Antibodies to native and denatured DNA. Quantitation using an immuno-slot-blot technique

The attachment of DNA to nitrocellulose by suction filtration has been used as a prelude to DNA hybridization experiments, and several filter manifolds for this purpose are available. One suction manifold, the 'Minifold II slot-blotter', creates small, rectangular slots of bound DNA which can be probed using immunoenzymatic techniques and then evaluated with quantitative scanning densitometry. We applied this technique to the detection and quantitation of naturally occurring anti-DNA antibodies. After probing slot-blots of native or denatured DNA with human sera, the slot-blots were stained using an alkaline phosphatase second antibody system. The serum concentration of anti-DNA antibodies was determined by comparing the peak areas of the positive blots to a standard IgG curve. When native DNA was used as a substrate, these serum concentrations correlated well with the anti-DNA titer as measured by the Crithidia luciliae indirect immunofluorescence assay.