The Sa system: a novel antigen-antibody system specific for rheumatoid arthritis.

Abstract

Anti-Sa antibodies are a novel serological marker highly specific for RA. Since anti-Sa antibodies occur independently of RF, they can be used as an additional diagnostic tool. The molecular nature of the Sa antigen as well as its potential pathogenic role in a significant proportion of patients with chronic articular inflammation of the rheumatoid variety merit further definition.