IMMUNOFLUORESCENCE ASSAY FOR DOUBLE-STRANDED DNA ANTIBODIES USING CRITHIDIA-LUCILIAE KINETOPLAST AS A DOUBLE-STRANDED DNA SUBSTRATE

Abstract

Circulating antibodies to ds[double stranded]DNA are found predominately in SLE [systemic lupus erythematosus] and are seen most often in those patients with active systemic disease, particularly severe lupus glomerulonephritis. An IFF [indirect immunofluorescence] technique for measuring these antibodies was recently described. This uncomplicated assay employs the kinetoplast of the nonpathogenic hemoflagellate C. luciliae as a dsDNA substrate. Although slightly less sensitive than a radioimmunoassay, this IF technique was shown in this report to be a specific and reliable qualitative method for detecting anti-dsDNA. An estimate of the amount of DNA antibody present can be obtained by serum titration. The test was positive in only two patient groups tested, SLE (48%) and MCTD (20%) [mixed connective tissue disease].