False-positive myeloperoxidase binding activity due to DNA/anti-DNA antibody complexes: A source for analytical error in serologic evaluation of anti-neutrophil cytoplasmic autoantibodies

H. S. Jethwa, P. H. Nachman, R. J. Falk, J. C. Jennette

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Anti-myeloperoxidase antibodies (anti-MPO) are a major type of anti-neutrophil cytoplasmic antibody (ANCA). While evaluating anti-MPO monoclonal antibodies from SCG/Kj mice, we observed several hybridomas that appeared to react with both MPO and DNA. Sera from some patients with systemic lupus erythematosus (SLE) also react with MPO and DNA. We hypothesized that the MPO binding activity is a false-positive result due to the binding of DNA, contained within the antigen binding site of anti-DNA antibodies, to the cationic MPO. Antibodies from tissue culture supernatants from 'dual reactive' hybridomas were purified under high-salt conditions (3 M NaCl) to remove any antigen bound to antibody. The MPO and DNA binding activity were measured by ELISA. The MPO binding activity was completely abrogated while the DNA binding activity remained. The MPO binding activity was restored, in a dose-dependent manner, by the addition of increasing amount of calf-thymus DNA (CT-DNA) to the purified antibody. Sera from six patients with SLE that reacted with both MPO and DNA were treated with DNase and showed a decrease in MPO binding activity compared with untreated samples. MPO binding activity was observed when CT-DNA was added to sera from SLE patients that initially reacted with DNA but not with MPO. These results suggest that the DNA contained within the antigen binding site of anti-DNA antibodies could bind to the highly cationic MPO used as substrate antigen in immunoassays, resulting in a false-positive test.

Original languageEnglish (US)
Pages (from-to)544-550
Number of pages7
JournalClinical and Experimental Immunology
Volume121
Issue number3
DOIs
StatePublished - 2000
Externally publishedYes

Keywords

  • ANCA
  • Anti-DNA
  • Anti-MPO
  • Systemic lupus erythematosus

Fingerprint Dive into the research topics of 'False-positive myeloperoxidase binding activity due to DNA/anti-DNA antibody complexes: A source for analytical error in serologic evaluation of anti-neutrophil cytoplasmic autoantibodies'. Together they form a unique fingerprint.

Cite this