[The diagnostic value of anti-DNA antibodies depends on the technic used for their detection].

Three anti-native DNA antibody detecting assays were compared using sera from 948 patients with clinical symptoms of connective tissue disease and 55 definite systemic lupus erythematosus patients. The Farr assay was more effective than the two other assays in the diagnosis of lupus. Anti-DNA antibody detection by ELISA was as sensitive as the Farr assay; in contrast indirect immunofluorescence on Crithidia luciliae had a significantly lower sensitivity, detecting less than one out of two cases of lupus detected. Particularly ELISA but also indirect immunofluorescence may give positive results in the absence of lupus, so that results obtained by each of these assays must be confirmed by the Farr assay if they are used in the diagnosis of lupus. The significance of antibodies detected by one assay but not by the others is discussed.