Comparison of Different Laboratory Methods in the Detection of Anti-dsDNA Antibodies and Their Diagnostic Utility

Introduction: We aimed to analyze the positivity of Crithidia luciliae immunofluorescence tests (CLIFT), to compare CLIFT with ANA-IFA (antinuclear antibody–immunofluorescence assay), ANA-IB (immunoblot), and ELISA (enzyme-linked immunoassays), and to determine the relevant method to test anti-dsDNA in systemic lupus erythematosus (SLE). Materials and Methods: We conducted a retrospective, cross-sectional study between January 1st, 2015 and January 1st, 2016. We focused on the positive CLIFT results firstly, then, we compared the ANA-IFA, ELISA, and ANA-IB results to diagnose SLE. Demographic features were obtained from the hospital records. Results: To analyse CLIFT, 3242 seras were tested, and 72 (2.2%) were positive. Among CLIFT positivity [n=64; 57 female, 7 male (mean, range; 41.96, 11–82)]; 73% (n=47) had SLE. Out of 61 patients were analyzed by ANA-IFA, 36 had peripheral (n=1) and homogenous (n=35) patterns; 83% (n=30) had SLE. Out of 46 patients were analyzed by ANA-IB, 30 had dsDNA; 73% (n=22) had SLE. Out of 25 patients who were analyzed by ELISA, 18 had dsDNA; 83% (n=15) had SLE. In the two-sided correlations, CLIFT positivity (≥grade 2) was found to be statistically significantly associated with having SLE (p=0.005, r [64]=0.92); CLIFT positivity was also statistically significantly associated with ANA-IFA (p=0.003, r=0.85). In order to exclude SLE diagnosis, CLIFT positivity was statistically significantly correlated with ANA-IB (p=0.002, r=0.90). Conclusion: CLIFT can not be used instead of ELISA and ANA-IB, but it can reduce their usage. We recommend to use CLIFT and ANA-IFA for first-line screening; and ANA-IB and ELISA for confirmation and identification of dsDNA.