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Anti-double stranded antibody. Association with titers and fluorescence patterns of anti-nuclear antibody in systemic lupus erythematosus.

OBJECTIVE
Many laboratories do not test antinuclear antibodies (ANA) by indirect immune-fluorescence (IIF) in parallel with anti-double stranded (ds) DNA antibodies. This study attempts to investigate the legitimacy of such practice.


METHODS
A retrospective laboratory data analysis of simultaneous assessment of ANA and anti-dsDNA antibody results of 106 patients with either diagnosed or suspected systemic lupus erythematosus (SLE) was performed at King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia. The ANA was detected by IIF on HEp2 cells and anti-dsDNA antibodies were assessed by specific ELISA test.


RESULTS
Among the patients, female preponderance (96.3%) was evident and a coarse speckled fluorescence pattern was commonly observed (60.4%). There was almost no detection of anti-dsDNA antibodies up to an ANA titer of 1:320. Anti-dsDNA antibodies were often detected at ANA titers of 1:640 and beyond. Other patterns of fluorescence observed at ANA titers as low as 1:40 and at higher dilutions were, fine speckled (14.15%), homogeneous (9.4%), anti-mitochondrial (7.5%), ribosomal (4.7%), and nucleolar (3.8%). Linear regression analysis revealed a statistically significant relationship (p=0.02) between ANA titers and anti-dsDNA antibodies only in the presence of a coarse speckled pattern.


CONCLUSION
The rare occurrence of anti-dsDNA antibodies at clinically significant ANA titers associated with the coarse speckled pattern may mask the diagnosis of SLE. Similarly, the diagnosis of SLE may be overlooked if anti-dsDNA antibodies are not checked in the presence of clinically insignificant ANA titers associated with other patterns of fluorescence.