Clinical and laboratory aspects of Ro/SSA-52 autoantibodies

Anti-Ro/SSA antibodies, which were described for the first time in systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS), are the most prevalent extractable nuclear antigen (ENA) specificity identified in laboratories. Two types of anti-Ro/SSA antibodies have been described, anti-SSA-52 kDa (aSSA52) and anti-SSA-60 kDa (aSSA60), each specific to different antigens. Anti-Ro/SSA52 autoantibodies are more frequent than other autoantibodies possibly because of the antigen's accessible and ubiquitous nature. The sites involved and the symptoms associated with these autoantibodies depend on the antigen's structural variability. Isolated congenital complete atrioventricular block (CAVB) shows a close association with maternal anti-Ro/SSA and anti-La/SSB antibodies; the highest relative risks of CAVB are seen in offspring of mothers with antibodies against 52-kDa Ro and 48-kDa La proteins. Anti-Ro/SSA52 antibodies have little impact on adult rheumatic autoimmune diseases or adult cardiac arrhythmias, but the course of autoimmune liver diseases is greatly worsened by their presence, and solid tumours tend to relapse. Their diagnostic role in rheumatic diseases is controversial, although a significant association between isolated anti-Ro/SSA52-kDa positivity and myositis and to a lesser extent with systemic sclerosis (SSc) has been described. However, the majority of the specific diagnosis is mostly based on the simultaneous presence of other autoantibodies that seems diagnostically more relevant.