Anti-double stranded DNA antibodies: A rational diagnostic approach in limited-resource settings.

Context: Anti-double-stranded deoxyribonucleic acid antibodies (dsDNA Abs) are highly specific markers of systemic lupus erythematosus (SLE). Multiple methods are employed for their detection in routine diagnostics.

Objectives: The aim of this study was to evaluate a diagnostic approach for anti-dsDNA Abs using DNA-ELISA and Crithidia luciliae fluorescence test (CLIFT), in combination with antinuclear antibody (ANA) screening.

Methods: We enrolled 113 patients-53 with SLE, 50 with other systemic autoimmune rheumatic diseases (OSARD), and 10 with non-autoimmune clinical conditions (NAICC).Patients' samples were tested for anti-dsDNA Abs using an enzyme-linked immunosorbent assay (ELISA) and CLIFT, combined to ANA screening by indirect immunofluorescence assay (ANA-IIFA).

Results: The mean age of patients was 39.94 ± 15 years (ranges: 11-85 years). Overall, specimens from 77.3%, 11.7%, and 20% of patients with SLE, OSARD and NAICC respectively were ELISA-positive; and those from 54.7% to 4% of patients with SLE and OSARD, respectively, were CLIFT-positive. CLIFT positivity was significantly associated with high ELISA titers (p = 0.002) and homogeneous ANA-IIF pattern (p = 0.0002).

Conclusion: For better clinical relevance of anti-dsDNA antibodies, we suggest a combined detection strategy based on ELISA, CLIFT and ANA-IIFA, considering the clinical criteria of SLE.