Neutrophil nuclear patterns to distinguish between pathological and non-pathological autoantibodies detected on HEp-2 cells

Background: Antinuclear antibody (ANA) testing is used to diagnose systemic autoimmune rheumatic disease (SARD). Autoantibodies (Abs) associated with the homogeneous-like pattern on ANA HEp-2 cell nuclei can be classified as pathological (e.g., anti-dsDNA, anti-nucleosome, anti-histone, anti-Scl-70 Abs) or non-pathological (e.g., anti-DFS70 Abs). Methods: Anti-neutrophil cytoplasmic anti-antibody (ANCA) testing was used to classify individuals who presented with a homogeneous-like pattern on ANA testing. Enrolled subjects included (1) young individuals with a dense fine speckled pattern on ANA testing (young non-SARD group, n = 58) and patients with (2) systemic lupus erythematosus (SLE) with anti-dsDNA Abs (SLE group, n = 33), (3) rheumatoid arthritis (RA) with anti-nucleosome, anti-histone Abs, and others (RA group, n = 42), and (4) diffuse systemic sclerosis (SSc) with Scl-70 Abs (diffuse SSc group, n = 11). Results: Negative rates (95% confidence interval) of neutrophil nuclear patterns on ANCA testing were: 96.6% (88.1%-99.6%) of the young non-SARD group, 3.0% (0.1%-15.8%) of the SLE group, 4.8% (0.6%-16.2%) of the RA group, and 54.5% (23.4%-83.3%) of the diffuse SSc group. The negative rate of the non-SARD group was significantly higher than those of the SARD group (all P < 0.05). Conclusions: ANCA testing helps to identify individuals with non-pathological anti-DFS70 Abs who present with homogeneous-like patterns in HEp-2 cell nuclei on ANA testing.