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 Sjogren’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 60kDa and 52kDa Ro/SS-A proteins. Clinical manifestations were evaluated on the basis of the presence of anti-Ro/SS-A antibodies and anti-60 kDa/52kDa 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-60kDa without anti-52kDa was lower in patients with SS(3.0% vs. 11.6%, p>0.05), whereas anti-52kDa without anti-60kDa 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 52kDa and 60kDa Ro autoantigen recognition were quite different in the SLE and primary SS. Anti-52kDa without anti-60kDa 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 52kDa and 60kDa 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.