Identification of the SS-A/Ro intracellular antigen with autoimmune sera

Autoantibodies to SS-A/Ro antigen have been described in the sera of certain patients with Sjögren's syndrome, systemic lupus erythematosus and in neonates with lupus and/or congenital heart block. SS-A/Ro is a trypsin-sensitive intracellular antigen which appears to be associated with another intracellular antigen SS-B/La in tissue extracts. This study describes a simple method of separation of SS-A/Ro and SS-B/La antigenic activity by differential salt elution in polybuffer ion exchange chromatography. The partially purified SS-A/Ro antigen was separated by polyacrylamide gel electrophoresis under non-denaturing conditions and identified by Western blot analysis as a single polypeptide of 61,000 Da. The pI of SS-A/Ro antigen was 4.67. The partially purified SS-A/Ro antigen derived from gel electrophoresis could be adapted to an enzyme linked immunosorbent assay (ELISA) for the detection of antibody.