Abstract
The antinuclear antibody (ANA) test is clinically important for the diagnosis of autoimmune diseases such as connective tissue diseases and autoimmune hepatitis. The aim of this study was to evaluate the clinical utility of a screening test for eight disease-specific ANAs using a chemiluminescence enzyme immunoassay (CLEIA-ANA) in routine ANA tests and comparing the results with those of an indirect immunofluorescence assay (IF-ANA). In this study, we analyzed patients with rheumatic, dermatological, and gastrointestinal diseases because ANA tests are clinically important for these disorders. The concordance rate between CLEIA-ANA and IF-ANA (1:40) was low (41.9%) in patients with gastrointestinal diseases, suggesting that autoantibodies detected by IF-ANA alone were clinically important. The concordance rates between CLEIA-ANA and IF-ANA (1:160) were 72.8% in patients with rheumatic diseases and 77.5% in patients with dermatological diseases. CLEIA-ANA efficiently detects eight disease-specific ANAs including anti-SS-A antibody, which is frequently overlooked in patients with rheumatic and dermatological diseases when using IF-ANA. The positivity rate for a dense fine speckled (DFS) staining pattern in sera from CLEIA-ANA-negative/IF-ANA-positive patients (1:160) was significantly higher in patients with dermatological diseases (17/45) than in those with rheumatic diseases (5/40) (p = 0.0123). Of 17 patients with dermatological diseases with a DFS staining pattern, 16 were positive for the anti-DFS70 antibody, which is frequently detected in those with skin diseases and in healthy subjects. Indeed, more than half of the 16 patients had a skin disease. In summary, CLEIA-ANA efficiently detects eight disease-specific ANAs in routine ANA tests of patients with rheumatic and dermatological diseases, although in some other patients, such as those with gastrointestinal diseases, they are undetectable by CLEIA-ANA owing to solid-phase antigens.
