Immunization of rabbits with DNase II leads to formation of polyclonal antibodies with DNase and RNase activities

Abstract

The serum of patients with many autoimmune (AI) diseases contains small fractions of antibodies possessing both DNase and RNase activities. It was shown that immunization of rabbits with DNA, RNA, DNase I and RNase leads to production of antibodies with DNase and RNase activities. It is not known whether anti-idiotypic antibodies against DNase II can possess DNase or RNase activity. Electrophoretically and immunologically homogeneous polyclonal IgGs (pIgGs) from the sera of rabbits immunized with DNase II were obtained by sequential chromatography of the serum proteins on Protein A-Sepharose and gel filtration. It was shown for the first time that immunization of healthy rabbits with bovine DNase II produces IgGs with intrinsic DNase and RNase activities. IgGs from rabbits immunized with BSA or non-immunized animals were catalytically inactive. It was shown that approximately 10% of the total IgG DNase and RNase activities belong to anti-idiotypic antibodies to DNase II ( approximately 0.1% of total pIgGs), while 90% of the activities did not interact with Sepharose bearing antibodies against DNase II and might be antibodies to nucleic acids bound to DNase II. Affinity chromatography on DNA-cellulose using elution of antibodies with different concentration of NaCl and an acidic buffer separated catalytic IgGs into five antibody subfractions, three of which hydrolyzed RNA faster than DNA while two subfractions demonstrated only DNase activity. Our data suggest that a fraction of abzymes from AI patients hydrolyzing both DNA and RNA can contain subfraction of antibodies against DNase II.