Anti-DNA antibody mediated catalysis is isotype dependent

Abstract

Anti-DNA antibodies are the serological hallmark of systemic lupus erythematosus, and participate in the pathogenesis of lupus nephritis by cross-reacting with multiple renal antigens. Previously, using a panel of murine anti-DNA IgGs that share identical variable regions but that differ in the constant regions, we demonstrated that the cross-reaction and renal pathogenicity of anti-DNA antibodies are isotype dependent. In this study, we investigated the catalytic potential of this anti-DNA antibody panel, and determined its isotype dependency. The three isotype switch variants (IgG1, IgG2a, IgG2b) and the parent IgG3 PL9-11 anti-DNA antibodies were compared in their catalysis of 500 base pair linear double stranded DNA and a 12-mer peptide (ALWPPNLHAWVP), by gel analysis, MALDI-TOF mass spectrometry, and nuclear magnetic resonance spectroscopy. The binding affinity of anti-DNA antibodies to double stranded DNA and peptide antigens were assessed by ELISA and surface plasmon resonance. We found that the PL9-11 antibody isotypes vary significantly in their potential to catalyze the cleavage of both linear and double stranded DNA and the proteolysis of peptides. The degree of the cleavage and proteolysis increases with the incubation temperature and time. While different PL9-11 isotypes have the same initial attack sites within the ALWPPNLHAWVP peptide, there was no correlation between binding affinity to the peptide and proteolysis rates. In conclusion, the catalytic properties of anti-DNA antibodies are isotype dependent. This finding provides further evidence that antibodies that share the same variable region, but which have different constant regions, are functionally distinct. The catalytic effects modulated by antibody constant regions need to be considered in the design of therapeutic antibodies (abzymes) and peptides designed to block pathogenic autoantibodies.

A Monoclonal Antibody to Cryptococcus neoformans Glucuronoxylomannan Manifests Hydrolytic Activity for Both Peptides and Polysaccharides

“…It is unclear why the V L would be more likely to contain catalytic activity than the V H , but it is possible that antibodies with catalytic H chains have simply been infrequently identified and are thus under-represented in the literature and the PDB. We also note that the C H is known to have significant effects on the catalytic activities of at least two different antibodies (28,29,50). Thus, if the hydrolytic active site is present in the V L , this would imply that major inter-domain and inter-chain conformational changes can be propagated in immunoglobulins, a topic that warrants further investigation (61,62).…”

Anti-Double-Stranded DNA IgG Participates in Renal Fibrosis through Suppressing the Suppressor of Cytokine Signaling 1 Signals

“…As described previously (36), an ABI 4800 Analyzer (AB Science, Foster City, CA, USA) was used for such analysis. The ALW ( l -form or d -form) and KIR peptides (2 µg/ml) were mixed with anti-dsDNA IgG or control IgG (molar ratio = 1:5), respectively.…”

IgG cooperativity – Is there allostery? Implications for antibody functions and therapeutic antibody development

“…In an NMR study, the authors observed differences between the IgG subclasses with respect to their catalytic potential to cleave DNA, as well as the proteolytic activity toward a peptide mimic of the antigen. 137 While the 4 mAbs had the same primary cleavage sites for the peptide antigen, the catalytic efficiency differed among the subclasses. There was no correlation between the catalytic rates and the binding affinities to the peptide antigens.…”