Direct adsorption of ssDNA to polystyrene for characterization of the DNA/anti-DNA interaction, and immunoassay for anti-DNA autoantibody in New Zealand White mice.

DNA was adsorbed directly to polystyrene in concentrated NaCl (1.2 M) during simultaneous denaturation to single stranded form by high pH (12.0). Adsorption of single stranded DNA to polystyrene under these conditions (HsDNA) was complete within 15 min. DNA was not dissociated from polystyrene by NaCl concentrations as high as 5.0 M, nor by Tween 20 concentrations up to 50%. The method was ineffective for dT15 adsorption to polystyrene. HsDNA adsorption to polystyrene was compared to an indirect method in which methylated bovine serum albumin (mBSA) was adsorbed to polystyrene after which DNA was electrostatically bound to mBSA. DNA/mBSA interaction was affected by as low as 0.3 M NaCl. Using the DNA/mBSA assay, sera obtained from New Zealand White (NZW) mice showed IgG anti-DNA activity in approximately 50% of mice tested. HsDNA assay found greater than 62% of NZW mice have 10 micrograms anti-ssDNA or more per ml serum. Complex formation involving C1q complement and ssDNA in HsDNA assay were shown to be negligible. Anti-DNA autoantibody production by NZW implicated the NZW parental strain in autoimmunity of F1 progeny obtained from the New Zealand Black X NZW cross.