DFS70 Autoantibodies: Clinical Utility in Antinuclear Antibody Testing

Screening for antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) on HEp-2 cells is helpful for the diagnosis and classification of ANA-associated rheumatic diseases, including systemic lupus erythematosus, Sjögren syndrome, mixed connective tissue disease, systemic sclerosis, and inflammatory myopathies. The dense fine speckled (DFS) pattern is a special HEp-2 IIF pattern (produced by anti-DFS70 antibodies) because it is not associated with a specific medical condition and therefore can obfuscate interpretation.

In this paper, detection methods for and clinical associations of anti-DFS70 antibodies are reviewed.

The target antigen of the antibodies that cause the DFS pattern is a 70 kDa protein (DFS70). Commercial methods that detect antibodies to full-length or truncated DFS70 are available for use in clinical laboratories (ELISA, chemiluminescence, dot/line blot). Anti-DFS70 can be found in (apparently) healthy individuals (with a higher frequency in young individuals and in females), in several (inflammatory) conditions and in malignancy. There is no clinical association that is well-established. Special attention (and critical reflection) is given to the observation that monospecific anti-DFS70 (i.e., in the absence of antibodies that are linked to ANA-associated rheumatic diseases) is rarely found in ANA-associated rheumatic diseases.