Relationship between autoantibodies and clinical parameters in Sjögren's syndrome

Glandular function as estimated by salivary function scintigraphy and extraglandular manifestations were compared among 174 Sjögren's syndrome (SS) patients according to their anti-Ro/SSA, anti-La/SSB, and anti-U1RNP autoantibody status, to clarify the relationship between these autoantibodies and clinical parameters in SS. These antibodies were detected by RNA-immunoprecipitation. Anti-La/SSB or only anti-Ro/SSA antibody was common in 84 primary SS (P-SS) patients, whereas the frequency of only anti-U1RNP was high in 90 secondary SS (S-SS) patients, especially in those with systemic lupus erythematosus (SLE). Antibody-negativity was common in SS with rheumatoid arthritis and was also found in 33% of P-SS. In P-SS, salivary gland dysfunction and parotid swelling were severe in patients who had serological abnormalities with anti-Ro/SSA and with or without anti-La/SSB. They were mild in antibody-negative patients who had mild extraglandular symptoms and in patients with only anti-U1RNP antibody who had Raynaud's phenomenon, pulmonary fibrosis, and later disease onset. P-SS patients positive for both anti-Ro/SSA and anti-U1RNP had SLE-like features. SS could be classified clinically according to these autoantibodies.