Antibodies binding polyriboadenylic acid in systemic lupus erythematosus. Immunochemical characterization and isolation by affinity chromatography.

Antibodies specific for polyriboadenylic acid (poly rA) are present in sera from patients with systemic lupus erythematosus and from NZB/NZW F1 mice. The specificity of these antibodies was established by inhibition of [3H]poly rA binding and by affinity chromatography. Poly rA binding was associated with the 19S and 7S regions when serum was fractionated by sucrose density gradient untracentrifugation. Young NZB/NZW F1 mice (1-5 months) had only 19S anti-poly rA, whereas old NZB/NZW F1 mice (2 years) had activity in both 19S and 7S regions, suggesting a possible age-dependent switching mechanism in the spontaneous development of antibodies to nucleic acids. The gamma-globulin fraction from an SLE patient was subjected to affinity chromatography on a column of poly rA covalently linked to Sepharose. An enriched population of IgG antibodies binding only poly rA, but not native or denatured DNA, was isolated in this manner. This procedure may have broad biological applicability for the preparation of isolated immunospecific anti-nucleic acid antibodies.