Dense fine-speckled 70 (DFS70) antibody – an antinuclear antibody (ANA) pattern that can be detected in indirect immunofluorescence (IIF), is a potential marker for the exclusion of systemic autoimmune rheumatic diseases (SARD), in the absence of other SARD-associated autoantibodies.

A new study published in Clinical Rheumatology investigated the frequency of anti-DFS70 antibodies in patients with SARD and in the blood bank donors (BD).

The study enrolled 418 rheumatoid arthritis (RA), 101 systemic lupus erythematosus (SLE), 71 Sjogrens syndrome (SS), 43 ankylosing spondylitis (AS), 36 systemic sclerosis-scleroderma (SSc)and2555 undifferentiated connective tissue disease (UCTD) patients, as well as 507 BD. Patient samples were tested on the HEp-2 IIF-ANA assay. Samples that showed DFS70 pattern in IIF were confirmed by a specific DFS70 antibody enzyme-linked immunosorbent assay (ELISA).

The results revealed DFS70 pattern in 1.33% among SARD patientsand 0.78% among BD. The anti-DFS70 antibody was detected in 0.59% among BD; 1.43% in RA; 2.97% in SLE; 1.40% in SS; and 0.97% in UCTD, but it was not detected in AS and SSc by ELISA. Moreover, there was no significant difference between BD and SARD. The frequency of anti-DFS70 was significantly different for SLE in SARD.

The findings suggested that anti-DFS70 antibody was more prevalent in the subsets of SARD than BD. This study highlighted the importance of anti-DFS70 antibodies as a diagnostic tool in systemic autoimmune rheumatic diseases and emphasized the need to verify the DFS70 pattern detected in IIF-ANA test for definitive diagnosis with additional confirmation methods.