Antibodies against extractable nuclear antigens (RNP, Sm, SS-A/RO, and SS-B/La)

Autoantibodies against extractable nuclear antigens (ENAs) describe a subgroup of antinuclear antibodies (ANAs) that do not react with chromatin. They are directed against nuclear proteins that were isolated by salt extraction. ENAs are mainly recognized by sera from patients with systemic lupus erythematosus (SLE), mixed connective tissue disease, systemic sclerosis, myositis and Sjögren syndrome. Classical autoantigens are Smith (Sm), ribonucleoproteins (RNPs), Sjögren syndrome A (SS-A/Ro, also known as Robert or Ro), and Sjögren syndrome B (SS-B/La, also known as Lane or La), which are all detectable in sera from patients with SLE. It is recommended that the specific antibody designation is used instead of the global term anti-ENA.