Double-stranded DNA antibodies: a comparison of four methods of detection.

Thirty-four antinuclear antibody (ANA) positive systemic lupus erythematosus (SLE) sera were tested for antibodies to double-stranded DNA (dsDNA) simultaneously using Farr, haemagglutination, Crithidia luciliae (CL) kinetoplast fluorescence and human metaphase chromosome fluorescence assays. Significant correlation (p less than 0 x 05) was found between the Farr and CL assays, with the two fluorescence tests (CL and metaphase) displaying the greatest degree of association (p = 0 x 00001). No correlation could be demonstrated between the haemagglutination test and any of the other three assays. Six hundred and ninety-one sera from patients with a range of provisional rheumatological diagnoses were prospectively analysed for dsDNA antibodies using Farr and metaphase assays. A correlation coefficient of 0 x 84 was obtained between the two assays. The metaphase assay provides comparable results to other more established assays, and because it is simple, reliable and sensitive, it should be seriously considered for routine use in testing for dsDNA antibodies.