Abstract
AIM: To evaluate four different commercially available assays for anti-double stranded DNA (dsDNA) detection and compare them with the in-house radioimmunoassay according to Farr (FARR-RIA) in order to select the optimal primary method for use in combination with FARR-RIA. METHODS: Sera from 583 consecutive patients sent to our laboratory for routine diagnosis, 156 selected patients with autoimmune diseases (76 systemic lupus erythematosus [SLE] patients and 80 patients with other autoimmune diseases), and 150 blood donors were tested for anti-dsDNA antibodies with two enzyme-linked immunoassays (ELISA), two Crithidia luciliae immunofluorescence tests (CLIFT), and FARR-RIA. The specificities and sensitivities of the tests were calculated and compared. RESULTS: FARR-RIA and CLIFT 2 showed the highest specificity for SLE (100%), with CLIFT 2 showing higher sensitivity (33% vs 47%). Both ELISAs showed higher sensitivities (>53%) than FARR-RIA but lower specificities (<93%), whereas CLIFT 1 showed the lowest overall agreement with FARR-RIA. CONCLUSION: CLIFT 2 was selected as the primary test for use in combination with FARR-RIA. The use of CLIFT 2 reduced the number of sera that needed to be tested by FARR-RIA, the time needed to report the results, and environmental toxicity, cancerogenicity, and radioactivity.