Anti-dsDNA: choice of assay in relation to clinical value

Abstract

Antibodies to DNA are quite specific for systemic lupus erythematosus (SLE) and occur in the majority of SLE patients. Therefore, their detection is an important diagnostic aid to the clinician. Detection of anti-dsDNA may precede the diagnosis of SLE by more than a year. Fluctuations in the level of anti-dsDNA in an individual patient may give important information on the clinical status of the patient. Four of the most important methods developed for the measurement of anti-dsDNA antibodies will be discussed in this paper: the Farr assay, the PEG assay, the indirect immunofluorescence test on Crithidia luciliae and the ELISA. They will also be compared with one commercially available (Farr) assay, the Amersham anti-dsDNA kit. Each method, detects a part of the spectrum of anti-dsDNA antibodies produced by a patient. The Farr assay is the most specific for SLE; however, milder forms of the disease in which patients have only low avidity anti-dsDNA may easily be missed by this technique. Clinically, high avidity anti-dsDNA is related more frequently to the occurrence of nephritis, whereas low avidity anti-dsDNA antibodies are found more often in patients with central nervous system involvement. Traditionally, SLE is considered an immune-complex disease, in which inflammatory processes are initiated by local deposition of DNA/anti-dsDNA complexes. More recently, a major role was thought to be played by crossreactions of anti-dsDNA with tissue constituents. Our current view, however, is that such a crossreactivity plays only a minor role; we postulate that binding to glomerular constituents is caused by anti-dsDNA antibodies complexed with DNA and histones.

Myth and reality: practical test system for the measurement of anti‐DNA antibodies in the diagnosis of systemic lupus erythematosus (SLE)

“…One study on 440 mixed SLE patients reported the sensitivity of the Farr assay at 95 and 99% SICC to be 72 and 56%, respectively (19), which is similar to our 76 and 57% and to the results from other previous studies (3). By combining the results for specimens identified as positive by the EL-ssDNA and EL-dsDNA at 99% SOCC with results from EL-dsDNA at the 95% SICC, three categories of specimens emerged: those very likely to have SLE (78%), likely to have SLE, but in need of confirmation by either Farr or CL-IFA (11%), and normal by any method (11%; Fig.…”

“…Second, the Farr radioimmunoassay is often the standard by which all other methods of anti-dsDNA antibodies detection in SLE are judged (2). Farr is quantitative, with results that can be expressed in IU/ml, measures high avidity antibodies, and is considered specific for SLE when high quality, radiolabeled, procariotic DNA is used (2)(3)(4). It has its drawbacks (5): cannot be automated and is the most labor intensive.…”

ROC Analysis Comparison of Three Assays for the Detection of Antibodies against Double-Stranded DNA in Serum for the Diagnosis of Systemic Lupus Erythematosus

“…Because ds-DNA-Ab may occur in a wide spectrum of diseases and even in healthy volunteers, diagnostic tests must be highly specific. The Farr RIA is assumed to meet this need best (4,5 ). To improve the diagnostic accuracy of ds-DNA-Ab tests, new tests have been developed, including ELISAs with different preparations of ds-DNA antigens as well as an automated enzyme fluoroimmunoassay using plasmid DNA as antigen.…”

“…Cytologic examination of peritoneal fluids forms part of the staging process for ovarian cancer and influences therapeutic interventions (3 ). It is known that regardless of International Federation of Gynecology and Obstetrics (FIGO) stage, positive peritoneal washing cytology predicts poor prognosis for women with epithelial tumors of the genital tract, except for patients with borderline ovarian tumors (4 ). Because of the diagnostic pitfalls entailed in the cytologic examination of peritoneal washings (5 ), some additional methods for peritoneal fluid diagnosis have been tested, including flow cytometric DNA analysis (6 ) and a telomerase assay (7,8 ).…”

Histone-containing Immune Complexes are to a Large Extent Responsible for Anti-dsDNA Reactivity in the Farr Assay of Active SLE Patients

“…Of these, the Farr assay is regarded as the most specific since it detects only antibodies with a relatively high avidity for dsDNA [14]. Recently, we demonstrated that Farr positivity can also be the result of binding of complexes composed of nucleosomal material and anti-nucleosome antibodies [15].…”