PL9-11 derived autoantibodies catalyze dsDNA antigen in an isotype dependent manner. Different isotypes of the PL9-11 parent anti-DNA antibody were mixed with linear dsDNA (500 bp) before incubation at 4°C overnight. dsDNA fragments were visualized by gel analysis. (a) IgG3, IgG2a, and IgG2b PL9-11, but not the respective isotype controls, cleaved dsDNA. Increasing molar ratios promoted the cleavage. (b) Higher molar ratio (25:1) of IgG3 and IgG2b to dsDNA caused the disappearance of dsDNA, while the isotype controls had little effect. Data were from three to five independent experiments. Representative images are shown.