Anti-Ro/SSA and -La/SSB antibodies in patients with connective tissue diseases.

The frequency of anti-Ro/SSA and anti-La/SSB antibodies in patients from Japan with Sjögren's syndrome, systemic lupus erythematosus (SLE), progressive systemic sclerosis (PSS), polymyositis-dermatomyositis (PM-DM), rheumatoid arthritis (RA) and blood donors is reported. Anti-La/SSB ab was especially detected in patients with severe glandular and extraglandular manifestation and could be found in sera years prior to the confirmation of Sjögren's syndrome. The purified Ro/SSA antigen consisted of 60 k peptide and 16 k RNA while the La/SSB antigen consisted of 41 k and 29 k peptides. Some molecular association seems to exist between the peptides and corresponding IgG anti-Ro/SSA and anti-La/SSB antibodies.