Detection of DFS70 antibodies : is there an added value for the routine autoimmuno lab?

Background: The recommended method for ANA screening is indirect immunofluorescence (IIF). Nevertheless, up to 30% of healthy individuals are ANA-IIF positive. Recent publications suggested that a considerable portion of these positive patients can be explained by the presence of antibodies targeting the dense fine speckles (DFS70) antigen. Moreover, these antibodies have been found less frequent in systemic autoimmune disease. We aimed to investigate the added value of DFS70 antibody detection (DFS70-Ab) in a routine laboratory setting.Materials & methods: DSF70 antibodies were detected in three cohorts (healthy donors [HD, n=181], systemic lupus erythematosus patients [SLE, n=44], consecutive routine samples on which ANA/anti-ENA was requested [RC, n=222]) using ANA-IIF (HEp-2000, Immunoconcepts) and a chemiluminesence immunoassay (CLIA)(QUANTAFlash, Inova). Specific ANA (anti-ENA) were also detected (EliA Symphony, Thermofisher).Results: Overall, DSF70-Ab were detected in less than 2% (IIF 1.3%, CLIA 1.6%). There was a moderate agreement between both techniques (kappa=0.610). No significant difference in frequencies of DSF70-Ab in our three cohorts could be identified (HD 1.1%, SLE 2.3%, RC 1.8%). These findings were confirmed when only ANA-IIF positive samples (n=250) were taken into account (HD 3.8%, SLE 2.4%, RC 1.9%). Relating the presence of DFS70-Ab with the presence of anti-ENA, we found comparable frequencies within the anti-ENA positive and negative subset (1.8% and 1.6%).Conclusion: Overall frequency of the DFS70-Ab is low; even within the ANA-IIF positives. In addition, we identified these antibodies in combination with other specific ANA. Therefore, little clinical and economical impact is to be expected when implementing this test.

Jaar van publicatie:2014