Antibodies against double-stranded DNA in patients with connective tissue diseases. Comparison between Crithidia luciliae kinetoplast immunofluorescence test and Farr technique.

Antibodies against double-stranded (ds) DNA were demonstrated by an immunofluorescence technique using Crithidia luciliae kinetoplast as antigen, and by means of the Farr technique. Both techniques were used simultaneously in 172 sera from patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), juvenile rheumatoid arthritis (JRA), temporal arteritis (TA) and from healthy controls. Comparable results were obtained with the two techniques. SLE patients with active disease had higher titres of IgA antibodies than patients with inactive disease. Of the patients with RA and JRA, 10% had significant titres of dsDNA antibodies. Patients with TA and normal controls had either no dsDNA antibodies in their sera or very low titres without complement-fixing properties.