Determination of specific autoantibodies in patients with systemic lupus erythematosus by Line immunoassay, ELISA and CLIF assay.

ABSTRACT

BACKGROUND: Detection of specific antinuclear-antibodies is very importance in term of diagnosis, prognosis and management of patients with systemic lupus erythematosus (SLE). To date, Line immunoassay (LIA), enzyme-linked immunosorbent assay (ELISA) and Crithidia luciliae indirect immunofluorescence (CLIF) assay are commonly used for detection of specific antinuclear-antibodies. OBJECTIVE: To determine the performance of LIA, ELISA and CLIF for the detection of anti-double-stranded DNA (dsDNA), anti-nucleosome, and anti-extractable nuclear antigens (ENA) antibodies in patients with SLE. METHODS: A total 100 sera from 50 patients with SLE, 25 patients with disease control and 25 healthy control subjects were tested for anti-dsDNA, anti-nucleosome, and anti-ENA antibodies by LIA, ELISA, and CLIF assay. Agreement and diagnostic performance of each assay were analyzed using Cohen's kappa coefficient and receiver operating characteristic curve analysis. RESULTS: For the detection of anti-dsDNA antibody, ELISA had a substantial agreement with CLIF assay (? = 0.74) but LIA had a fair agreement with ELISA and CLIF assay (? = 0.37, and 0.35 respectively). For the detection of anti-nucleosome, anti-nRNP/Sm, anti-Sm, anti-SSA, and anti-SSB antibodies, LIA had a substantial to perfect agreement with ELISA (? = 0.64, 0.78, 0.68, 0.91, and 0.74, respectively). Anti-dsDNA-NcX ELISA and anti-dsDNA CLIF assay had equally diagnostic performance (sensitivity, 66% vs. 68%, and specificity, 96% vs. 94%, respectively) whereas, anti-dsDNA LIA has low sensitivity (22%) but high specificity (100%). CONCLUSIONS: LIA, ELISA, and CLIF demonstrated comparable performance for the detection of specific antinuclear-antibodies. However, there were some discrepancy between assays particularly in the detection of anti-dsDNA antibody.