Shedding light on
See all "Shedding light on"
March 2016 The search for antinuclear antibodies (ANA) is a key test in the process of diagnosing systemic, chronic, connective tissue and rheumatic diseases and that search must employ indirect immunofluorescence (IFI) of Hep2 cells which is the reference technique. This is performed in 2 steps: first detection then titration. The result must be based on the concentration (80, 160, etc.) and the appearance (homogeneous, flecked, nucleolar, etc.)
The recently-described DFS70 pattern is characterised by a dense, granular marking of nuclei undergoing interphase and condensed chromosomes in mitosis, which gives them the name “Dense Fine Speckled” or DFS.
It seems that these antibodies are found in greater prevalence in inflammatory situations (atopic dermatitis (71%), granulomatosis panuveitis (69%), interstitial cystitis (5%), etc.) but also in healthy subjects (9%). On the other hand, they seem to be less frequent among patients suffering from connective tissue diseases such as Lupus erythmatosis (2%), Gougerot Sjogren syndrome (2.6%), etc.
Recently, we conducted a study of 12,619 ANA requests to determine the prevalence of this type of fluorescence and its possible link with connective tissue disease. Among the 12,619 serums we studied, 1% (5,820/12,619), had a positive ANA with a significant titer (dilution >= 1/160) and the DFS70 prevalence was 1.5% (83/5,820). It is also interesting to note that almost 90% of the DFS70 patterns had an elevated titer (>=320). Among the 83 serums that displayed this fluorescent pattern, 1 serum (1.2%) also contained anti-double stranded DNA antibodies and this was from a patient who was being monitored for systemic Lupus erythematosus.
Our results, therefore, are consistent with the latest, published data concerning this pattern and tend to show that, in the absence of other, specific antibodies (anti-dsDNA, Sm, SSA, etc.), the ISOLATED DFS70 pattern does not favour connective tissue diagnosis, even if it cannot be 100% excluded. The presence of this pattern, therefore, should be indicated, and might even be included in ANA identification algorithms especially since the 5-year monitoring of healthy subjects, having such antibodies, has shown an absence of any progression towards connective tissue disease.
References
- Le point sur les anticorps anti-DFS70
Coito S. ; 8e colloque Groupe d’Etude en Auto-Immunité 2012 ; p7-11. - Importance of the Dense fine speckled pattern on Hep-2 cells and anti-DFS70 antibodies for the diagnosis of systemic autoimmune diseases
Mahler M et al. ; Autoimmunity Reviews 11 (2012) p 642-645.
