Comparison of antinuclear antibody profiles obtained using line immunoassay and fluorescence enzyme immunoassay

Objective: LIA-ANA-Profile-17S is a multiplex line immunoassay that simultaneously detects 17 antinuclear antibodies (ANAs) against extractable nuclear antigens (ENAs). We evaluated the utility of LIA-ANA-Profile-17S as a supplement to ANA indirect immunofluorescence (IIF) and EliA ENA (a fluorescence enzyme immunoassay) for diagnosis of ANA-associated rheumatic diseases. Methods: Sera were collected from 245 patients referred for an ANA IIF test. LIA-ANA-Profile-17S results were compared with those of EliA ENA. The kappa coefficients, agreement rates, and diagnostic performance of these tests were assessed for systemic lupus erythematosus (SLE) and Sjögren’s syndrome (SjS). Results: We observed almost perfect interassay agreement for antibodies against Ro52/Ro60, CENP-B, and Scl-70 (kappa = 0.91, 0.97, and 1.00, respectively); strong agreement for anti-SS-B/La antibody (kappa = 0.81); and relatively low agreement for other antibodies, including those against dsDNA, Sm, RNP, and Jo-1. For SLE diagnosis, LIA-ANA-Profile-17S showed lower sensitivity and similar specificity compared with EliA ENA. The sensitivity and specificity of these two assays were similar for SjS diagnosis. Conclusions: The specificity of LIA-ANA-Profile-17S was enhanced when combined with ANA IIF and was comparable with that of EliA ENA. LIA-ANA-Profile-17S showed relatively good agreement with EliA ENA. In combination with ANA IIF, these assays showed enhanced diagnostic performance.