Assays to determine ENA specificities in the evaluation of any patient suspected of having a systemic connective tissue disease.

 

Samples for Anti-ENA are initially screened using a Fluorescence Enzyme Immunoassay (FEIA) containing all seven antigens. Positive samples are further investigated to identify the individual specificities. the clinical interpretation depends on the ENA specificities that are detected.

 

 

Antibody to Sm antigen is found in a minority of patients with SLE for which it is a very specific marker. the presence of antibody to RNP is found in patients with a variety of systemic connective tissue diseases, including SLE, discoid LE, RA and SS and mixed connective tissue disease.

 

 

Anti-Ro antibody is associated with Primary Sjogrens syndrome and less commonly with SLE. There seems to be close association between the presence of this antibody system and photosensitivity. Two forms of Ro are found, known as Ro60 and Ro52 and antibodies to both may be clinically significant. Both specificities are detected in the assay used. In women of child bearing age Ro antibody is associated with risk of congenital heart block and neonatal lupus.

 

 

Anti-Scl-70 identifies DNA Topoisomerase-1 and is one of several antibodies which give rise to nucleolar staining. This antibody is associated with the more diffuse form of scleroderma/systemic sclerosis, and with impaired pulmonary diffusion.

 

 

Anti-Jo-1 is the most common of a group of myositis-specific antibodies (MSAs) which includes Anti-PL12, Anti-OJ, Anti-Mi-2 and Anti-SRP. These antibodies target aminoacyl-tRNA synthetases (histidyl-in the case of Jo-1). Jo-1 occurs rarely in polymyositis and dermatomyositis, and when present is associated with an increased risk of interstitial lung disease.

 

 

Anti-centromere antibodies (ACAs; often styled solid, anticentromere) are autoantibodies specific to centromere and kinetochore function. They occur in some autoimmune diseases, frequently in limited systemic scleroderma (formerly called CREST syndrome), and occasionally in the diffuse form of scleroderma. They are rare in other rheumatic conditions and in healthy persons.