Anti-DNA antibodies bind to DNase I.

Abstract

SummaryPolyspecificity is a well-known property of the anti-DNA antibodies produced by autoimmune animals. In our search for antigen targets of anti-DNA antibodies within tissue extracts, we identified a 32-kD polypeptide that was recognized by a large panel of anti-DNA antibodies. Direct sequencing of this protein disclosed its identity with DNase I. 22 monoclonal anti-DNA antibodies bound to DNase I in direct and competitive immunoassays; out of 15 autoantibodies that did not bind DNA, none had the ability to bind DNase I. The ability of anti-DNA antibodies to interfere with DNase I enzymatic activity was evaluated in an assay based on the enzyme digestion of phage double strand DNA. Six monoclonal anti-single strand DNA antibodies that did not bind double strand DNA were tested in this assay. Three out of six inhibited DNase I-mediated digestion of phage DNA. The interaction of anti-DNA antibodies with DNase I was further investigated by testing their ability to bind a synthetic peptide that corresponds to the catalytic site of the molecule. 4 out of 22 anti-DNA antibodies bound the active site peptide; two of these had been shown to inhibit DNase I enzymatic activity. This report shows that anti-DNA antibodies recognize both DNA and its natural ligand DNase I. Some anti-DNA antibodies inhibit DNase I enzymatic activity, thus displaying the potential to modulate DNA catabolism. The dual specificity of anti-DNA antibodies offers a clue for understanding the mechanisms that lead to anti-DNA antibody production in autoimmune animals.

Measurement of deoxyribonuclease I (DNase) in the serum and urine of systemic lupus erythematosus (SLE)-prone NZB/NZW mice by a new radial enzyme diffusion assay

“…Rat DNase I carries two mutations (E 13 to D and V 67 to I) responsible for the decrease in actin-binding of rat DNase I [3]. Contrary to the findings of Emlen et al [29] and Pucetti et al [30], we were unable to demonstrate any inhibitory or protective effect of anti-DNA antibodies on the reaction of DNase with DNA in agarose gels. Emlen et al [29] have shown that a 35-45 base pair (bp) DNA fragment in SLE sera is protected from DNase digestion and remains bound to antibody, thereby forming a small, DNase-resistant DNA-anti-DNA immune complex.…”

The treatment of systemic lupus erythematosus (SLE) in NZB/W F1 hybrid mice; studies with recombinant murine DNase and with dexamethasone

“…In any event, the formation of anti-DNase antibody in the treated group did not prevent them from doing better than the diluent-treated controls. The absence of any antiDNase antibody in control mice at times when they had high titres of anti-DNA antibody conflicts with the finding of Puccetti et al [35] that many anti-DNA antibodies bind to DNase. Their suggestion that DNase may be the antigen giving rise to anti-DNA certainly does not seem to be the case in NZB//W F 1 mice.…”

Neutrophil Extracellular Traps That Are Not Degraded in Systemic Lupus Erythematosus Activate Complement Exacerbating the Disease

“…Hence, the deposition probably did not generate high enough Ab concentrations for such inhibition. Alternatively, anti-DNA Abs have been described to cross-react with DNase-I, which could potentially explain inhibition by Abs in solution but not by deposited Abs (41).…”