Antibodies against polyriboadenylic acid in systemic lupus erythematosus and rheumatoid arthritis demonstrated by ELISA. Prevalence of and relation to antibodies against DNA and extractable nuclear antigens.

An enzyme-linked immunosorbent assay (ELISA) for the demonstration of class-specific antibodies against polyriboadenylic acid (poly-(A)) is described. The results revealed the presence of IgG-anti-poly(A) antibodies in 63% (22/35) of patients with systemic lupus erythematosus (SLE) and in 25% (22/88) of patients with rheumatoid arthritis (RA), the mean antibody level being significantly higher in the SLE patients. Anti-poly(A) antibodies of IgM class were seen in 15 and 17% of the patients, respectively. The prevalence of anti-poly(A) and anti-ssDNA antibodies of IgG class was similar in the patients with SLE, but the occurrence of antibodies against poly(A), DNA and extractable nuclear antigens varied independently of each other. In the RA-patients, a positive correlation was seen between the levels of IgG-anti-ssDNA and IgG-anti-poly(A) antibodies.