[Evaluation of 2 methods for detecting anti-DNA antibodies in collagen disease]

An immunofluorescent technique using Crithidia luciliae (CL) has been developed to detect antibodies against native DNA, type them and determine their complement-fixing capacity. CL possess a kinetoplast containing double-stranded DNA that is not bound to histones: they are therefore a substrate well suited to the determination of antibodies against native DNA. When compared with a radioimmunoassay the technique displayed the same specificity and sensitivity. However, the correlation between clinical symptoms of SLE and anti-DNA antibody titer was better with the CL method than with radioimmunoassay. Determination of complement-fixing capacity and the type of immunoglobulins did not provide useful information. The CL method proved to be reliable, rapid and cheap.