Summary
Detection of antinuclear antibodies (ANA) by indirect immunofluorescence as say (IIF) is a significant serological criteria in diagnostics of ANA associated rheumatic diseases. A frequent find is dense fine speckled (DFS) fluorescence pattern, associated with anti- DFS70 antibodies. These antibodies are directed against DNA binding transcription coactivator p75, which participates in the mechanisms of cell protection against environmental stress. Anti-DFS70 antibodies can be found in general population, in patients with eye and skin inflammatory diseases, autoimmune thyroiditis and other pathologies. Intriguingly, isolated anti-DFS70 antibodies are rarely found in patients with ANA associated systemic rheumatic diseases, there fore anti-DFS70 has been proposed as a significant biomarker that helps to rule out a diagnosis of such diseases as systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies and mixed connective tissue disease. DFS fluorescence type, associated with anti-DFS70 antibodies, may be difficult to distinguish. Not all samples, in which DFS is observed, are confirmed to be positive for anti-DFS70, when tested with other specific meth ods. The dis crep ancy maybe caused by the variability of ANA fluorescence interpretation among observers, overlapping of ANA patterns or other interacting antibodies. Therefore it is very important to choose the right diagnostic approach, interpret ANA IIF results with caution and use more specific tests, such as immunoblotassay, for confirmation to avoid misinterpretation, misdiagnosis, unnecessary testing and treatment.
