A double antibody solid phase assay for DNA autoantibodies for clinical use

Area of Science:

• Immunology
• Clinical Chemistry
• Rheumatology

Background:

• Autoantibodies to DNA are key biomarkers in autoimmune diseases.
• Existing detection methods can be affected by various interfering factors.
• Accurate quantification and classification of DNA autoantibodies are crucial for diagnosis.

Purpose of the Study:

• To develop and validate a quantitative method for detecting DNA autoantibodies in serum.
• To assess the utility of the assay in distinguishing between systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).
• To compare the new assay's performance with established methods like the Farr test and antinuclear antibody (ANA) titres.

Main Methods:

• Serum samples were analyzed for DNA autoantibodies using antigen-coated polystyrene tubes.
• Detection involved radiolabelled anti-immunoglobulin.
• The assay was tested with both double-stranded and single-stranded DNA antigens.
• Results were compared with Farr test and ANA titres.

Main Results:

• The developed method provides quantitative data and antibody class information.
• It demonstrates good discrimination between SLE and RA using double-stranded DNA.
• Single-stranded DNA preparations showed elevated antibodies in approximately 40% of RA patients.
• A portion of SLE sera exhibited high background binding to gelatine-coated tubes.

Conclusions:

• The new radioimmunoassay offers a robust and quantitative approach for DNA autoantibody detection.
• It shows potential as a diagnostic tool for differentiating SLE from RA.
• Further investigation into the high background binding observed in some SLE samples is warranted.