Crithidium luciliae immunofluorescence test (CL test) a simple and reliable method for detecting anti-native DNA antibodies.

Antibodies directed against native DNA using Crithidium lucillae as an antigen substrate were demonstrated in 39 of 72 cases of systemic lupus erythematosus (SLE) with active lesions whereas results were negative in 42 cases of SLE during remission and in 69 cases of other collagenoses, and in 20 healthy subjects. A clearcut correlation with the peripheral type of fluorescence of anti-nuclear antibodies (ANA) was found in the routine method of immunofluorescence on the monkey esophagus. Renal lesions were present in almost all cases of SLE with positive results of the test for Crithidium luciliae. The new technique of detecting antibodies against native DNA is simple and creates new diagnostic and prognostic possibilities in SLE.