Antibodies to dsDNA in connective tissue diseases measured by ultramicro enzyme-linked immunosorbent assay (ELISA) adapted to the chamber analytical technique (CAT).

Human sera (171 samples of patients with connective tissue diseases (CTD) were screened for anti-dsDNA antibodies by ultramicro ELISA adapted to the chamber analytical technique (CAT). The assay offers sensitivity superior to the Crithidia luciliae immunofluorescence technique (CLIFT). Positive results are not restricted to systemic lupus erythematosus (SLE). Nine sera of other CTD patients exhibited antibodies to dsDNA as well. This might be a symptom of a relatively slight immunodisturbance with presence of low-avidity antibodies.