Antibodies against pancreatic ribonuclease A hydrolyze RNA and DNA

The sera of patients with autoimmune (AI) diseases contain antibodies with DNase and RNase activities. We have shown for the first time that immunization of healthy rabbits with RNase A conjugated with BSA produces a better immune response than immunization with pure RNase and induced IgGs with RNase and DNase activities, which were intrinsic properties of IgGs, while polyclonal IgGs (pIgGs) from non-immunized rabbits and animals immunized with BSA were catalytically inactive. It was shown that 74-85% of the total IgG DNase and RNase activities belongs to anti-idiotypic antibodies to RNase A (0.6-0.8% of total pIgGs), while 15-26% of the activities cannot interact with Sepharose-bearing antibodies against RNase A and may be antibodies to nucleic acids bound to RNase. Affinity chromatography on DNA-cellulose separated catalytic IgGs into several antibody subfractions demonstrating only DNase or RNase activity or hydrolyzing RNA faster than DNA. Our data suggest that a fraction of abzymes (or catalytically active antibodies) from AI patients hydrolyzing both DNA and RNA may be antibodies against RNase or its complexes with other proteins.