Circulating DNA-antibodies in systemic lupus erythematosus

Area of Science:

• Immunology
• Rheumatology
• Molecular Biology

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by diverse clinical manifestations.
• Antibodies to DNA are key serological markers in SLE, but their specific roles in disease activity require further elucidation.
• Assessing different DNA antibody classes and subclasses is crucial for understanding SLE pathogenesis and monitoring disease progression.

Purpose of the Study:

• To evaluate the diagnostic and prognostic utility of different DNA antibody assays in patients with SLE.
• To correlate the levels of anti-double-stranded DNA (anti-ds-DNA) and anti-single-stranded DNA (anti-ss-DNA) antibodies with SLE disease activity.
• To investigate the association of anti-ds-DNA and anti-ss-DNA antibodies of IgG and IgM classes with specific clinical manifestations, particularly nephritis.

Main Methods:

• Sera from 57 SLE patients were analyzed using three distinct methods: Farr assay for anti-ds-DNA, Crithidia luciliae immunofluorescence assay for anti-ds-DNA, and a solid-phase immunoenzymatic assay for IgG and IgM anti-ss-DNA.
• Disease activity was assessed, and correlations between antibody levels and clinical parameters, including nephritis and disease activity scores, were statistically analyzed.
• Specific attention was paid to comparing antibody levels in patients with active versus inactive nephritis and those with or without nephritis.

Main Results:

• A positive correlation was observed between disease activity and levels of anti-ds-DNA antibodies and IgG anti-ss-DNA antibodies.
• Patients with active nephritis exhibited significantly higher levels of anti-ds-DNA and IgG anti-ss-DNA compared to those with inactive nephritis (P < 0.05 and P < 0.01, respectively).
• Lower levels of IgM anti-ss-DNA antibodies were found in SLE patients with nephritis compared to those without (P < 0.02), and a positive correlation existed between the IgG-anti-ss-DNA/IgM-anti-ss-DNA ratio and disease activity score.

Conclusions:

• The anti-ss-DNA assay, particularly the IgG class, shows potential utility in monitoring SLE disease activity and progression.
• Complement-fixing anti-ds-DNA and high Farr assay anti-ds-DNA levels are typically associated with active disease, especially nephritis and joint involvement.
• These findings underscore the importance of evaluating different DNA antibody specificities and subclasses for comprehensive SLE management.