Clinical Significances of Antibodies to Ro/SS-A Autoantigens and Its Subtypes in Primary Sjogren’s Syndrome

OBJECTIVE To evaluate the patterns of Ro autoantigen recognition in Korean patients with primary Sjögren's syndrome (SS) and to investigate its clinical significance in SS. METHODS Sera from primary SS (n = 51) and systemic lupus erythematosus (SLE) (n = 132) were tested by double immunodiffusion test and immunoblotting for reactivity with 60 kDa and 52 kDa Ro/SS-A proteins. Clinical manifestations were evaluated on the basis of the presence of anti-Ro/SS-A antibodies and anti-60 kDa/52 kDa proteins. RESULTS The prevalence of anti-Ro/SS-A antibodies in Korean patients with primary SS was 64.7%. In immunoblotting analysis, the incidence of anti-60 kDa without anti-52 kDa was lower in patients with SS(3.0% vs. 11.6%, p > 0.05), whereas anti-52 kDa without anti-60 kDa was more common in SS patients than in SLE patients(42.5% vs. 4.3%, p < 0.001). Patients with anti-Ro/SS-A antibody were significantly associated with the presence of vasculitis, hyperglobulinemia and rheumatoid factor in primary SS (p < 0.05). CONCLUSION The patterns of 52 kDa and 60 kDa Ro autoantigen recognition were quite different in the SLE and primary SS. Anti-52 kDa without anti-60 kDa antibody may be used as a diagnostic marker for primary SS. Although the presence of anti-Ro/SS-A antibody was closely associated with certain clinical features in SS, these clinical manifestations were not correlated with the presence of antibodies against each 52 kDa and 60 kDa proteins. Extended studies with a large population are required to determine the clinical correlation of autoantibodies against each peptides or epitopes of Ro/SS-A proteins.