%, kappa value 0.53 (95% confidence interval: 0.40–0.66). Of 69 DFS70+ (as per LIA), coexistence found 81.2% (56/69). 128 DFS70- samples, 90.6% (116/128) revealed autoantibodies. three most frequent (except anti-DFS70) anti-SS-A/Ro-52 (30.5%, 60/197), anti-nucleosomes (27.4%, 54/197), anti-histones (20.3%, 40/197). There no significant difference DFS70− patients. SARD group 33.3% (50/150), non-SARD 40.4% (19/47) without difference. However, patients, isolated more frequently (36.8%, 7/19) than (12.0%, 6/50) (P = 0.0346). Conclusion positive rate lower third, affected different detection assays. Along pattern, just reporting presence valuable exclusion. Therefore, important co-examine autoantibodies, such anti-SS-A, anti-nucleosomes, anti-histones, confirm anti-DFS70.