[Kinetoplast of the flagellate crithidia luciliae: a suitable substrate for the detection of antibodies to native, double-stranded DNA in the indirect immuno-fluorescence test (author's transl)].

Sera from 29 patients with systemic lupus erythematosus (SLE), 60 cases of rheumatoid arthritis, 34 of myasthenia gravis (MG), 10 of scleroderma and 20 control sera were investigated for the occurrence of antibodies to native, double-stranded (ds) deoxyribonucleic acid (DNA). An immunofluorescence procedure recently elaborated by Aarden and coworkers, which utilizes the kinetoplast of the hemoflagellate Crithidia luciliae as substrate, was employed. In this kinetoplast, native, ds-DNA is concentrated as a single large network. Antibodies reacting with kinetoplasts were restricted to the SLE group, with the exception of one MG serum which also exhibited a distinct kinetoplast fluorescence. The antibody activity of the SLE sera could be completely inhibited by small amounts of DNA and abolished by deoxyribonuclease treatment of the substrate. These findings underline the specificity of the test system for anti-ds-DNA antibodies and the high disease-specificity of these antibodies for SLE. With respect to its ease and speed of performance this highly reliable and specific flagellate test surpasses other known tests for the detection of anti-ds-DNA antibodies.