Department of Medical Technology, Microbiology and Immunology^*, and Pathology^†, College of Medicine, National Cheng Kung University, Tainan, Taiwan 70101

Antibodies binding to bovine DNase were investigated by employing the ELISA technique using sera with or without antinuclear antibodies. About 54% ANA positive sera and 76% of SLE patients sera were positive for anti-DNase antibodies while only 5% of ANA negative sera were positive for anti-DNase and anti-DNA antibodies in patients sera. Furthermore, the isotypes of anti-DNase antibodies were mainly IgG which suggest that they were produced by specific antigen driven. In addition, indirect fluorescent antibody (IFA) using affinity-purified anti-DNase antibodies demonstrated that anti-DNase antibodies bound to the nuclei of Hep-2 cells with a speckle pattern. The affinity-purified anti-DNase antibodies could be captured by DNA coated ELISA but did not bind to kinetoplast of Crithidia as shown by IFA stain. In presence of these anti-DNase antibodies, the enzymatic activity of DNase from either bovine, human or streptococcus were all inhibited as shown by assays based on the enzyme digestion of phase double strand DNA and radial enzyme diffusion. These results suggested that the inhibition of DNase function by anti-DNase antibodies may enhanced the induction of anti-DNA antibodies by interfering DNA degradation in suspected hosts.